47
Originally Issued: 10/09 DMS #590159 Page 1 of 47 Revised: 03/01/10 VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

  • Upload
    others

  • View
    6

  • Download
    1

Embed Size (px)

Citation preview

Page 1: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 1 of 47 Revised: 03/01/10

VI.A

BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Page 2: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 2 of 47 Revised: 03/01/10

GUIDE FOR DETERMINATION OF

BARE OVERHEAD TRANSMISSION CONDUCTORS

PJM INTERCONNECTION

January 2010

Heritage MAAC Group

A task force of the Transmission and Substation Subcommittee

PJM Overhead Conductor Ad Hoc Committee:

Baltimore Gas & Electric Lamar Kimp (Chairman) PECO Energy William Magee PECO Energy PECO Energy

Stephen Dasovich Mark Shuck

PPL Electric Utilities Christian Sorensen Public Service Electric & Gas Dmitriy Katsev

Page 3: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 3 of 47 Revised: 03/01/10

Table of Contents

REVISION HISTORY ................................................................................................................................... 5

SCOPE AND PURPOSE .............................................................................................................................. 6

BACKGROUND ......................................................................................................................................... 7

DEFINITIONS ............................................................................................................................................ 8

NON-THERMAL RATING LIMITATIONS ..................................................................................................... 9

WEATHER ................................................................................................................................................. 9

WEATHER MODEL ........................................................................................................................................... 9 DEFINITION OF SUMMER AND WINTER .............................................................................................................. 11

MAXIMUM CONDUCTOR TEMPERATURE ............................................................................................... 11

EFFECTS OF ELEVATED TEMPERATURE OPERATION ............................................................................... 12

LOSS OF STRENGTH DUE TO ANNEALING ............................................................................................................ 12 PREDICTING LOSS OF STRENGTH OF CONDUCTORS DUE TO ANNEALING.................................................................... 13 CREEP EFFECTS OF ELEVATED TEMPERATURE OPERATION ..................................................................................... 14 ALUMINUM WIRE COMPRESSION OF ACSR CONDUCTORS OPERATING AT ELEVATED TEMPERATURES ........................... 14

FITTINGS/ACCESSORIES/HARDWARE ..................................................................................................... 16

RISK ....................................................................................................................................................... 16

FIGURE 8-1 ................................................................................................................................................. 17 EMERGENCY RATINGS .................................................................................................................................... 18 LOAD DUMP RATINGS .................................................................................................................................... 18

PARAMETERS FOR CALCULATIONS ......................................................................................................... 19

NORMAL CONDITIONS ................................................................................................................................... 19 EMERGENCY & LOAD DUMP CONDITIONS .......................................................................................................... 20 DISCUSSION OF ASSUMPTIONS FOR AMPACITY CALCULATIONS USING THE METHOD OF IEEE STD. 738-2006 ............... 21

IEEE STANDARD 738-2006 FOR CALCULATING THE CURRENT-TEMPERATURE OF BARE OVERHEAD CONDUCTORS ........................................................................................................................................ 22

DESCRIPTION OF IEEE 738 ............................................................................................................................. 22

INSTRUCTIONS FOR USING THE PJM OHT CONDUCTOR RATINGS SPREADSHEET ................................... 23

COMPARISON OF THE PJM OHT CONDUCTOR RATING SPREADSHEET ................................................... 25

APPENDIX 1 FREQUENCY DISTRIBUTION OF WIND AND AMBIENT TEMPERATURE CONDITIONS ........... 27

TABLE 12-1 – SUMMER .............................................................................................................................. 27 TABLE 12-2 – WINTER ................................................................................................................................. 28 FIGURE 12-3................................................................................................................................................ 29

Page 4: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 4 of 47 Revised: 03/01/10

APPENDIX 2 EXAMPLE OF LOSS OF STRENGTH CALCULATIONS .............................................................. 30

EXAMPLE OF LOSS OF STRENGTH CALCULATION FOR 1590 KCMIL 45/7 ACSR (LAPWING) ......................................... 30 STEP 1 CALCULATE INITIAL STRENGTH OF THE CONDUCTOR AND ALUMINUM AND STEEL COMPONENTS ................. 31 STEP 2 DETERMINE REMAINING STRENGTH (RS) OF ALUMINUM STRANDS ....................................................... 31 STEP 3 DETERMINE THE REMAINING STRENGTH OF THE CONDUCTOR .............................................................. 31 STEP 4 DETERMINE LOSS OF STRENGTH OF THE CONDUCTOR ......................................................................... 31

STEADY STATE THERMAL RATINGS......................................................................................................... 32

REFERENCES ........................................................................................................................................... 47

Page 5: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 5 of 47 Revised: 03/01/10

REVISION HISTORY August 2000: Rev. 0 – Original Document March 2010: Rev. 1 – General revision and document standardization and clarification of emergency and load dump ratings, revision of associated equations, and upgrade of associated Excel spreadsheet.

Page 6: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 6 of 47 Revised: 03/01/10

SCOPE AND PURPOSE In 2008 the Heritage MAAC group requested that the PJM Transmission and Substation Subcommittee provide an update to the Bare Overhead Transmission Conductor Ratings guide. An Ad Hoc Committee was formed and charged with addressing the following issues: The PJM Overhead Transmission (OHT) Ratings spreadsheet was expanded to include conductors rated 100 kV and above, which are considered part of the Bulk Electric System (BES) and are subject to the guidelines set forth in the PJM Operating Manuals. High Temperature Low Sag (HTLS) conductors such as aluminum conductor composite core (ACCC) and aluminum conductor composite reinforced (ACCR) were also added to the spreadsheet. Transmission owners also have the ability to add additional conductors to the spreadsheet as needed. The OHT Ratings spreadsheet was updated to include a method for calculating the conductor load dump ratings. All ratings in the spreadsheet are given in amperes and diligence should be used when converting to MVA when using nominal voltage (e.g. phase imbalances, operating voltage). The output of the OHT Ratings spreadsheet was modified to match that in the Outdoor Substation Conductor Ratings. Due to the number of conductors now included in the spreadsheet and the addition of the load dump rating it was decided that this updated document will not include a printout of all the EXCEL outputs in Appendix 6. Instead only a sample output will be included. Instructions for using the latest version of the spreadsheet have also been added. This document addresses the issues associated with the rating of bare overhead conductors. Often these ratings are the most limiting ratings on a circuit or feeder, but not always. The ratings provided in this document must not be confused with circuit ratings; they are only one component in the analysis to determine the circuit rating. This document and the ratings spreadsheet are voluntary guidelines and may be applied at the transmission owner’s discretion. The committee was also charged with defining the transition point between transmission and substation ratings jurisdictions. Working in conjunction with the Outdoor Substations Conductor Ratings Ad Hoc Committee the following consensus was established: “Regardless of the installation method, the point of demarcation is the connection of the insulator string to the overhead conductor at the dead end structure. The dead end referenced should be the structure that transitions the line to any type of substation equipment. Underground cable transition is at the end of the pot head.” However, the intent of the point of demarcation is to prevent a high temperature overhead conductor from overheating temperature sensitive substation equipment. Conductor drops from a take-off tower may be rated as line conductor if attached to non-temperature sensitive substation components.

Page 7: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 7 of 47 Revised: 03/01/10

BACKGROUND This guide outlines a methodology for determining thermal ratings of overhead transmission conductors. This document resulted from the effort to update an earlier PJM guide: Bare Overhead Transmission Conductor (November, 2000). The bulk of the work of the Overhead Conductor Ad-Hoc Committee focused on the following:

Defining the transition between transmission and substation rating jurisdiction.

Inclusion of high temperature conductors (ACSS, ACCR, ACCC).

Describing the impact of high temperature conductor on interface with lower temperature conductor.

Addressing the thermal effect of multiple conductors in close proximity.

Defining the procedure for determining load dump ratings.

Revising the existing spreadsheet for calculating overhead ratings. A major accomplishment was the update of the existing Microsoft Excel spreadsheet for determining overhead ratings. The spreadsheet was revised to include a full range of modern high-temperature conductors. Additionally, functionality for determining load dump ratings was developed and included in the spreadsheet. The spreadsheet was thoroughly tested to ensure comparable performance to industry-standard programs for determining overhead conductor ratings. A how-to guide on the use of the new spreadsheet is provided in this document. A comparison table showing the output values of the spreadsheet and commercial software is also provided. The assumptions regarding climatic and conductor conditions remain unchanged from the previous revision of the document. An engineer already familiar with overhead ratings and the previous revision of this document will not notice any significant changes in the core algorithm for determining the overhead ratings. The entire document, however, is more-user friendly compared to the earlier edition as much of the vague or subtle verbiage has been revised or eliminated. The year 2000 manual is included as an appendix of this document. All versions of this document dated prior to 2000 are included in the appendices as well. It is assumed that power levels will be maintained and managed within the requirements of PJM Manual 3, Section 2, “Thermal Operating Guidelines”. PJM operating philosophy strives to restore loads to below the Normal Rating in four hours or less. The intent of this guide is that equipment loading will not be above the Normal Rating for greater than four hours. It is understood that under a single event restoration, cumulative time of loading, in excess of the Normal Rating, beyond four hours may occur. Operating in excess of four hours above the Normal Rating for a single event restoration should be evaluated by the equipment owner.

Page 8: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 8 of 47 Revised: 03/01/10

DEFINITIONS Following are definitions of terms used in this report for use in determining PJM switch ratings: Continuous Duty A duty that demands operation at a substantially constant load for an indefinitely long time. Short Time Duty A duty that demands operation at a substantially constant load for a short and definitely specified time. Normal Conditions All equipment in normal configuration, normal ambient weather conditions. Normal Rating The maximum permissible constant load at normal conditions, at the maximum allowable conductor temperature for that conductor. Emergency Conditions Equipment has been operating at Normal Rating. The equipment is then exposed to an out of configuration condition and emergency ambient weather conditions. Emergency Rating The maximum permissible steady-state load at emergency conditions, at the maximum allowable conductor temperature for a period not to exceed 24 hours. Load Dump Rating The maximum permissible load at emergency conditions, at the maximum allowable conductor temperature for a period of 15 minutes as determined by the transient method. Weather Conditions Ambient temperature, solar and sky radiated heat flux, wind speed, wind direction, and elevation above sea level. Max. Allowable Conductor Temp. The maximum temperature limit that is selected in order to minimize loss of strength, conductor sag, line losses, or a combination of the above. Time Risk The time during which the conductor is vulnerable to operation at temperatures greater than the design temperature. Temperature Risk The maximum increase in conductor temperature above design temperature which can be experienced if the conductor carries its rated current simultaneously with an occurrence of the most severe set of ambient conditions.

Page 9: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 9 of 47 Revised: 03/01/10

Non-thermal Rating Limitations Situations may arise where limitations other than the thermal rating of the conductor will limit the maximum rating of the circuit. Other electrical devices such as wave traps, switches, transformers, disconnects, breakers, and relays. Legal or contractual limitations will sometimes restrict operating practices to limit magnetic fields due to field concerns. On shared rights-of-way, other entities (railroads, for example) may impose maximum current limits to minimize inductive interference. Interference issues should always be addressed when determining loading on a line. Potential interference or inductive coupling may cause hazards to other utilities or other lines within the right of way. At times system conditions require a limit on the maximum amount of current flowing through a line. This may require the line being taken out of service or devices added which limit the amount of current carried through the line.

Weather Ambient weather conditions have a major effect on the calculation of a conductor’s thermal rating. Wind speed is the most widely varying parameter and the most important determinant of ratings. Careful selection of weather parameters for thermal rating calculations is as important as the selection of method of calculation itself and requires considerable engineering judgment. Since the publication of “Ambient Adjusted Thermal Ratings For Bare Overhead Conductors” in May 1980 and its acceptance by the PJM companies, wind speed and ambient temperature became the major determining factor related to weather for the calculation of steady state thermal ratings of conductors for daily operation. In the original PJM work, the weather data included 10 years of data from Pittsburgh (1/1/49 –12/31/58) and 16 years of data from Washington D.C. National Airport (1/1/49 – 12/31/64). These were added together and used as being the total composite hourly record of wind data for 26 years. Any differences between the two different weather data sets were obscured by combining the data.

Weather Model

Under actual operating conditions, conductors experience fluctuations in load and weather conditions. This complex relationship is not adequately represented by a set of fixed parameters. A probabilistic model, however, can utilize actual weather data and load cycle characteristics to represent the conductor’s operating history. This model produces a time distribution of conductor temperature which can be used to calculate the loss of strength that a conductor would experience. This modeling technique allows conductors to be rated to meet the constraints of maximum allowable temperature and/or allowable loss of strength.

Page 10: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 10 of 47 Revised: 03/01/10

A weather model is the heart of the simulation. Weather conditions, especially wind, have a marked effect on conductor temperatures. For the PJM weather model, detailed weather data were gathered from several locations representative of the PJM area. Two of the locations had hourly recordings of weather data on magnetic tape for periods exceeding ten years. These hourly recordings were summarized in frequency distribution tables, called “wind roses” which tabulate the statistical distribution of wind speed for each five-degree range of ambient temperature. Wind roses were prepared from day and night data in order to allow the exclusion of solar heating during the night hours. The hour-by-hour weather data used to make the wind roses was examined to determine whether prolonged periods of simultaneous still air and high temperature exist. No such prolonged periods were found; three successive hours at temperatures in excess of 25°C was the longest period recorded. However, this examination of the wind roses for each of the locations revealed a higher than expected occurrence of recorded still air. The same data indicated few occurrences of one and two knot winds. The Environmental Sciences Services Administration (ESSA) was consulted for an explanation, and the wind roses were studied by their Science Advisory Group at the National Weather Records Center (NWRC.) The NWRC advised that due to bearing friction and inertia in the standard cup anemometers used by ESSA, many of these instruments will not begin to record until the wind speed exceeded two or three knots. A paper, “Bias Introduced by Anemometer Starting Speeds in Climatological Wind Rose Summaries” discussed this problem and concluded that there is indeed a strong measurement bias but offered no solution to the problem of how to overcome this bias. The NWRC suggested that the calm hours be apportioned over the zero, one, and two knot ranges. This reapportionment was made and the resulting adjusted weather data from several locations in PJM territory were combined into a single matrix. Computations using weather data from each individual location yielded results which were essentially identical to those computations made using the combined data. Based on this computation, it was decided that a single weather model can be used. In order to complete the simulation of the operating experience of the conductor, it is necessary to determine the shape of the load cycle, which the conductors will experience. A representative load cycle was prepared from studies of actual PJM line loadings. A step function approximation was made to represent this cycle. The 2000 Task Force believed that if it had to purchase new weather data, the weather data would lead to the same conclusions, based on anecdotal information. Glenn Davidson, who did much of the original work as the Chair of the 1973 PJM Conductor Rating Task Force, and who attended the May 1999 meeting of this Task Force, also shared this opinion. The 2009 Task Force accepted the assumptions made in the original PJM Conductor Rating calculations to remain valid and applicable.

Page 11: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 11 of 47 Revised: 03/01/10

Definition of Summer and Winter

For planning purposes summer is defined as the nine month period extending from March through November and having an ambient temperature of 35°C. Winter is defined as the three month period extending from December through February and having an ambient temperature of 10°C. These values are very conservative as the winter wind chills are less than or equal to 10°C over 88% of the time. The actual summer temperatures are less than or equal to 35°C 99% of the time. These are the values used by planners to determine the need to add transmission capacity. The system operators have tables of ambient adjusted ratings with values between -15° and 40° in 5 degree increments to determine ampacities in effect at any given temperature.

Maximum Conductor Temperature Each Transmission Owner determines the maximum operating temperature for a conductor by consideration of several factors. Those factors include:

The requirement to maintain clearance from the aerial line conductors to the ground and other features.

The capability of the specific conductor type to operate at a given temperature without an unacceptable reduction in strength or corrosion protection.

The compatibility of the conductor temperature with fittings and other line hardware and insulation.

The National Electrical Safety Code (NESC) sets the minimum permissible clearance to ground and other features for aerial transmission lines. In some cases the practice of Transmission Owners is to design and operate lines with a specified margin of clearance in excess of the NESC minimums. The selected maximum operating temperature of line conductors shall be consistent with design and operating assumptions for maximum line sag and the design clearance to ground and other features and obstructions. The minimum strength required for a conductor is set by the NESC and by specific requirements of the individual Transmission Owners. The strength requirement is a factored value of the design tension of the line. Application of high temperature to stranded conductors can reduce the strength of the conductor and could impact compliance with NESC and Transmission Owner requirements. For conductors such as ACSR, ACAR, and AAC that use hardened aluminum wires (1350-H19) or aluminum-alloy wires (6201-T81), the application of temperatures in excess of 100°C can result in annealing of the wires and loss of strength. The selection of the maximum operating temperature for these conductor types requires an assessment of the expected loss of strength over the expected life of the line compared to the required strength set by NESC or owner requirements. Section 6 examines the implications of elevated temperature operation and discusses risk assessment. ACSS conductors use annealed aluminum wires (1350-0). The rated strength of ACSS conductors is primarily the strength of the steel core plus the small strength contribution of the annealed

Page 12: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 12 of 47 Revised: 03/01/10

aluminum wires. Since the aluminum wires are already annealed, application of high temperature will not further reduce the strength of the wires or the overall conductor. In the case of ACSS conductors, the maximum temperature is limited by the temperature susceptibility of the protective coating of the steel core wires and temperature capability of dead-ends, spices, and other fittings. Typically the steel core wires of ACSS conductors use a zinc - 5% aluminum-mischmetal alloy coating (Galfan) instead of conventional galvanizing to permit operation up to 250°C. Conductor types with non-metallic cores (ACCC and ACCR, for example) use a composite material as the primary strength member of the conductor replacing the typical steel core wires. These conductor types use aluminum wires as the conductive component of the construction. The aluminum wires may be hardened, annealed, or may be a heat-resistant aluminum alloy (aluminum-zirconium). The maximum operating temperature of non-metallic core conductors should be determined by the properties of the specific conductor materials, both the core and the aluminum, as set by the conductor manufacturer.

Effects of Elevated Temperature Operation Operation of bare overhead conductors at elevated temperatures can have detrimental effects on the strength and sag characteristics of the conductor. Those effects can occur when operating temperatures exceed 100°C.

Loss of Strength due to Annealing

Annealing is the metallurgical process where applied temperature softens hardened metal resulting in loss of strength. As applied to bare, overhead conductors, annealing can degrade the strength of aluminum 1350-H19 wires: the wires used in ACSR and AAC conductors. About 70% of the strength of 1350-H19 aluminum is a result of hardening. Annealing of aluminum 1350-H19 begins at 93°C and is a function of both the magnitude of the temperature and the duration of the application. At lower temperatures (below 100°C), the effect is negligible. At higher temperatures (above 200°C), the effect can be significant and occur quickly.

The rated strength of a stranded conductor is the sum of the strengths of the individual wires, factored to account for stranding. An all-aluminum conductor (AAC) derives all its strength from the aluminum wires. In the case of AAC, the loss of strength of the conductor due to annealing is directly proportional to the degradation of the aluminum. Similarly, aluminum conductor, alloy reinforced conductors (ACAR) use both 1350-H19 wires and aluminum-alloy 6201-T81 wires. Both are subject to annealing, and the loss of strength for ACAR is directly proportional to the degradation of the aluminum and aluminum-alloy. For both AAC and ACAR conductors, the maximum allowable conductor temperature should not significantly exceed the annealing temperature of aluminum. Conductor operating temperatures of up to 100°C have a negligible risk of annealing the aluminum wires and are considered acceptable for AAC and ACAR conductors.

Page 13: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 13 of 47 Revised: 03/01/10

Aluminum conductor, steel reinforced conductors (ACSR) use a core of steel wires overlaid by one or more layers of aluminum 1350-H19 wires. The steel wires will not anneal at temperatures used for ACSR operation. For ACSR, the loss of strength of the conductor is a function of the loss of strength of the aluminum wire component of the conductor compared to the rated strength of both the aluminum and steel wires. A typical ACSR conductor derives about half it its strength from the steel wires and half from the aluminum wires. ACSR Drake (795kcmil 26/7), for example, derives 44% of its strength from the aluminum wires and 56% from the steel wires. If elevated temperature operation reduces the strength of the aluminum wires by 20%, the overall strength of the conductor will be reduced by 9%. Since the degradation of the aluminum wires only partially impacts the overall conductor strength, conductor temperature in excess of the annealing temperature of aluminum can be applied to ACSR such that the maximum loss of overall strength of the conductor is limited to 10%.

Some aerial conductor types are designed to eliminate or reduce the effect of annealing on conductor strength. Aluminum conductor, steel supported conductors (ACSS) use fully annealed aluminum 1350-0 wires over a core of steel wires. The strength of ACSS conductor is virtually all from the steel core. Since the aluminum wires are already annealed, elevated temperature operation has no effect on the strength of the aluminum wires or the conductor. Accordingly, the maximum temperature of ACSS conductors is set by the thermal capability of connectors and by the heat resistance of the protective coating on the steel wires. New conductor constructions use composite core materials. These conductors also use aluminum wires surrounding the composite core that are either annealed or are heat resistant during high-temperature operation. The specific effects of temperature on these types of conductors should be obtained from the manufacturer.

Predicting Loss of Strength of Conductors due to Annealing Calculating the projected loss of strength of ACSR and other conductors subject to annealing at elevated temperatures requires a complex analysis of the metallurgical aspects of the wires and the probability of weather and electrical power flow conditions. The operating temperature of the conductor is a function of several inter-related parameters that include wind and the current being carried. The line rating and the associated conductor operating temperature are based on electric current and weather parameters that are conservative to ensure safe and reliable system operation. However, actual wind speeds will generally be higher than that assumed for ratings, and actual electrical load will generally be less than the full line rating. Thus the conductor operating temperature of most lines will almost always be lower than the maximum temperature used for rating the line. Most lines will experience design-case conditions and operating temperatures for a few hours a year, at most. The loss of strength due to annealing of the aluminum wires is a temperature and time dependant phenomenon. The key to determining the probable loss of strength over the expected life of the conductor is to predict the amount of time the conductor will experience temperatures that will result in annealing. That time prediction requires an assessment of the projected load patterns of the line and the predicted wind patterns.

Page 14: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 14 of 47 Revised: 03/01/10

Once a matrix of load and wind is established, a tabulation of conductor temperatures and expected durations can be developed. From that tabulation the cumulative annealing effect can be calculated and the projected remaining strength of the conductor can be determined. Appendix 2 provides guidance to the calculation of predicted loss of strength of conductors subject to annealing. The information and sample calculation in Appendix 2 is highly simplified and is not appropriate for all conditions. For specific information regarding the effect of high temperature operation on bare overhead conductors see: IEEE-1283-2004; IEEE Guide for Determining the Effects of High-Temperature Operation on Conductors, Connectors, and Accessories; Institute of Electrical and Electronics Engineers

Creep Effects of Elevated Temperature Operation

Operation of conductors at high temperature can increase the creep effect of conductors affecting sag. Creep is the non-elastic relaxation of material over time. The effect of creep on aerial conductors is to have line sag increase over years even in the absence of extreme loading events. Aluminum 1350-H19 wires are subject to creep. Lines designed for elevated temperature operation should have sags and tensions derived with creep as a consideration in order to ensure adequate clearance to ground and other obstructions over the long term.

Aluminum Wire Compression of ACSR Conductors Operating at Elevated Temperatures

Research has indicated that ACSR conductors exposed to high temperature operation can sag more than the values predicted by conventional sag-tension programs. This is the result of the aluminum wires going into compression at high temperatures. The coefficient of thermal expansion of aluminum wire is higher than that of steel wire. Subject to elevated temperatures, the aluminum wires of ACSR will attempt to lengthen more than the steel wires. Since the aluminum wires are held tightly to the steel wires by the stranding, the aluminum wires will be forced to the same elongation as the steel wires. The result is that the aluminum wires at high temperature will either buckle outward in an effect called “bird caging”, or the wires will go into a compressive stress state. If the aluminum wires go into compression, they will impose an equal tensile force on the steel wires. That additional tension will clause the steel wires to elongate more than predicted by conventional methods and will result in greater line sag. The greater sag could result in unexpected clearance issues. The actual, real world impact of aluminum wire compression is not clear. Typically it is not an issue for operating temperatures up to 120°C. Even at higher temperature it may range from nothing, if the aluminum wires are assumed to birdcage and relieve compression, to 100% of theoretical aluminum wire compression. For a typical line

Page 15: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 15 of 47 Revised: 03/01/10

using ACSR Drake conductor with 900-foot spans and operating at 140°C, the additional sag resulting from the assumption of aluminum wire compression is about 2 feet. Most modern sag-tension calculation programs permit analysis assuming aluminum wire compression as an option. The decision to assume compression of the aluminum wires of ACSR should be governed by operating experience.

Figure 8-1

Conductor Size

100 110 120 125 130 140 150 160 170 180

2493 kcm 54/37 ACAR 2.83 3.76 5.77 7.56 9.72

2312 kcm 76/19 ACSR 1.58 2.65 4.25 5.08 6.18 8.54

2300 kcm 84/19 ACSR 0.00 0.68 1.95 2.76 3.55 5.57 7.77

2167 kcm 72/7 ACSR 1.40 2.45 4.17 4.98 5.91 8.30

2156 kcm 84/19 ACSR 0.00 0.18 1.49 2.26 2.96 4.90 7.11 9.93

1780 kcm 84/19 ACSR 0.00 0.71 1.95 2.79 3.53 5.63 7.79

1590 kcm 54/19 ACSR 0.00 0.00 0.00 0.20 0.80 2.30 4.20 6.40 8.40

1590 kcm 45/7 ACSR 0.00 0.86 2.15 2.95 3.80 5.71 8.03

1272 kcm 54/19 ACSR 0.00 0.00 0.00 0.18 0.86 2.43 4.19 6.24 8.30 10.47

1272 kcm 45/7 ACSR 0.00 0.85 2.25 2.94 3.87 6.09 8.17

1033.5 kcm 54/7 ACSR 0.00 0.00 0.00 0.27 1.00 2.52 4.24 6.33 8.31 10.34

1033.5 kcm 45/7 ACSR 0.00 0.88 2.25 3.08 3.93 5.88 8.28

795 kcm 30/19 ACSR 0.00 0.00 0.00 0.00 0.00 0.00 0.62 1.95 3.46 4.92

795 kcm 26/7 ACSR 0.00 0.00 0.00 0.00 0.00 1.20 2.80 4.40 6.20 8.00

634.9 kcm 12/7 ACAR 3.09 4.19 6.23 7.77 9.98

556.5 kcm 24/7 ACSR 0.00 0.00 0.00 0.42 1.06 2.80 4.20 5.88 7.85 9.74

477 kcm 26/7 ACSR 0.00 0.00 0.00 0.00 0.26 1.68 2.94 4.34 6.07 7.92

336 kcm 26/7 ACSR 0.00 0.00 0.00 0.04 0.58 1.92 2.94 4.37 5.98 7.82

336.4 kcm 18/1 ACSR 1.30 2.56 4.78 5.83 6.98 9.03

300 kcm 26/7 ACSR 0.00 0.00 0.00 0.08 0.74 2.02 2.94 4.32 6.08 7.87

300 kcm 19 str AAC 5.43 7.61 10.28

Assumptions: Conductor operates for 35 years to PJM Load Cycle as shown in Appendix #3, Pg A-7, Figure #3

Conductor emissivity =0.7 and apsorptivity =0.9

Winter Rating Conditions: Normal 20oC, no wind / Emerg 10

oC, 1 knot

Summer Rating Conditions: Normal 35oC, no wind / Emerg 20

oC, 1 knot

Maximum Design Conductor Operating Temperature (oC)

Conductor Loss of Strength in % Based on PJM Weather Model

From the 1973 PJM Report

Page 16: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 16 of 47 Revised: 03/01/10

Fittings/Accessories/Hardware Fittings used on a transmission line serve both electrical and mechanical functions. Conductor fitting must be compatible with the conductor type and the selected maximum operating conductor temperature. Electrically, the fittings must establish and maintain low contact resistance, must not generate radio noise at the design voltage and must not exceed the temperature of the conductor. Mechanically, full tension fittings must be capable of holding 95% of the conductor’s rated strength and non-tension fittings should be capable of holding at least 10% of the rated strength of the conductor. Compression fittings, properly installed with the manufacturer’s recommended practice and joint compound, are capable of transferring the maximum current. Fittings used with conductors operating at high temperature, typically over 200°C, should be designed specifically for high temperature operation. Lines using conventional fittings should not be operated at temperatures in excess of the fitting capability regardless of the conductor type. If the rating of an existing line is to be increased by increasing the maximum operating temperature, an assessment should be made to ensure the compatibility of the existing fittings with the proposed operation. There is a PJM study that addresses this concern.

Risk As discussed previously, overhead conductor ratings are affected by many factors, but the most significant of these many parameters is wind speed. But unlike many of the other factors such as absorptivity, ambient temperature, conductor resistance, etc., wind speed is truly variable in magnitude and direction. In the early PJM work, summarized by the “Determination of Thermal Ratings for Bare Overhead Conductor, 1973”, weather data was collected from Washington DC over a period of 16 years, and from Pittsburgh over a 10 year period. These data were pooled to represent a 26-year span for an average PJM condition. The weather data were summarized on pages A18 and A19 in the 1973 Report in a table format for the frequency distribution of wind and ambient temperature conditions. The tables are reprinted in this report as Appendix 1, Tables 12-1 and 12-2. In these tables each row list the probability of occurrence of a given wind speed at a specified ambient temperature. Alternately, each row gives the probability of occurrence of different ambient temperatures given the particular wind speed.

When rating transmission conductors, the choice of wind speed used is important due to the significant effect on the rating. While a higher wind speed is desired for the higher rating, there is a cost. What happens if the wind speed that actually occurs along the transmission line is less than the assumed value? As the original PJM work showed, the wind speed is characterized by a distribution of wind speeds with higher and lower values. A wind speed lower than assumed would drive a higher conductor temperature than assumed. For example, if a rating were based

upon 100C with 2 feet/sec. of wind and a lesser wind were to occur it would cause an increase in conductor temperature above 100°C. This risk of increase in conductor temperature is called temperature risk.

Page 17: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 17 of 47 Revised: 03/01/10

The duration of these lower wind speeds is also of concern. The acceptability of a temperature

risk changes with the duration of that risk. For example, while a temperature overrun of 25C would not be of major concern for 5 minutes, it would be more problematic if it were for 6 hours during mid-day. The risk due to the duration of an over temperature condition is called time risk. Figure 8-1 shown below depicts these risks. On the horizontal axis are listed wind speeds, and on the vertical axis are the probabilities of wind speeds at or less than the listed values. For example wind speeds of 1 knot (1.69 ft./sec.) or less are likely 1% of the time, and this increases to 10% for 4 knots (6.76 ft./sec.) of wind.

Figure 8-1

Page 18: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 18 of 47 Revised: 03/01/10

This chart also details the temperature risk as the labels next to each data point. For example, with 3 knots of wind the temperature of an overhead transmission conductor would increase in temperature by up to 104oC at different combinations of ambient temperatures and lesser wind

speeds. For this 3-knot condition, the temperature risk would be 104C with the time risk equivalent to 5% of the time, or 438 hours per year. The original PJM CRTF evaluated these risks and developed a reasonable approach to manage these risks. Normal ratings were to be based upon 0 knots of wind. This is a conservative approach since there is no risk that a lesser wind speed would occur. Therefore there is neither temperature nor time risk. The original PJM work determined that a conductor would operate under emergency conditions for 350 hours over its 35 year life. As a result, this approach was chosen knowing that the normal rating applies 99.9% of the time. However, the original CRTF did acknowledge the need for an increased rating for an emergency condition. In an effort to provide this capability, an emergency rating based upon 1 knot of wind was selected. This condition resulted in a 1% risk of a lesser wind speed occurring (time risk) and this was believed to be acceptable for an emergency condition. Additionally, the temperature risk was calculated

to be approximately 30C for the commonly used PJM 230 kV Lapwing transmission conductor. While this is fairly significant, the resulting increase in conductor sag was calculated to be approximately 2 feet for a standard 230 kV span length and tension. This increase in sag was up to about 3 feet safety factor that all PJM companies added to the required ground clearance requirements. Therefore the temperature risk was actually of no effect since NESC clearances were not violated. The recommendation of the 1999 CRTF and the 2009 Ad Hoc group regarding wind and weather assumptions for normal and emergency ratings is given in Section 9.0.

Emergency Ratings Emergency ratings are provided for abnormal out of configuration system conditions. These ratings allow the system operators to take advantage of ambient wind speed to ride through short time duties without endangering the public. Since a 1% risk is accepted for emergency ratings, these ratings are limited to abnormal configurations and a very specific duration. The longer the short time duration, the more risk is assumed. Emergency Rating periods are not to exceed 24 hours. Due to the thermal time constant of electrical conductors, all emergency ratings longer than 15 minutes are essentially the same. The only increase available is by assuming more risk.

Load Dump Ratings Load dump ratings are calculated on a similar basis as Emergency Ratings except that the duration of the Load Dump period shall not exceed 15-minutes. The same conditions as stated in Section 8.1 for Emergency Ratings apply; however, initial conditions are based upon parameters set forth in section 9.

Page 19: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 19 of 47 Revised: 03/01/10

Parameters for Calculations This section of the report summarizes the assumed program parameters for normal and emergency conditions.

Normal Conditions Normal Operating Conditions assume that all equipment and conductors are available and in normal operating configuration. The normal weather conditions, as listed below, are assumed to exist during normal operating conditions. During normal weather conditions it is assumed that the conductor under consideration can operate at continuous duty. The normal ratings are based upon normal weather conditions and have insignificant risk of exceeding the conductor’s design temperature since they incorporate a zero wind speed.

Typical Normal Conditions-Summer

Ambient Temperature: 35C

Wind Speed: 0 feet per second Wind Direction: 90o to conductor Solar/ Sky: Day -Industrial Elevation: 200 ft above sea level

Max. Allowable conductor temp.: 100°-250°C(material dependent) Latitude: 40 North Sun Time: 14:00 Emissivity: 0.7 Absorptivity: 0.9

Typical Normal Conditions-Winter:

Ambient Temperature: 10C

Wind Speed: 0 feet per second

Wind Direction: 90o to conductor

Solar/ Sky: Day - Industrial

Elevation: 200 ft above sea level

Max. Allowable conductor temp.: 100-250°C(material dependent)

Latitude: 40 North

Sun Time: 14:00

Emissivity: 0.7

Absorptivity: 0.9

Note: The ambient temperatures above are used for planning and represent two of the ambient temperature sets used for operations.

Page 20: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 20 of 47 Revised: 03/01/10

Emergency & Load Dump Conditions Emergency Operating Conditions require that the conductor under consideration operate for a short time above its normal rating. The weather conditions for conductor rating during emergency conditions are specified below. Therefore, this short time emergency rating is limited to no more than 24 hours per occurrence and 15 minutes for load dump ratings. These ratings are based upon a 1 % risk of exceeding the conductor’s design temperature.

Typical Emergency Conditions-Summer:

Ambient Temperature: 35C

Wind Speed: 1.5 Kt. (2.533 ft/sec.) Wind Direction: 90o to conductor Solar/ Sky Radiated Heat Flux: Day - Industrial Elevation: 200 ft above sea level Max. Allowable conductor temp.: 100-250°C(material dependent) Latitude: 40 North

Sun Time: 14:00 Emissivity: 0.7 Absorptivity: 0.7

Typical Emergency Conditions-Winter:

Ambient Temperature: 10C

Wind Speed: 1.5 Kt. (2.533 ft/sec. ) Wind Direction: 90o to conductor

Solar/ Sky Radiated Heat Flux: Day - Industrial Elevation: 200 ft above sea level

Max. Allowable conductor temp.: 100-250°C(material dependent)

Latitude: 40 North

Sun Time: 14:00

Emissivity: 0.7

Absorptivity: 0.9

Note: The ambient temperatures above are used for planning and represent two of the ambient temperature sets used for operations.

Page 21: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 21 of 47 Revised: 03/01/10

Discussion of Assumptions for Ampacity Calculations Using the Method of IEEE Std. 738-2006 Day and Night Ratings Daylight hours are, for operating purposes, between sunrise and sunset. Night ratings should be used during all other periods.

Atmosphere The task force evaluated the environmental conditions in the PJM service area and selected the “industrial” atmosphere.

Sun Time The sun times available for use range between 10:00 am and 2:00 pm in hourly steps. The task force chose 2:00 p.m. because that time is nearest to the typical peak ambient temperature.

Latitude The task force chose 40 degrees north as this latitude approximately divides the PJM service territory in half.

Conductor Direction The task force studied a geographic map of the PJM service territory and determined that it became apparent that most lines are primarily oriented east-west. Therefore this direction was chosen as the input for the program.

Wind Direction

The task force chose the wind angle of 90 degrees to the conductor, which is consistent with earlier PJM work. It also results in maximum cooling for any given wind speed. Conductor Elevation

The task force discussed the various terrain and elevations within their respective areas and agreed to a conductor elevation of 200 feet above sea level as a good average value. Conductor Resistance

Conductor AC resistance values are calculated by each manufacturer and these values may vary for the same conductor type and size. This can cause a variance in the rating calculation. ASTM committee B-1 is considering development of a standardize methodology for calculating AC resistance values. Until ASTM issues their methodology document it is recommended that each utility consistently use ac resistance values from one source. The AC resistance values used in the PJM rating spreadsheet are listed in the spreadsheet. Each utility is responsible to verify that the ac resistance values in the spreadsheet meet their standard.

Page 22: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 22 of 47 Revised: 03/01/10

Emissivity/Absorptivity The task force sees no reason to change the values of emissivity and absorptivity adopted in previous reports as these values are the result of original work. To our knowledge, this work has never been repeated. The values used are:

emissivity = 0.7, absorptivity = 0.9 for daytime and 0.0 for nighttime.

For additional discussion, see Appendix C of the 1973 PJM Report. Conductor Temperature

Maximum conductor operating temperature should be between 100C and 250C.

IEEE Standard 738-2006 For Calculating the Current-Temperature of Bare

Overhead Conductors The 2009 PJM Ad-Hoc group was tasked with updating the existing “PJM OHT Conductor Rating” spreadsheet by adding Load Dump Rating calculations and updating the format to match the format of the “Outdoor Substation Conductor Ratings” spreadsheet. The new spreadsheet contains a new user friendly data input page and an updated rating report. For each conductor the spreadsheet calculates 72 ratings consisting of the normal, emergency and transient rating in 5° increments from -15°C to 40°C for day and night conditions. The new “PJM OHT Conductor Rating” spreadsheet is based on the overhead conductor methodology as set forth in IEEE 738-2006, “Standard for Calculating the Current Temperature of Bare Overhead Conductors”.. Copies of the standard are widely available at modest cost. Further, the method is based upon the 1958 work of House and Tuttle as modified by a group sponsored by the East Central Area Reliability Co-Ordination Agreement (ECAR) and is similar to the “PJM Method” of calculating bare overhead conductor ratings Due to the iterative process of calculating load dump the spreadsheet was written using Visual Basic in Microsoft Excel. All the parameters contained in IEEE 738-2006 may be modified in the spreadsheet. The PJM parameters listed in section 9 have been set as default. The database contains most transmission conductors in service today. The spreadsheet’s database has been designed so additional conductors may be easily added. A copy of the spreadsheet is available from PJM for all members.

Description of IEEE 738 The standard presents a method of calculating the current-temperature relationship of bare overhead conductors. The conductor temperature is a function of:

Conductor material

Conductor diameter

Conductor surface condition

Ambient weather conditions

Conductor electrical current

Page 23: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 23 of 47 Revised: 03/01/10

This standard includes mathematical methods for the calculation of conductor temperatures and conductor thermal ratings. Due to a great diversity of weather conditions and operating circumstances for which conductor temperatures and/or thermal ratings must be calculated, the standard does not list actual temperature-current relationships for specific conductors or weather conditions. Each user must make an assessment of which weather data and conductor characteristics are appropriate. The equations relating electrical current to conductor temperature may be used in either of the following two ways:

To calculate the conductor temperature when the electrical current is known

To calculate the current that yields a given maximum allowable conductor temperature

The calculation methods developed in this standard are also valid for the calculation of conductor temperature under fault conditions.

Instructions for using the PJM OHT Conductor Ratings Spreadsheet To run the program, we follow the following steps:

1. Open the spreadsheet and click on “Select Conductor.” A new window for “Calculation Set Up” opens up.

Page 24: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 24 of 47 Revised: 03/01/10

2. Choose the type of the conductor from the given list under the “Conductor Type” section.

3. Click on the name of the conductor from the given list under the “Name of Conductor” section.

4. Review the month, day, time and atmospheric conditions parameters. The spreadsheet defaults to the PJM values. Adjust parameters as required and click “Select”

5. To calculate the rating of the conductor click “Calculate” on the spread sheet. 6. Click on “Export.” This will save the report to your current desktop.

Page 25: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 25 of 47 Revised: 03/01/10

7. To get the ratings for another conductor, click on “Select Conductor” again, and follow the same procedure. The report will be saved in a new spreadsheet on the desktop.

8. To add a conductor which is not on the list, click on “Add Conductor” on the

spreadsheet. Input the information and click on “Add Conductor.” To add the entry manually, click on “Manual Entry.”

The PJM parameters listed in section 9 have been set as default but all the parameters of IEEE 738-2006 may be modified in the spreadsheet. The max allowable conductor temperatures for the various conductor specifications can be modified by double clicking on the values in the “Data Input” workbook.

Comparison of the PJM OHT Conductor Rating Spreadsheet A comparison was made between the results of the PJM Ratings spreadsheet, Rate Kit and PLS Cadd using 795 ACSR 26/7 “Drake” conductor. The maximum conductor operating temperature was chosen to be 140 °C and the AC resistance of the conductor was fixed at 0.177Ω/1000 ft @25 °C and 0.139Ω/1000 ft @75 °C for all runs. All other parameters were set to the PJM default values listed in section 9. The results between the PJM spreadsheet and the two programs varied by less than 1%. Figure 12-1 shows the results of the comparison.

Page 26: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 26 of 47 Revised: 03/01/10

A second comparison of the spreadsheet was performed with the PJM OHT Ratings Spreadsheet and Ratekit using several different conductors and maximum operating temperatures. The deviation between the two methods was found to be less than 1%. Figure 12-2 shows the results of the comparison.

Page 27: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 27 of 47 Revised: 03/01/10

Appendix 1 Frequency Distribution of Wind and Ambient Temperature

Conditions

Table 12-1 – SUMMER

AMBIENT TEMP.C 0 1 2 3 4 5 OVER 5

0 0.009 0.025 0.042 0.024 0.059 0.070 1.830

5 0.038 0.115 0.195 0.247 0.326 0.427 6.455

10 0.059 0.176 0.299 0.345 0.519 0.634 8.811

15 0.070 0.209 0.355 0.484 0.741 0.955 11.147

20 0.103 0.311 0.528 0.655 1.049 1.401 14.559

25 0.109 0.324 0.550 0.791 1.405 1.743 17.949

30 0.059 0.178 0.302 0.496 0.962 1.381 14.708

35 0.012 0.034 0.058 0.127 0.261 0.389 4.650

Over 35 0.000 0.001 0.001 0.003 0.009 0.010 0.187

0.459 1.373 2.330 3.172 5.331 7.010 80.296

AMBIENT TEMP.C 0 1 2 3 4 5 OVER 5

0 0.031 0.090 0.153 0.114 0.248 0.271 2.998

5 0.125 0.373 0.632 0.659 0.921 1.135 8.495

10 0.174 0.524 0.887 0.987 1.340 1.453 10.003

15 0.257 0.773 1.312 1.174 1.654 2.089 11.975

20 0.351 1.020 1.730 1.582 2.254 2.600 13.952

25 0.236 0.711 1.207 1.671 2.205 2.582 12.846

30 0.037 0.112 0.188 0.342 0.426 0.516 2.490

35 0.000 0.001 0.002 0.006 0.013 0.011 0.064

Over 35 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1.211 3.604 6.111 6.535 9.061 10.657 62.823

Note: Data is taken from page A-18, of 1973 PJM report,

"Determination of Thermal Ratings for Bare Overhead Conductors".

SUMMER DAYS

WIND SPEED-KNOTS

SUMMER NIGHTS

WIND SPEED-KNOTS

PITTSBURGH AND WASHINGTON D.C.

FREQUENCY OF OCCURRENCE (PERCENT)

COMPOSITE WEATHER DATA

PITTSBURGH 1/1/49 - 12/31/58 - 10 YEARS

NATIONAL AIRPORT 1/1/49 - 12/31/64 - 16 YEARS

TOTAL COMPOSITE HOURLY RECORD - 26 YEARS

Page 28: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 28 of 47 Revised: 03/01/10

FREQUENCY OF OCCURRENCE (PERCENT)

WINTER DAYS

WIND SPEED-KNOTS

AMBIENT TEMP.C 0 1 2 3 4 5 OVER 5

0 0.105 0.321 0.541 0.751 1.315 1.649 22.146

5 0.233 0.695 1.184 1.633 2.380 2.912 31.418

10 0.118 0.354 0.600 0.875 1.079 1.351 16.749

15 0.046 0.134 0.230 0.282 0.344 0.433 7.302

20 0.007 0.023 0.039 0.062 0.062 0.082 2.164

25 0.000 0.000 0.000 0.003 0.000 0.003 0.348

30 0.000 0.000 0.000 0.000 0.000 0.000 0.007

35 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Over 35 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.509 1.527 2.594 3.606 5.180 6.430 80.134

WINTER NIGHTS

WIND SPEED-KNOTS

AMBIENT TEMP.C 0 1 2 3 4 5 OVER 5

0 0.287 0.856 1.453 1.581 2.709 3.038 27.265

5 0.450 1.345 2.282 2.778 3.286 3.592 28.548

10 0.136 0.411 0.791 0.709 0.884 1.073 10.873

15 0.023 0.078 0.132 0.151 0.213 0.190 3.953

20 0.004 0.008 0.016 0.004 0.012 0.012 0.918

25 0.000 0.000 0.000 0.000 0.000 0.000 0.008

30 0.000 0.000 0.000 0.000 0.000 0.000 0.000

35 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Over 35 0.000 0.000 0.000 0.000 0.000 0.000 0.000

0.900 2.698 4.674 5.223 7.104 7.905 71.565

Note: Data is taken from page A-19, of 1973 PJM report,

"Determination of Thermal Ratings for Bare Overhead Conductors".

TOTAL COMPOSITE HOURLY RECORD - 26 YEARS

PITTSBURGH AND WASHINGTON D.C.

COMPOSITE WEATHER DATA

PITTSBURGH 1/1/49 - 12/31/58 - 10 YEARS

NATIONAL AIRPORT 1/1/49 - 12/31/64 - 16 YEARS

Table 12-2 – WINTER

Page 29: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 29 of 47 Revised: 03/01/10

PJM LOAD CYCLE

(SUMMER AND WINTER)

WEEKDAY

100

% 70

of

normal

rating

DAYLIGHT HOURS

12 M 8 AM 12 N 8 PM 12 M

AM PM

TIME OF DAY

100 WEEK END

% 70

of

normal

rating

DAYLIGHT HOURS

12 M 8 AM 12 N 8 PM 12 M

AM PM

TIME OF DAY

Figure 12-3

Page 30: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 30 of 47 Revised: 03/01/10

09.1TSTR

STSTR100

TSTR

ECSTRECRSRS

d

1.0095.0T001.0

t134T24.0ECRS

100Use100134T24.0If

Appendix 2 Example of Loss of Strength Calculations

Example of Loss of Strength Calculation for 1590 kcmil 45/7 ACSR (Lapwing) The following Temperatures and Durations were obtained from the weather model computer program developed for the 1973 PJM conductor report

Temperature (°C) Duration (Hours)

100 402

105 284

110 225

115 132

120 67

125 14

130 1

135 1

From the Paper “Effect of Elevated Temperature Operation on the Strength of Aluminum Conductors” (reference 13.1) the following equations and variables for calculating loss of strength in ACSR conductors are:

Where:

RS = Remaining strength as a percentage of initial strength.

RS EC = Remaining strength as a percentage of initial strength of the EC strands.

T = Temperature (°C)

t = Elapsed time (hours)

D = Strand diameter (inches)

STR EC = Calculated initial strength of EC strands (lb)

STR ST = Calculated initial strength of the steel core (lb)

STR T = Calculated initial strength of the conductor (lb)

Page 31: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 31 of 47 Revised: 03/01/10

RS100StrengthofLoss

%35.165.98100StrengthofLoss

%65.9809.1lb200,42

lb915,14100

lb200,42

lb285,2793RS

lb27,2850.91kip

lb1000ksi24.0in0.0277645 2

lbkip

lbksiin 915,1496.0

100018001233.07 2

lb200,42lb915,14lb285,27

Step 1 Calculate Initial Strength of the Conductor and Aluminum and Steel Components From: ASTM B232 “Standard Specification for Concentric-Lay Stranded Aluminum Conductors, Coated-Steel Reinforced (ACSR)” Aluminum 45 strands @ 0.1880" dia. ea., Area of One Strand = 0.02776 in2 , Rating Factor = 91% Average Tensile Strength (ASTM B230) = 24.0 ksi

Steel 7 strands @ 0.1253" dia. Ea. Area of One Strand = 0.01233 in2 Rating Factor = 96% Strength at 1% Elongation (ASTM B498) = 180.0 ksi Total Conductor Aluminum: (STR EC)

Steel Core: (STR ST)

Conductor: (STR T)

Step 2 Determine Remaining Strength (RS) of Aluminum Strands Using the equation for RS EC and inputting various temperatures and durations into an Excel spreadsheet, curves (% Remaining Strength vs. Hours) for each temperature can be developed. Then using these curves, the remaining strength of the aluminum strands can be determined.

402 hrs at 100°C results in RS = 98% is equivalent to 20 hrs at 105°C

284 + 20 hrs at 105°C results in RS = 97% is equivalent to 47 hrs at 110°C 225 + 47 hrs at 110°C results in RS = 96% is equivalent to73 hrs at 115°C 132 + 73 hrs at 115°C results in RS = 94% is equivalent to 74 hrs at 120°C 67 + 74 hrs at 120°C results in RS = 94% is equivalent to 61 hrs at 125°C 14 + 61 hrs at 125°C results in RS = 93% is equivalent to 39 hrs at 130°C 1 + 39 hrs at 130°C results in RS = 93% is equivalent to 26 hrs at 135°C 1 + 26 hrs at 135°C results in RS = 93%

Step 3 Determine The Remaining Strength of the Conductor

Step 4 Determine Loss of Strength of the Conductor

09.1TSTR

STSTR100

TSTR

ECSTRECRSRS

Page 32: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 32 of 47 Revised: 03/01/10

Steady State Thermal Ratings

336 26/7 ACSR - Linnet Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 657 639 621 603 584 565 545 525 504 482 459 435

Emerg 2.533 100 867 848 829 809 789 768 746 723 700 675 649 622

Normal 0 110 687 671 654 637 620 602 584 565 545 525 504 483

Emerg 2.533 110 898 880 862 844 825 805 785 764 743 720 697 672

Normal 0 120 717 701 685 669 653 636 619 601 583 565 546 526

Emerg 2.533 120 927 910 893 876 858 840 821 802 782 761 740 718

Normal 0 125 731 716 700 685 669 652 636 619 602 584 565 546

Emerg 2.533 125 940 924 908 891 874 857 838 820 801 781 760 739

Normal 0 130 744 730 715 700 684 668 652 636 619 602 584 566

Emerg 2.533 130 954 938 923 906 890 873 855 837 818 799 780 759

Normal 0 140 771 757 743 728 714 699 684 668 653 636 620 603

Emerg 2.533 140 980 965 950 935 919 903 887 870 853 835 816 797

Normal 0 150 796 783 770 756 742 728 714 699 684 669 654 638

Emerg 2.533 150 1005 991 977 962 948 932 917 901 885 868 851 833

Normal 0 160 821 809 796 783 770 756 743 729 715 700 686 671

Emerg 2.533 160 1029 1016 1002 989 975 960 946 931 915 900 883 867

Normal 0 170 845 833 821 809 796 783 770 757 744 730 716 702

Emerg 2.533 170 1052 1040 1027 1014 1001 987 973 959 944 930 914 899

Normal 0 180 869 857 845 833 822 809 797 785 772 759 746 732

Emerg 2.533 180 1075 1063 1051 1038 1026 1013 1000 986 972 958 944 929

DAY - Steady State Thermal Rating (Ampacity), Amperes

336 26/7 ACSR - Linnet Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 695 679 662 645 627 609 591 572 553 533 512 491

Emerg 2.533 100 896 878 860 841 821 801 780 758 736 712 688 663

Normal 0 110 723 707 692 675 659 642 625 607 589 571 552 532

Emerg 2.533 110 925 908 891 873 855 836 816 796 776 754 732 709

Normal 0 120 750 735 720 705 689 673 657 641 624 606 589 570

Emerg 2.533 120 953 937 920 903 886 869 850 832 813 793 772 751

Normal 0 125 763 748 734 719 704 688 673 657 640 623 606 589

Emerg 2.533 125 966 950 934 918 901 884 867 849 830 811 791 771

Normal 0 130 775 761 747 733 718 703 688 672 656 640 623 606

Emerg 2.533 130 978 963 948 932 916 899 882 865 847 828 809 790

Normal 0 140 800 787 773 759 745 731 717 702 687 672 656 640

Emerg 2.533 140 1003 989 974 959 944 929 912 896 879 862 844 826

Normal 0 150 824 811 798 785 772 758 745 731 716 702 687 672

Emerg 2.533 150 1027 1014 1000 985 971 956 941 926 910 894 877 860

Normal 0 160 847 835 823 810 798 785 772 758 745 731 717 703

Emerg 2.533 160 1050 1037 1024 1011 997 983 969 954 939 924 908 892

Normal 0 170 870 858 846 834 822 810 798 785 772 759 746 732

Emerg 2.533 170 1072 1060 1048 1035 1022 1008 995 981 967 952 937 922

Normal 0 180 892 881 870 858 846 835 823 811 798 786 773 760

Emerg 2.533 180 1094 1082 1070 1058 1046 1033 1020 1007 993 980 966 951

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 33: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 33 of 47 Revised: 03/01/10

556 24/7 ACSR - Parakeet Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 984 961 937 913 888 863 838 811 784 756 727 697

Emerg 2.533 100 1235 1211 1185 1159 1132 1105 1076 1046 1016 983 950 915

Normal 0 110 1024 1002 980 957 934 910 886 861 836 810 783 755

Emerg 2.533 110 1276 1253 1229 1205 1179 1154 1127 1100 1071 1042 1011 979

Normal 0 120 1062 1041 1020 999 977 955 932 909 885 861 836 810

Emerg 2.533 120 1314 1292 1270 1247 1224 1199 1175 1149 1123 1095 1067 1038

Normal 0 125 1080 1060 1040 1019 998 976 954 932 909 885 861 836

Emerg 2.533 125 1333 1311 1290 1267 1245 1221 1197 1173 1147 1121 1094 1066

Normal 0 130 1099 1079 1059 1039 1018 997 976 954 931 909 885 861

Emerg 2.533 130 1351 1330 1309 1287 1265 1243 1219 1195 1171 1146 1119 1092

Normal 0 140 1134 1115 1096 1077 1057 1037 1017 996 975 954 932 909

Emerg 2.533 140 1386 1366 1346 1326 1305 1284 1262 1239 1216 1193 1168 1143

Normal 0 150 1168 1150 1132 1114 1095 1076 1057 1037 1017 997 976 955

Emerg 2.533 150 1419 1401 1382 1363 1343 1323 1302 1281 1259 1237 1214 1191

Normal 0 160 1202 1185 1167 1150 1132 1114 1095 1077 1058 1039 1019 999

Emerg 2.533 160 1452 1434 1416 1398 1379 1360 1341 1321 1300 1279 1258 1236

Normal 0 170 1234 1218 1201 1184 1167 1150 1133 1115 1097 1079 1060 1041

Emerg 2.533 170 1484 1467 1450 1432 1415 1396 1378 1359 1340 1320 1299 1279

Normal 0 180 1266 1250 1234 1218 1202 1186 1169 1152 1135 1117 1099 1081

Emerg 2.533 180 1515 1499 1482 1466 1449 1431 1414 1396 1377 1359 1339 1320

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

556 24/7 ACSR - Parakeet Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 927 903 878 852 826 799 771 742 712 681 648 614

Emerg 2.533 100 1191 1165 1139 1112 1084 1055 1025 993 961 927 891 854

Normal 0 110 971 948 925 901 876 851 825 798 771 743 713 683

Emerg 2.533 110 1234 1210 1186 1160 1134 1107 1080 1051 1021 990 958 924

Normal 0 120 1013 991 969 946 923 900 876 851 826 800 773 745

Emerg 2.533 120 1275 1252 1229 1206 1181 1156 1131 1104 1077 1048 1019 988

Normal 0 125 1033 1012 990 968 946 923 900 876 852 826 800 774

Emerg 2.533 125 1294 1273 1250 1227 1204 1180 1155 1129 1103 1075 1047 1018

Normal 0 130 1053 1032 1011 990 968 946 923 900 877 852 827 802

Emerg 2.533 130 1313 1292 1271 1248 1226 1202 1178 1153 1128 1102 1074 1046

Normal 0 140 1091 1071 1051 1031 1011 990 969 947 925 902 879 855

Emerg 2.533 140 1350 1330 1310 1289 1268 1246 1223 1200 1176 1152 1126 1100

Normal 0 150 1128 1109 1090 1071 1052 1032 1012 991 970 949 927 905

Emerg 2.533 150 1386 1367 1348 1328 1308 1287 1266 1244 1222 1199 1175 1151

Normal 0 160 1163 1145 1127 1109 1091 1072 1053 1034 1014 994 973 952

Emerg 2.533 160 1420 1402 1384 1365 1346 1326 1306 1286 1265 1243 1221 1198

Normal 0 170 1198 1181 1164 1146 1129 1111 1093 1074 1056 1036 1017 997

Emerg 2.533 170 1453 1436 1419 1401 1383 1364 1345 1326 1306 1286 1265 1243

Normal 0 180 1231 1215 1199 1182 1165 1148 1131 1114 1096 1078 1059 1040

Emerg 2.533 180 1486 1469 1453 1436 1418 1401 1383 1364 1345 1326 1306 1286

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 34: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 34 of 47 Revised: 03/01/10

795 26/7 ACSR - Drake Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1200 1168 1136 1103 1069 1034 998 961 922 882 840 796

Emerg 2.533 100 1508 1476 1442 1408 1372 1336 1298 1258 1217 1174 1128 1081

Normal 0 110 1258 1228 1198 1167 1135 1102 1069 1035 999 963 925 885

Emerg 2.533 110 1564 1534 1503 1471 1438 1404 1369 1332 1295 1255 1214 1172

Normal 0 120 1312 1284 1256 1227 1197 1167 1136 1104 1071 1037 1002 966

Emerg 2.533 120 1617 1589 1560 1530 1499 1467 1435 1401 1366 1330 1293 1254

Normal 0 125 1339 1312 1284 1256 1227 1197 1167 1137 1105 1072 1039 1004

Emerg 2.533 125 1643 1615 1587 1558 1528 1498 1466 1434 1400 1366 1330 1292

Normal 0 130 1365 1338 1311 1284 1256 1227 1198 1168 1138 1106 1074 1041

Emerg 2.533 130 1668 1641 1613 1585 1557 1527 1497 1465 1433 1400 1365 1329

Normal 0 140 1415 1390 1364 1338 1312 1285 1258 1230 1201 1172 1141 1110

Emerg 2.533 140 1716 1691 1665 1638 1611 1583 1555 1526 1495 1464 1432 1399

Normal 0 150 1463 1439 1415 1391 1366 1340 1314 1288 1261 1233 1205 1176

Emerg 2.533 150 1762 1738 1714 1689 1663 1637 1610 1583 1555 1526 1496 1465

Normal 0 160 1510 1487 1464 1441 1417 1393 1368 1343 1318 1292 1265 1238

Emerg 2.533 160 1807 1785 1761 1738 1713 1689 1663 1637 1611 1584 1555 1527

Normal 0 170 1556 1534 1512 1490 1467 1444 1421 1397 1373 1348 1323 1297

Emerg 2.533 170 1851 1829 1807 1785 1762 1738 1714 1690 1665 1639 1612 1585

Normal 0 180 1600 1580 1558 1537 1516 1494 1471 1449 1426 1403 1379 1354

Emerg 2.533 180 1893 1873 1852 1830 1808 1786 1763 1740 1716 1692 1667 1642

DAY - Steady State Thermal Rating (Ampacity), Amperes

795 26/7 ACSR - Drake Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1275 1246 1215 1185 1153 1121 1087 1053 1018 982 945 906

Emerg 2.533 100 1569 1538 1506 1473 1439 1404 1368 1330 1291 1251 1208 1164

Normal 0 110 1328 1300 1271 1242 1212 1182 1151 1119 1086 1053 1018 982

Emerg 2.533 110 1621 1592 1562 1531 1500 1467 1434 1399 1363 1326 1287 1247

Normal 0 120 1378 1351 1324 1297 1269 1240 1211 1181 1150 1119 1087 1054

Emerg 2.533 120 1671 1643 1615 1586 1557 1526 1495 1463 1429 1395 1359 1322

Normal 0 125 1402 1376 1350 1323 1296 1268 1240 1211 1181 1151 1119 1087

Emerg 2.533 125 1695 1668 1641 1613 1584 1555 1524 1493 1461 1428 1394 1358

Normal 0 130 1426 1401 1375 1349 1323 1295 1268 1240 1211 1181 1151 1120

Emerg 2.533 130 1718 1692 1666 1639 1611 1582 1553 1523 1492 1460 1427 1392

Normal 0 140 1473 1449 1424 1399 1374 1348 1322 1296 1269 1241 1212 1183

Emerg 2.533 140 1764 1739 1714 1689 1662 1635 1608 1579 1550 1520 1490 1458

Normal 0 150 1518 1495 1472 1448 1424 1400 1375 1349 1324 1298 1271 1243

Emerg 2.533 150 1808 1785 1761 1737 1712 1686 1660 1634 1606 1578 1549 1519

Normal 0 160 1562 1540 1518 1495 1472 1449 1425 1401 1377 1352 1327 1301

Emerg 2.533 160 1851 1828 1806 1783 1759 1735 1710 1685 1659 1633 1606 1578

Normal 0 170 1605 1584 1562 1541 1519 1497 1474 1451 1428 1404 1380 1356

Emerg 2.533 170 1892 1871 1849 1828 1805 1782 1759 1735 1711 1685 1660 1633

Normal 0 180 1647 1627 1606 1586 1565 1543 1522 1500 1478 1455 1432 1409

Emerg 2.533 180 1933 1913 1892 1871 1850 1828 1806 1783 1760 1736 1712 1687

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 35: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 35 of 47 Revised: 03/01/10

795 30/19 ACSR - Mallard Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1295 1265 1234 1203 1171 1138 1104 1070 1034 997 959 920

Emerg 2.533 100 1588 1557 1524 1491 1457 1421 1385 1347 1307 1266 1224 1179

Normal 0 110 1348 1320 1291 1261 1231 1200 1169 1136 1103 1069 1034 998

Emerg 2.533 110 1641 1611 1581 1550 1518 1485 1451 1416 1380 1342 1303 1262

Normal 0 120 1399 1372 1345 1317 1288 1259 1230 1199 1168 1136 1104 1070

Emerg 2.533 120 1691 1663 1635 1606 1576 1545 1514 1481 1447 1412 1376 1339

Normal 0 125 1424 1397 1371 1343 1316 1288 1259 1229 1199 1168 1137 1104

Emerg 2.533 125 1715 1688 1661 1633 1604 1574 1543 1512 1479 1446 1411 1375

Normal 0 130 1448 1422 1396 1370 1343 1315 1287 1259 1230 1200 1169 1138

Emerg 2.533 130 1739 1713 1686 1659 1631 1602 1572 1542 1510 1478 1444 1410

Normal 0 140 1495 1471 1446 1421 1395 1369 1343 1316 1288 1260 1231 1202

Emerg 2.533 140 1785 1761 1735 1709 1683 1656 1628 1599 1570 1539 1508 1476

Normal 0 150 1541 1518 1494 1470 1446 1421 1396 1370 1344 1317 1290 1262

Emerg 2.533 150 1830 1806 1782 1758 1733 1707 1681 1654 1626 1598 1568 1538

Normal 0 160 1585 1563 1541 1518 1494 1471 1447 1423 1398 1373 1347 1321

Emerg 2.533 160 1873 1851 1828 1805 1781 1756 1732 1706 1680 1653 1626 1597

Normal 0 170 1629 1608 1586 1564 1542 1519 1497 1473 1450 1426 1401 1377

Emerg 2.533 170 1915 1894 1872 1850 1827 1804 1781 1756 1732 1706 1680 1654

Normal 0 180 1672 1651 1630 1609 1588 1567 1545 1523 1500 1478 1454 1431

Emerg 2.533 180 1956 1936 1915 1894 1872 1850 1828 1805 1782 1758 1733 1708

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

795 30/19 ACSR - Mallard Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1218 1186 1153 1119 1085 1049 1013 975 936 895 852 808

Emerg 2.533 100 1526 1493 1459 1425 1389 1352 1313 1273 1231 1187 1142 1094

Normal 0 110 1276 1246 1216 1184 1152 1119 1085 1050 1014 977 939 898

Emerg 2.533 110 1583 1552 1521 1488 1455 1421 1385 1348 1310 1270 1229 1186

Normal 0 120 1332 1304 1275 1245 1215 1184 1153 1120 1087 1053 1017 981

Emerg 2.533 120 1636 1608 1578 1548 1517 1485 1452 1418 1383 1346 1308 1269

Normal 0 125 1359 1331 1303 1275 1245 1216 1185 1154 1122 1089 1055 1019

Emerg 2.533 125 1662 1634 1606 1576 1546 1515 1484 1451 1417 1382 1346 1308

Normal 0 130 1385 1358 1331 1303 1275 1246 1216 1186 1155 1123 1090 1057

Emerg 2.533 130 1687 1660 1633 1604 1575 1545 1514 1483 1450 1416 1381 1345

Normal 0 140 1436 1411 1385 1358 1332 1304 1277 1248 1219 1189 1159 1127

Emerg 2.533 140 1736 1711 1685 1658 1631 1602 1574 1544 1513 1482 1450 1416

Normal 0 150 1485 1461 1436 1411 1386 1360 1334 1307 1280 1252 1223 1194

Emerg 2.533 150 1783 1759 1734 1709 1683 1657 1630 1602 1573 1544 1514 1482

Normal 0 160 1533 1510 1486 1463 1438 1414 1389 1364 1338 1311 1284 1257

Emerg 2.533 160 1829 1806 1782 1758 1734 1709 1683 1657 1630 1603 1574 1545

Normal 0 170 1579 1557 1535 1512 1489 1466 1442 1418 1394 1369 1343 1317

Emerg 2.533 170 1873 1851 1829 1806 1783 1759 1735 1710 1685 1659 1632 1605

Normal 0 180 1624 1603 1582 1560 1538 1516 1494 1471 1447 1424 1400 1375

Emerg 2.533 180 1916 1895 1874 1852 1830 1808 1785 1761 1737 1713 1687 1662

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 36: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 36 of 47 Revised: 03/01/10

795 30/19 ACSR - Mallard Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1295 1265 1234 1203 1171 1138 1104 1070 1034 997 959 920

Emerg 2.533 100 1588 1557 1524 1491 1457 1421 1385 1347 1307 1266 1224 1179

Normal 0 110 1348 1320 1291 1261 1231 1200 1169 1136 1103 1069 1034 998

Emerg 2.533 110 1641 1611 1581 1550 1518 1485 1451 1416 1380 1342 1303 1262

Normal 0 120 1399 1372 1345 1317 1288 1259 1230 1199 1168 1136 1104 1070

Emerg 2.533 120 1691 1663 1635 1606 1576 1545 1514 1481 1447 1412 1376 1339

Normal 0 125 1424 1397 1371 1343 1316 1288 1259 1229 1199 1168 1137 1104

Emerg 2.533 125 1715 1688 1661 1633 1604 1574 1543 1512 1479 1446 1411 1375

Normal 0 130 1448 1422 1396 1370 1343 1315 1287 1259 1230 1200 1169 1138

Emerg 2.533 130 1739 1713 1686 1659 1631 1602 1572 1542 1510 1478 1444 1410

Normal 0 140 1495 1471 1446 1421 1395 1369 1343 1316 1288 1260 1231 1202

Emerg 2.533 140 1785 1761 1735 1709 1683 1656 1628 1599 1570 1539 1508 1476

Normal 0 150 1541 1518 1494 1470 1446 1421 1396 1370 1344 1317 1290 1262

Emerg 2.533 150 1830 1806 1782 1758 1733 1707 1681 1654 1626 1598 1568 1538

Normal 0 160 1585 1563 1541 1518 1494 1471 1447 1423 1398 1373 1347 1321

Emerg 2.533 160 1873 1851 1828 1805 1781 1756 1732 1706 1680 1653 1626 1597

Normal 0 170 1629 1608 1586 1564 1542 1519 1497 1473 1450 1426 1401 1377

Emerg 2.533 170 1915 1894 1872 1850 1827 1804 1781 1756 1732 1706 1680 1654

Normal 0 180 1672 1651 1630 1609 1588 1567 1545 1523 1500 1478 1454 1431

Emerg 2.533 180 1956 1936 1915 1894 1872 1850 1828 1805 1782 1758 1733 1708

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

795 30/19 ACSR - Mallard Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1218 1186 1153 1119 1085 1049 1013 975 936 895 852 808

Emerg 2.533 100 1526 1493 1459 1425 1389 1352 1313 1273 1231 1187 1142 1094

Normal 0 110 1276 1246 1216 1184 1152 1119 1085 1050 1014 977 939 898

Emerg 2.533 110 1583 1552 1521 1488 1455 1421 1385 1348 1310 1270 1229 1186

Normal 0 120 1332 1304 1275 1245 1215 1184 1153 1120 1087 1053 1017 981

Emerg 2.533 120 1636 1608 1578 1548 1517 1485 1452 1418 1383 1346 1308 1269

Normal 0 125 1359 1331 1303 1275 1245 1216 1185 1154 1122 1089 1055 1019

Emerg 2.533 125 1662 1634 1606 1576 1546 1515 1484 1451 1417 1382 1346 1308

Normal 0 130 1385 1358 1331 1303 1275 1246 1216 1186 1155 1123 1090 1057

Emerg 2.533 130 1687 1660 1633 1604 1575 1545 1514 1483 1450 1416 1381 1345

Normal 0 140 1436 1411 1385 1358 1332 1304 1277 1248 1219 1189 1159 1127

Emerg 2.533 140 1736 1711 1685 1658 1631 1602 1574 1544 1513 1482 1450 1416

Normal 0 150 1485 1461 1436 1411 1386 1360 1334 1307 1280 1252 1223 1194

Emerg 2.533 150 1783 1759 1734 1709 1683 1657 1630 1602 1573 1544 1514 1482

Normal 0 160 1533 1510 1486 1463 1438 1414 1389 1364 1338 1311 1284 1257

Emerg 2.533 160 1829 1806 1782 1758 1734 1709 1683 1657 1630 1603 1574 1545

Normal 0 170 1579 1557 1535 1512 1489 1466 1442 1418 1394 1369 1343 1317

Emerg 2.533 170 1873 1851 1829 1806 1783 1759 1735 1710 1685 1659 1632 1605

Normal 0 180 1624 1603 1582 1560 1538 1516 1494 1471 1447 1424 1400 1375

Emerg 2.533 180 1916 1895 1874 1852 1830 1808 1785 1761 1737 1713 1687 1662

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 37: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 37 of 47 Revised: 03/01/10

1033.5 45/7 ACSR - Ortolan Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1397 1360 1322 1284 1244 1204 1162 1118 1073 1027 978 926

Emerg 2.533 100 1738 1701 1662 1623 1582 1540 1496 1450 1402 1353 1300 1245

Normal 0 110 1464 1429 1394 1358 1321 1284 1245 1205 1164 1121 1077 1031

Emerg 2.533 110 1803 1768 1732 1695 1658 1618 1578 1536 1492 1447 1400 1351

Normal 0 120 1528 1495 1462 1428 1394 1359 1322 1285 1247 1208 1167 1125

Emerg 2.533 120 1864 1831 1798 1764 1728 1692 1654 1616 1575 1534 1491 1446

Normal 0 125 1558 1527 1495 1462 1428 1394 1359 1324 1287 1249 1210 1170

Emerg 2.533 125 1894 1862 1829 1796 1762 1727 1691 1653 1615 1575 1533 1490

Normal 0 130 1588 1558 1527 1495 1462 1429 1395 1361 1325 1289 1251 1212

Emerg 2.533 130 1922 1892 1860 1828 1795 1761 1726 1690 1653 1614 1574 1533

Normal 0 140 1647 1618 1588 1558 1527 1496 1464 1432 1399 1364 1329 1293

Emerg 2.533 140 1978 1949 1920 1889 1858 1826 1793 1760 1725 1689 1652 1614

Normal 0 150 1703 1675 1647 1619 1590 1560 1530 1500 1468 1436 1403 1370

Emerg 2.533 150 2032 2005 1977 1948 1919 1888 1858 1826 1793 1760 1725 1690

Normal 0 160 1758 1731 1705 1677 1650 1622 1593 1564 1535 1505 1474 1442

Emerg 2.533 160 2084 2058 2031 2004 1976 1948 1919 1889 1859 1827 1795 1762

Normal 0 170 1811 1786 1760 1734 1708 1681 1654 1627 1599 1570 1541 1511

Emerg 2.533 170 2135 2110 2084 2059 2032 2005 1978 1950 1921 1891 1861 1830

Normal 0 180 1862 1838 1814 1789 1764 1739 1713 1687 1660 1633 1606 1578

Emerg 2.533 180 2184 2160 2136 2111 2086 2061 2035 2008 1981 1953 1924 1895

DAY - Steady State Thermal Rating (Ampacity), Amperes

1033.5 45/7 ACSR - Ortolan Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1486 1452 1417 1381 1344 1306 1268 1228 1187 1145 1102 1056

Emerg 2.533 100 1811 1775 1738 1700 1661 1621 1579 1536 1491 1445 1396 1345

Normal 0 110 1547 1514 1481 1447 1413 1378 1342 1305 1267 1228 1187 1146

Emerg 2.533 110 1871 1837 1803 1768 1731 1694 1655 1615 1574 1531 1487 1440

Normal 0 120 1605 1574 1543 1511 1478 1445 1411 1377 1341 1305 1267 1229

Emerg 2.533 120 1928 1897 1864 1831 1797 1762 1726 1689 1651 1611 1570 1528

Normal 0 125 1633 1603 1573 1542 1510 1478 1445 1411 1377 1341 1305 1268

Emerg 2.533 125 1956 1925 1894 1862 1829 1795 1760 1724 1687 1649 1610 1569

Normal 0 130 1661 1632 1602 1572 1541 1510 1478 1445 1411 1377 1342 1306

Emerg 2.533 130 1983 1953 1923 1892 1860 1827 1793 1758 1723 1686 1648 1608

Normal 0 140 1715 1687 1659 1630 1601 1571 1541 1510 1478 1446 1413 1379

Emerg 2.533 140 2036 2007 1979 1949 1919 1888 1856 1824 1790 1756 1720 1684

Normal 0 150 1768 1741 1714 1687 1659 1630 1602 1572 1543 1512 1481 1449

Emerg 2.533 150 2086 2060 2032 2004 1976 1947 1917 1886 1855 1822 1789 1755

Normal 0 160 1819 1793 1767 1741 1715 1688 1660 1633 1604 1575 1546 1516

Emerg 2.533 160 2136 2110 2084 2058 2031 2003 1975 1946 1916 1886 1855 1822

Normal 0 170 1868 1844 1819 1794 1769 1743 1717 1691 1664 1636 1608 1580

Emerg 2.533 170 2184 2160 2135 2110 2084 2058 2031 2004 1975 1947 1917 1887

Normal 0 180 1917 1894 1870 1846 1822 1798 1773 1747 1722 1696 1669 1642

Emerg 2.533 180 2231 2208 2184 2160 2136 2111 2085 2059 2032 2005 1977 1949

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 38: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 38 of 47 Revised: 03/01/10

1033.5 54/7 ACSR - Curlew Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1400 1363 1326 1287 1248 1207 1165 1121 1076 1029 980 929

Emerg 2.533 100 1737 1700 1662 1622 1581 1539 1495 1449 1402 1352 1300 1245

Normal 0 110 1465 1431 1396 1360 1323 1285 1246 1206 1165 1122 1078 1032

Emerg 2.533 110 1799 1765 1729 1692 1655 1615 1575 1533 1490 1445 1397 1348

Normal 0 120 1527 1495 1462 1428 1394 1358 1322 1285 1247 1208 1167 1125

Emerg 2.533 120 1858 1826 1792 1758 1723 1687 1649 1611 1571 1529 1486 1441

Normal 0 125 1557 1526 1493 1461 1427 1393 1358 1323 1286 1248 1209 1169

Emerg 2.533 125 1887 1855 1823 1790 1756 1721 1685 1647 1609 1569 1528 1485

Normal 0 130 1586 1556 1524 1493 1460 1427 1393 1359 1323 1287 1250 1211

Emerg 2.533 130 1914 1884 1852 1820 1787 1753 1719 1683 1646 1607 1568 1527

Normal 0 140 1643 1614 1584 1554 1524 1493 1461 1428 1395 1361 1326 1290

Emerg 2.533 140 1968 1939 1909 1879 1848 1817 1784 1750 1716 1680 1644 1606

Normal 0 150 1697 1669 1641 1613 1584 1555 1525 1494 1463 1431 1399 1365

Emerg 2.533 150 2019 1992 1964 1936 1906 1877 1846 1815 1782 1749 1715 1680

Normal 0 160 1750 1723 1697 1670 1642 1615 1586 1557 1528 1498 1467 1436

Emerg 2.533 160 2069 2043 2017 1990 1962 1934 1905 1875 1845 1814 1782 1749

Normal 0 170 1801 1776 1750 1725 1699 1672 1645 1618 1590 1562 1533 1503

Emerg 2.533 170 2117 2092 2067 2042 2016 1989 1962 1934 1905 1876 1846 1815

Normal 0 180 1850 1826 1802 1778 1753 1728 1702 1676 1650 1623 1596 1568

Emerg 2.533 180 2164 2140 2117 2092 2068 2042 2016 1990 1963 1935 1907 1878

DAY - Steady State Thermal Rating (Ampacity), Amperes

1033.5 54/7 ACSR - Curlew Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1490 1456 1421 1385 1348 1310 1272 1232 1191 1149 1105 1060

Emerg 2.533 100 1810 1775 1738 1700 1661 1621 1580 1536 1492 1445 1396 1345

Normal 0 110 1549 1516 1483 1450 1415 1380 1344 1307 1269 1230 1189 1148

Emerg 2.533 110 1868 1835 1800 1765 1729 1692 1653 1613 1572 1529 1485 1439

Normal 0 120 1605 1574 1543 1511 1479 1445 1412 1377 1341 1305 1267 1229

Emerg 2.533 120 1923 1891 1859 1826 1792 1758 1722 1685 1647 1607 1566 1524

Normal 0 125 1632 1602 1572 1541 1509 1477 1444 1411 1376 1341 1305 1268

Emerg 2.533 125 1949 1919 1888 1856 1823 1789 1754 1719 1682 1644 1605 1564

Normal 0 130 1659 1630 1600 1570 1539 1508 1476 1443 1410 1376 1341 1305

Emerg 2.533 130 1975 1946 1915 1884 1852 1820 1786 1752 1716 1679 1642 1602

Normal 0 140 1711 1683 1655 1626 1597 1568 1537 1507 1475 1443 1410 1377

Emerg 2.533 140 2025 1997 1969 1939 1909 1879 1847 1815 1782 1747 1712 1676

Normal 0 150 1762 1735 1708 1681 1653 1625 1596 1567 1537 1507 1476 1445

Emerg 2.533 150 2074 2047 2020 1992 1964 1935 1905 1875 1844 1812 1779 1745

Normal 0 160 1810 1785 1760 1734 1707 1680 1653 1625 1597 1569 1539 1509

Emerg 2.533 160 2121 2095 2070 2043 2017 1989 1961 1932 1903 1873 1842 1810

Normal 0 170 1858 1834 1810 1785 1760 1734 1708 1682 1655 1628 1600 1572

Emerg 2.533 170 2166 2142 2118 2093 2067 2041 2015 1988 1960 1931 1902 1872

Normal 0 180 1905 1882 1858 1835 1811 1786 1762 1736 1711 1685 1659 1632

Emerg 2.533 180 2211 2188 2165 2141 2117 2092 2067 2041 2015 1988 1960 1932

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 39: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 39 of 47 Revised: 03/01/10

1272 45/7 ACSR - Bittern Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1612 1570 1526 1482 1436 1389 1341 1291 1239 1185 1129 1069

Emerg 2.533 100 1983 1940 1897 1851 1805 1757 1706 1654 1600 1543 1483 1420

Normal 0 110 1690 1651 1610 1569 1526 1483 1438 1392 1344 1295 1244 1191

Emerg 2.533 110 2058 2019 1978 1936 1893 1848 1802 1754 1704 1653 1599 1542

Normal 0 120 1765 1728 1690 1651 1611 1570 1529 1486 1442 1396 1350 1301

Emerg 2.533 120 2130 2093 2055 2015 1975 1934 1891 1847 1801 1753 1704 1653

Normal 0 125 1801 1765 1728 1690 1651 1612 1572 1530 1488 1444 1399 1353

Emerg 2.533 125 2164 2128 2091 2054 2015 1974 1933 1890 1846 1801 1753 1704

Normal 0 130 1836 1801 1765 1728 1691 1653 1614 1574 1533 1491 1447 1403

Emerg 2.533 130 2198 2163 2127 2091 2053 2014 1974 1933 1890 1847 1801 1754

Normal 0 140 1905 1871 1837 1803 1767 1731 1695 1657 1619 1579 1539 1497

Emerg 2.533 140 2264 2231 2197 2162 2127 2090 2053 2014 1975 1934 1892 1848

Normal 0 150 1971 1939 1907 1874 1841 1806 1772 1736 1700 1663 1625 1587

Emerg 2.533 150 2327 2296 2264 2231 2197 2163 2128 2092 2055 2016 1977 1936

Normal 0 160 2035 2005 1974 1943 1911 1879 1846 1812 1778 1743 1708 1671

Emerg 2.533 160 2388 2358 2328 2297 2265 2233 2200 2166 2131 2095 2058 2020

Normal 0 170 2098 2069 2039 2009 1979 1948 1917 1886 1853 1820 1787 1752

Emerg 2.533 170 2447 2419 2390 2361 2331 2300 2269 2237 2204 2170 2135 2099

Normal 0 180 2158 2131 2103 2074 2045 2016 1986 1956 1926 1894 1862 1830

Emerg 2.533 180 2505 2478 2451 2423 2394 2365 2335 2305 2274 2242 2209 2175

DAY - Steady State Thermal Rating (Ampacity), Amperes

1272 45/7 ACSR - Bittern Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1717 1677 1637 1596 1553 1510 1466 1420 1373 1325 1274 1222

Emerg 2.533 100 2069 2028 1987 1944 1899 1853 1806 1757 1706 1652 1597 1539

Normal 0 110 1788 1751 1712 1674 1634 1593 1552 1509 1465 1420 1374 1326

Emerg 2.533 110 2139 2101 2062 2022 1981 1938 1894 1848 1801 1752 1702 1649

Normal 0 120 1856 1821 1785 1748 1710 1672 1633 1593 1552 1510 1467 1422

Emerg 2.533 120 2206 2170 2134 2096 2057 2017 1976 1934 1890 1845 1798 1750

Normal 0 125 1889 1855 1820 1784 1747 1710 1672 1633 1594 1553 1511 1468

Emerg 2.533 125 2238 2204 2168 2131 2094 2055 2016 1975 1933 1889 1844 1797

Normal 0 130 1922 1888 1854 1819 1784 1747 1710 1673 1634 1595 1554 1513

Emerg 2.533 130 2270 2236 2202 2166 2130 2092 2054 2014 1974 1932 1888 1843

Normal 0 140 1985 1953 1921 1887 1854 1819 1785 1749 1713 1675 1637 1599

Emerg 2.533 140 2332 2300 2267 2233 2199 2164 2128 2091 2053 2013 1973 1931

Normal 0 150 2047 2016 1985 1954 1922 1889 1856 1822 1788 1753 1717 1680

Emerg 2.533 150 2391 2361 2330 2298 2266 2232 2198 2163 2128 2091 2053 2014

Normal 0 160 2107 2078 2048 2018 1987 1956 1925 1893 1860 1827 1793 1758

Emerg 2.533 160 2449 2420 2391 2361 2330 2298 2266 2233 2199 2165 2129 2092

Normal 0 170 2166 2138 2109 2080 2051 2022 1991 1961 1930 1898 1866 1833

Emerg 2.533 170 2506 2478 2450 2421 2392 2362 2332 2300 2268 2236 2202 2167

Normal 0 180 2223 2196 2169 2141 2113 2085 2056 2027 1998 1968 1937 1906

Emerg 2.533 180 2561 2535 2508 2481 2453 2424 2395 2366 2335 2304 2272 2240

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 40: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 40 of 47 Revised: 03/01/10

1272 54/19 ACSR - Pheasant Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1613 1571 1527 1483 1437 1391 1342 1292 1240 1186 1130 1070

Emerg 2.533 100 1978 1936 1892 1847 1801 1753 1703 1650 1596 1539 1480 1417

Normal 0 110 1689 1649 1609 1568 1525 1482 1437 1391 1344 1294 1243 1190

Emerg 2.533 110 2051 2011 1971 1929 1886 1841 1795 1748 1698 1647 1593 1537

Normal 0 120 1761 1724 1686 1647 1608 1567 1525 1483 1439 1394 1347 1298

Emerg 2.533 120 2119 2082 2044 2005 1965 1924 1881 1837 1792 1745 1695 1644

Normal 0 125 1796 1760 1723 1685 1647 1608 1567 1526 1484 1440 1396 1349

Emerg 2.533 125 2152 2116 2080 2042 2003 1963 1922 1880 1836 1791 1744 1695

Normal 0 130 1830 1795 1759 1722 1685 1647 1608 1569 1528 1486 1443 1398

Emerg 2.533 130 2184 2150 2114 2077 2040 2001 1962 1921 1879 1835 1790 1743

Normal 0 140 1896 1863 1829 1794 1759 1723 1687 1649 1611 1572 1532 1491

Emerg 2.533 140 2247 2214 2180 2146 2111 2075 2038 1999 1960 1920 1878 1835

Normal 0 150 1959 1928 1896 1863 1830 1796 1761 1726 1690 1654 1616 1578

Emerg 2.533 150 2307 2276 2244 2212 2179 2145 2110 2074 2037 1999 1960 1920

Normal 0 160 2021 1991 1960 1929 1898 1866 1833 1800 1766 1731 1696 1660

Emerg 2.533 160 2365 2335 2305 2275 2243 2211 2179 2145 2110 2075 2038 2001

Normal 0 170 2081 2052 2023 1993 1963 1933 1902 1871 1838 1806 1772 1738

Emerg 2.533 170 2421 2393 2365 2336 2306 2276 2245 2213 2180 2147 2113 2077

Normal 0 180 2139 2111 2084 2055 2027 1998 1969 1939 1908 1877 1846 1814

Emerg 2.533 180 2476 2449 2422 2395 2367 2338 2308 2278 2248 2216 2184 2150

DAY - Steady State Thermal Rating (Ampacity), Amperes

1272 54/19 ACSR - Pheasant Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1719 1679 1639 1597 1555 1512 1467 1422 1375 1326 1276 1224

Emerg 2.533 100 2065 2025 1983 1940 1896 1850 1803 1754 1703 1650 1594 1536

Normal 0 110 1787 1750 1712 1673 1633 1593 1551 1509 1465 1420 1374 1326

Emerg 2.533 110 2132 2094 2055 2015 1974 1932 1888 1843 1796 1747 1696 1644

Normal 0 120 1853 1817 1781 1745 1707 1669 1630 1590 1549 1508 1464 1420

Emerg 2.533 120 2196 2160 2124 2086 2048 2008 1967 1925 1882 1837 1790 1742

Normal 0 125 1884 1850 1815 1779 1743 1706 1668 1629 1590 1549 1508 1465

Emerg 2.533 125 2226 2192 2156 2120 2083 2044 2005 1964 1923 1879 1835 1788

Normal 0 130 1916 1882 1848 1813 1778 1742 1705 1668 1629 1590 1550 1508

Emerg 2.533 130 2257 2223 2189 2153 2117 2080 2042 2003 1962 1920 1877 1833

Normal 0 140 1976 1944 1912 1879 1845 1811 1777 1741 1705 1668 1630 1592

Emerg 2.533 140 2315 2283 2251 2217 2183 2148 2113 2076 2038 1999 1959 1918

Normal 0 150 2035 2005 1974 1942 1911 1878 1845 1812 1778 1743 1707 1671

Emerg 2.533 150 2371 2341 2310 2279 2247 2214 2180 2146 2110 2074 2036 1997

Normal 0 160 2092 2063 2034 2004 1974 1943 1912 1880 1847 1814 1781 1746

Emerg 2.533 160 2426 2397 2368 2339 2308 2277 2245 2212 2179 2145 2109 2073

Normal 0 170 2148 2121 2092 2064 2035 2006 1976 1946 1915 1883 1852 1819

Emerg 2.533 170 2479 2452 2424 2396 2367 2338 2308 2277 2245 2213 2179 2145

Normal 0 180 2203 2176 2150 2122 2095 2067 2038 2009 1980 1950 1920 1889

Emerg 2.533 180 2532 2506 2479 2452 2425 2397 2368 2339 2309 2278 2247 2214

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 41: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 41 of 47 Revised: 03/01/10

1590 45/7 ACSR - Lapwing Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1875 1826 1776 1724 1671 1617 1561 1502 1442 1379 1314 1244

Emerg 2.533 100 2279 2230 2180 2128 2074 2019 1961 1901 1839 1773 1704 1632

Normal 0 110 1968 1922 1875 1827 1777 1727 1675 1621 1566 1509 1449 1387

Emerg 2.533 110 2368 2322 2275 2227 2178 2126 2073 2018 1961 1901 1839 1774

Normal 0 120 2056 2013 1968 1923 1877 1830 1781 1732 1681 1628 1573 1517

Emerg 2.533 120 2452 2409 2366 2321 2274 2227 2177 2127 2074 2019 1962 1903

Normal 0 125 2099 2057 2014 1970 1925 1879 1832 1784 1735 1684 1632 1578

Emerg 2.533 125 2493 2452 2409 2366 2321 2275 2227 2178 2127 2075 2020 1964

Normal 0 130 2141 2100 2058 2015 1972 1927 1882 1836 1788 1739 1688 1636

Emerg 2.533 130 2533 2493 2452 2409 2366 2321 2275 2228 2179 2129 2076 2022

Normal 0 140 2222 2183 2143 2103 2062 2020 1978 1934 1889 1843 1796 1748

Emerg 2.533 140 2610 2572 2534 2494 2453 2411 2368 2324 2278 2231 2183 2133

Normal 0 150 2300 2263 2226 2187 2149 2109 2069 2028 1986 1943 1899 1853

Emerg 2.533 150 2685 2649 2613 2575 2537 2497 2457 2415 2372 2328 2283 2236

Normal 0 160 2376 2341 2305 2269 2232 2195 2156 2118 2078 2037 1996 1953

Emerg 2.533 160 2758 2723 2689 2653 2617 2580 2541 2502 2462 2421 2378 2335

Normal 0 170 2451 2417 2383 2348 2313 2277 2241 2204 2167 2128 2089 2049

Emerg 2.533 170 2828 2796 2763 2729 2694 2659 2623 2586 2548 2509 2469 2428

Normal 0 180 2523 2491 2458 2425 2392 2358 2323 2288 2252 2216 2179 2141

Emerg 2.533 180 2897 2866 2835 2802 2770 2736 2702 2667 2631 2594 2557 2518

DAY - Steady State Thermal Rating (Ampacity), Amperes

1590 45/7 ACSR - Lapwing Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2000 1954 1907 1859 1810 1760 1708 1655 1601 1544 1486 1425

Emerg 2.533 100 2382 2336 2288 2239 2188 2135 2081 2024 1966 1904 1841 1774

Normal 0 110 2084 2040 1996 1951 1905 1858 1810 1760 1709 1657 1603 1547

Emerg 2.533 110 2465 2421 2376 2330 2283 2234 2183 2131 2077 2021 1963 1902

Normal 0 120 2164 2123 2081 2039 1995 1951 1905 1859 1811 1763 1712 1661

Emerg 2.533 120 2544 2503 2460 2417 2373 2327 2280 2231 2181 2129 2076 2020

Normal 0 125 2204 2163 2123 2081 2039 1996 1952 1907 1860 1813 1765 1715

Emerg 2.533 125 2582 2542 2501 2459 2416 2372 2326 2279 2231 2181 2129 2075

Normal 0 130 2242 2203 2163 2123 2082 2040 1997 1953 1908 1862 1815 1767

Emerg 2.533 130 2619 2580 2541 2500 2458 2415 2371 2326 2279 2231 2181 2129

Normal 0 140 2317 2280 2242 2204 2165 2125 2084 2043 2001 1958 1913 1868

Emerg 2.533 140 2692 2655 2618 2579 2540 2500 2458 2415 2372 2326 2280 2232

Normal 0 150 2390 2355 2319 2282 2245 2207 2169 2129 2089 2049 2007 1964

Emerg 2.533 150 2763 2728 2692 2656 2619 2580 2541 2501 2460 2417 2374 2329

Normal 0 160 2462 2428 2393 2358 2323 2287 2250 2213 2175 2136 2097 2056

Emerg 2.533 160 2831 2798 2764 2730 2694 2658 2621 2583 2544 2505 2464 2421

Normal 0 170 2531 2499 2466 2432 2398 2364 2329 2294 2257 2221 2183 2145

Emerg 2.533 170 2898 2867 2835 2802 2768 2734 2699 2663 2626 2588 2550 2510

Normal 0 180 2600 2568 2537 2505 2472 2440 2406 2372 2338 2303 2267 2231

Emerg 2.533 180 2964 2934 2903 2872 2840 2807 2774 2740 2705 2669 2632 2595

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 42: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 42 of 47 Revised: 03/01/10

1590 54/19 ACSR - Falcon Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 1880 1831 1780 1729 1676 1621 1565 1506 1446 1383 1317 1248

Emerg 2.533 100 2278 2229 2179 2127 2074 2018 1960 1900 1838 1772 1704 1631

Normal 0 110 1970 1924 1877 1829 1779 1729 1677 1623 1568 1510 1451 1389

Emerg 2.533 110 2363 2318 2271 2223 2174 2122 2069 2014 1957 1898 1836 1771

Normal 0 120 2055 2012 1968 1923 1877 1829 1781 1731 1680 1627 1573 1517

Emerg 2.533 120 2444 2402 2358 2313 2267 2220 2171 2120 2067 2013 1956 1897

Normal 0 125 2097 2054 2012 1968 1923 1877 1831 1783 1733 1683 1630 1576

Emerg 2.533 125 2483 2442 2400 2357 2312 2266 2219 2170 2119 2067 2013 1956

Normal 0 130 2137 2096 2054 2012 1968 1924 1879 1833 1785 1736 1686 1634

Emerg 2.533 130 2521 2482 2441 2399 2355 2311 2265 2218 2170 2119 2067 2013

Normal 0 140 2215 2176 2137 2097 2056 2014 1972 1928 1884 1838 1791 1743

Emerg 2.533 140 2595 2558 2519 2480 2439 2398 2355 2311 2266 2219 2171 2121

Normal 0 150 2291 2254 2216 2178 2140 2100 2060 2019 1978 1935 1891 1846

Emerg 2.533 150 2667 2631 2595 2557 2519 2480 2440 2399 2356 2313 2268 2221

Normal 0 160 2364 2329 2293 2257 2220 2183 2145 2106 2067 2027 1986 1943

Emerg 2.533 160 2736 2702 2667 2632 2596 2559 2521 2483 2443 2402 2360 2316

Normal 0 170 2435 2401 2367 2333 2298 2263 2227 2190 2153 2115 2076 2036

Emerg 2.533 170 2802 2770 2738 2704 2670 2635 2600 2563 2526 2487 2448 2407

Normal 0 180 2504 2472 2440 2407 2374 2340 2306 2271 2236 2200 2163 2125

Emerg 2.533 180 2868 2837 2806 2775 2742 2709 2675 2641 2605 2569 2532 2493

DAY - Steady State Thermal Rating (Ampacity), Amperes

1590 54/19 ACSR - Falcon Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2005 1959 1912 1864 1815 1765 1714 1660 1606 1549 1491 1430

Emerg 2.533 100 2382 2336 2288 2239 2188 2136 2081 2025 1966 1905 1841 1774

Normal 0 110 2086 2043 1999 1954 1908 1860 1812 1763 1712 1660 1606 1550

Emerg 2.533 110 2461 2418 2373 2327 2280 2231 2181 2129 2075 2019 1960 1900

Normal 0 120 2164 2123 2081 2038 1995 1951 1905 1859 1812 1763 1713 1661

Emerg 2.533 120 2536 2495 2454 2410 2366 2321 2274 2225 2176 2124 2070 2015

Normal 0 125 2202 2162 2121 2079 2037 1994 1950 1905 1859 1812 1764 1714

Emerg 2.533 125 2573 2533 2492 2451 2408 2364 2318 2272 2223 2174 2122 2069

Normal 0 130 2239 2200 2160 2120 2079 2037 1994 1950 1906 1860 1813 1765

Emerg 2.533 130 2608 2570 2530 2490 2448 2406 2362 2317 2270 2222 2172 2121

Normal 0 140 2311 2274 2236 2198 2159 2119 2079 2037 1995 1952 1908 1863

Emerg 2.533 140 2677 2641 2604 2566 2526 2486 2445 2403 2359 2314 2268 2220

Normal 0 150 2381 2345 2309 2273 2236 2198 2160 2121 2081 2041 1999 1957

Emerg 2.533 150 2744 2710 2675 2638 2601 2564 2525 2485 2444 2402 2359 2314

Normal 0 160 2449 2415 2381 2346 2311 2275 2239 2202 2164 2125 2086 2046

Emerg 2.533 160 2809 2777 2743 2709 2674 2638 2601 2564 2525 2486 2445 2403

Normal 0 170 2515 2483 2450 2417 2383 2349 2315 2279 2244 2207 2170 2132

Emerg 2.533 170 2873 2842 2810 2777 2744 2710 2675 2640 2603 2566 2528 2488

Normal 0 180 2581 2550 2518 2487 2454 2422 2389 2355 2321 2286 2251 2215

Emerg 2.533 180 2935 2905 2875 2844 2812 2780 2747 2713 2679 2643 2607 2570

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

Page 43: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 43 of 47 Revised: 03/01/10

1780 84/19 ACSR - Chukar Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2171 2121 2070 2018 1965 1911 1855 1798 1739 1678 1614 1549

Emerg 2.533 100 2570 2520 2468 2415 2360 2304 2245 2184 2121 2055 1986 1914

Normal 0 110 2263 2216 2168 2120 2070 2019 1966 1913 1858 1801 1743 1682

Emerg 2.533 110 2661 2614 2565 2516 2465 2412 2358 2301 2243 2183 2120 2054

Normal 0 120 2353 2308 2262 2216 2169 2121 2072 2022 1970 1917 1862 1806

Emerg 2.533 120 2747 2703 2658 2611 2564 2514 2464 2411 2357 2301 2243 2183

Normal 0 125 2396 2352 2308 2263 2217 2170 2123 2074 2024 1973 1920 1866

Emerg 2.533 125 2790 2747 2703 2657 2611 2563 2514 2464 2412 2358 2302 2244

Normal 0 130 2438 2396 2353 2309 2264 2219 2172 2125 2076 2027 1976 1923

Emerg 2.533 130 2831 2789 2746 2703 2658 2611 2564 2515 2465 2412 2359 2303

Normal 0 140 2522 2481 2440 2398 2356 2313 2269 2224 2178 2131 2083 2034

Emerg 2.533 140 2912 2872 2832 2790 2748 2704 2660 2614 2566 2518 2467 2416

Normal 0 150 2603 2564 2525 2485 2445 2404 2362 2319 2276 2231 2186 2140

Emerg 2.533 150 2990 2952 2914 2875 2835 2793 2751 2708 2663 2618 2571 2522

Normal 0 160 2681 2645 2607 2569 2531 2492 2452 2411 2370 2328 2285 2241

Emerg 2.533 160 3066 3030 2994 2957 2918 2879 2840 2799 2757 2714 2669 2624

Normal 0 170 2759 2723 2688 2651 2614 2577 2539 2501 2461 2421 2381 2339

Emerg 2.533 170 3140 3106 3072 3036 3000 2963 2925 2886 2847 2806 2764 2721

Normal 0 180 2835 2801 2766 2732 2696 2661 2624 2588 2550 2512 2473 2434

Emerg 2.533 180 3213 3181 3148 3114 3079 3044 3008 2971 2934 2895 2856 2815

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

1780 84/19 ACSR - Chukar Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2034 1981 1926 1871 1813 1754 1693 1630 1565 1497 1425 1350

Emerg 2.533 100 2455 2403 2349 2293 2235 2175 2113 2048 1981 1910 1836 1758

Normal 0 110 2136 2086 2035 1983 1930 1875 1819 1760 1700 1638 1574 1506

Emerg 2.533 110 2553 2504 2454 2402 2348 2293 2236 2176 2115 2051 1984 1913

Normal 0 120 2234 2187 2139 2090 2040 1988 1936 1882 1826 1769 1710 1649

Emerg 2.533 120 2646 2600 2553 2505 2455 2403 2350 2295 2239 2180 2118 2054

Normal 0 125 2281 2235 2188 2141 2092 2043 1992 1940 1886 1831 1774 1715

Emerg 2.533 125 2691 2647 2601 2554 2506 2456 2405 2352 2297 2241 2182 2121

Normal 0 130 2327 2282 2237 2191 2144 2096 2046 1996 1944 1891 1836 1780

Emerg 2.533 130 2736 2692 2648 2602 2556 2508 2458 2407 2354 2300 2243 2185

Normal 0 140 2417 2374 2331 2288 2243 2198 2152 2104 2056 2006 1955 1902

Emerg 2.533 140 2821 2780 2739 2696 2652 2607 2560 2512 2463 2413 2360 2306

Normal 0 150 2504 2463 2423 2381 2339 2296 2252 2208 2162 2115 2067 2018

Emerg 2.533 150 2904 2865 2826 2785 2744 2701 2658 2613 2567 2519 2470 2420

Normal 0 160 2588 2549 2511 2471 2431 2390 2349 2307 2264 2219 2174 2128

Emerg 2.533 160 2984 2948 2910 2872 2833 2792 2751 2709 2666 2621 2575 2528

Normal 0 170 2670 2633 2596 2559 2521 2482 2442 2402 2361 2320 2277 2234

Emerg 2.533 170 3063 3028 2992 2956 2918 2880 2841 2801 2761 2719 2675 2631

Normal 0 180 2750 2715 2680 2644 2607 2571 2533 2495 2456 2416 2376 2335

Emerg 2.533 180 3139 3106 3072 3037 3002 2966 2929 2891 2852 2812 2772 2730

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 44: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 44 of 47 Revised: 03/01/10

2167 72/7 ACSR - Kiwi Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2434 2378 2322 2264 2205 2144 2081 2017 1951 1883 1812 1738

Emerg 2.533 100 2858 2803 2746 2687 2626 2563 2498 2431 2361 2288 2211 2131

Normal 0 110 2540 2487 2434 2379 2323 2266 2208 2148 2086 2023 1957 1889

Emerg 2.533 110 2962 2910 2857 2802 2745 2687 2626 2564 2499 2432 2362 2289

Normal 0 120 2642 2592 2541 2490 2437 2383 2328 2272 2214 2154 2093 2031

Emerg 2.533 120 3062 3013 2962 2911 2858 2803 2747 2689 2628 2566 2502 2435

Normal 0 125 2692 2643 2593 2543 2492 2439 2386 2331 2275 2218 2159 2098

Emerg 2.533 125 3110 3062 3014 2963 2912 2859 2804 2748 2690 2630 2568 2504

Normal 0 130 2741 2693 2645 2596 2546 2495 2443 2390 2335 2279 2222 2164

Emerg 2.533 130 3157 3111 3064 3015 2965 2914 2861 2807 2750 2693 2633 2571

Normal 0 140 2836 2791 2745 2698 2651 2602 2553 2503 2451 2399 2345 2290

Emerg 2.533 140 3250 3206 3161 3115 3068 3020 2970 2919 2866 2812 2756 2699

Normal 0 150 2929 2886 2842 2797 2752 2706 2659 2612 2563 2513 2462 2410

Emerg 2.533 150 3340 3298 3256 3212 3168 3122 3075 3027 2977 2926 2874 2820

Normal 0 160 3020 2979 2937 2894 2851 2807 2763 2717 2671 2624 2576 2526

Emerg 2.533 160 3428 3388 3348 3306 3264 3221 3176 3131 3084 3036 2987 2936

Normal 0 170 3109 3069 3029 2989 2947 2905 2863 2820 2776 2731 2685 2638

Emerg 2.533 170 3514 3476 3437 3398 3358 3316 3274 3231 3187 3142 3095 3047

Normal 0 180 3197 3159 3120 3081 3042 3001 2961 2919 2877 2835 2791 2747

Emerg 2.533 180 3598 3562 3525 3487 3449 3410 3370 3329 3287 3244 3200 3154

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

2167 72/7 ACSR - Kiwi Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2279 2219 2158 2096 2032 1966 1897 1827 1753 1677 1597 1513

Emerg 2.533 100 2727 2669 2609 2547 2483 2416 2347 2275 2200 2122 2039 1952

Normal 0 110 2395 2340 2283 2224 2164 2103 2040 1975 1908 1838 1765 1690

Emerg 2.533 110 2839 2785 2729 2671 2612 2550 2487 2421 2352 2281 2206 2128

Normal 0 120 2507 2454 2400 2346 2290 2232 2173 2113 2051 1986 1920 1851

Emerg 2.533 120 2946 2895 2842 2789 2733 2676 2617 2556 2493 2427 2359 2288

Normal 0 125 2561 2510 2457 2404 2350 2294 2237 2179 2119 2057 1993 1927

Emerg 2.533 125 2997 2948 2897 2845 2791 2736 2679 2620 2559 2496 2431 2363

Normal 0 130 2614 2564 2513 2461 2409 2355 2299 2243 2185 2125 2064 2000

Emerg 2.533 130 3048 3000 2951 2900 2848 2795 2740 2683 2624 2563 2500 2435

Normal 0 140 2717 2669 2621 2572 2522 2472 2420 2366 2312 2256 2199 2140

Emerg 2.533 140 3146 3101 3055 3007 2958 2908 2856 2803 2748 2692 2633 2573

Normal 0 150 2816 2771 2726 2679 2632 2584 2535 2484 2433 2381 2327 2272

Emerg 2.533 150 3242 3199 3155 3110 3064 3016 2968 2918 2866 2814 2759 2703

Normal 0 160 2913 2870 2827 2783 2738 2692 2645 2598 2550 2500 2450 2398

Emerg 2.533 160 3334 3293 3252 3209 3165 3121 3075 3028 2979 2930 2879 2826

Normal 0 170 3008 2967 2925 2883 2840 2797 2753 2707 2662 2615 2567 2518

Emerg 2.533 170 3424 3385 3346 3305 3264 3222 3178 3134 3088 3041 2993 2944

Normal 0 180 3100 3061 3021 2981 2940 2899 2857 2814 2770 2726 2680 2634

Emerg 2.533 180 3513 3476 3438 3399 3360 3320 3278 3236 3193 3149 3104 3057

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 45: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 45 of 47 Revised: 03/01/10

2300 84/19 ACSR Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2571 2512 2453 2392 2329 2265 2199 2132 2062 1990 1915 1837

Emerg 2.533 100 3005 2946 2887 2825 2761 2695 2627 2556 2483 2406 2326 2242

Normal 0 110 2682 2627 2570 2513 2454 2394 2332 2269 2204 2137 2068 1996

Emerg 2.533 110 3113 3059 3003 2945 2886 2824 2761 2696 2628 2557 2484 2407

Normal 0 120 2789 2737 2683 2629 2573 2517 2459 2399 2338 2276 2211 2145

Emerg 2.533 120 3217 3166 3113 3059 3004 2946 2887 2826 2763 2698 2630 2560

Normal 0 125 2842 2790 2738 2685 2631 2576 2519 2462 2403 2342 2280 2216

Emerg 2.533 125 3268 3218 3167 3114 3060 3005 2948 2889 2828 2765 2700 2633

Normal 0 130 2893 2843 2792 2740 2688 2634 2579 2523 2466 2407 2347 2285

Emerg 2.533 130 3318 3269 3219 3168 3116 3062 3007 2950 2891 2830 2768 2703

Normal 0 140 2993 2946 2897 2848 2798 2747 2695 2642 2588 2533 2476 2418

Emerg 2.533 140 3415 3369 3322 3273 3224 3173 3121 3068 3013 2956 2897 2837

Normal 0 150 3091 3045 2999 2952 2905 2856 2807 2757 2705 2653 2600 2545

Emerg 2.533 150 3509 3465 3420 3375 3328 3280 3231 3181 3129 3076 3021 2964

Normal 0 160 3186 3143 3099 3054 3008 2962 2915 2867 2819 2769 2718 2667

Emerg 2.533 160 3601 3559 3517 3473 3429 3384 3337 3289 3240 3190 3139 3085

Normal 0 170 3280 3238 3196 3153 3109 3065 3021 2975 2929 2882 2833 2784

Emerg 2.533 170 3690 3651 3610 3569 3527 3484 3440 3395 3348 3301 3252 3202

Normal 0 180 3371 3331 3291 3250 3208 3166 3123 3080 3036 2991 2945 2898

Emerg 2.533 180 3778 3741 3702 3663 3623 3582 3540 3497 3453 3408 3362 3315

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

2300 84/19 ACSR Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2405 2343 2279 2213 2145 2075 2003 1929 1851 1771 1686 1598

Emerg 2.533 100 2864 2803 2740 2675 2608 2538 2466 2390 2311 2228 2142 2050

Normal 0 110 2528 2470 2409 2348 2285 2220 2153 2085 2014 1940 1864 1784

Emerg 2.533 110 2982 2925 2866 2806 2743 2679 2612 2543 2470 2395 2317 2235

Normal 0 120 2646 2590 2533 2476 2417 2356 2294 2230 2165 2097 2027 1954

Emerg 2.533 120 3094 3040 2985 2929 2870 2810 2749 2684 2618 2549 2477 2403

Normal 0 125 2702 2648 2593 2537 2480 2421 2361 2300 2236 2171 2104 2034

Emerg 2.533 125 3148 3096 3043 2988 2932 2874 2814 2752 2688 2622 2553 2482

Normal 0 130 2758 2705 2652 2597 2542 2485 2427 2367 2306 2243 2178 2112

Emerg 2.533 130 3201 3150 3099 3046 2991 2935 2877 2818 2756 2692 2626 2558

Normal 0 140 2866 2816 2766 2714 2662 2608 2553 2497 2440 2381 2321 2259

Emerg 2.533 140 3304 3256 3208 3158 3106 3054 3000 2944 2886 2827 2766 2702

Normal 0 150 2971 2924 2875 2826 2777 2726 2674 2622 2568 2512 2456 2398

Emerg 2.533 150 3404 3359 3313 3265 3217 3167 3117 3064 3010 2955 2898 2839

Normal 0 160 3073 3028 2982 2935 2888 2840 2791 2741 2690 2638 2585 2530

Emerg 2.533 160 3501 3458 3414 3369 3324 3277 3229 3180 3129 3077 3023 2968

Normal 0 170 3172 3129 3085 3041 2996 2950 2903 2856 2808 2759 2708 2657

Emerg 2.533 170 3595 3554 3513 3471 3427 3383 3337 3291 3243 3194 3144 3092

Normal 0 180 3269 3228 3186 3144 3101 3057 3013 2968 2922 2875 2827 2779

Emerg 2.533 180 3687 3649 3609 3569 3528 3486 3443 3398 3353 3307 3259 3210

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 46: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 46 of 47 Revised: 03/01/10

2493 54/37 ACAR Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2572 2513 2453 2392 2330 2266 2200 2132 2062 1990 1916 1838

Emerg 2.533 100 3006 2947 2888 2826 2762 2696 2628 2557 2484 2407 2327 2242

Normal 0 110 2687 2631 2575 2517 2458 2398 2336 2273 2208 2141 2071 2000

Emerg 2.533 110 3118 3064 3008 2950 2890 2829 2766 2700 2632 2561 2488 2411

Normal 0 120 2797 2745 2691 2636 2581 2524 2466 2406 2345 2282 2218 2151

Emerg 2.533 120 3227 3175 3122 3068 3012 2955 2895 2834 2771 2706 2638 2568

Normal 0 125 2851 2800 2748 2694 2640 2585 2528 2470 2411 2350 2288 2224

Emerg 2.533 125 3279 3229 3178 3125 3071 3015 2958 2899 2838 2775 2709 2642

Normal 0 130 2905 2854 2803 2751 2699 2645 2590 2533 2476 2417 2356 2294

Emerg 2.533 130 3331 3282 3232 3181 3129 3075 3019 2962 2903 2842 2779 2714

Normal 0 140 3009 2961 2912 2863 2812 2761 2709 2656 2601 2546 2489 2430

Emerg 2.533 140 3432 3386 3339 3290 3241 3190 3137 3084 3028 2971 2912 2851

Normal 0 150 3110 3064 3018 2971 2923 2874 2824 2774 2722 2670 2616 2561

Emerg 2.533 150 3531 3487 3442 3396 3349 3301 3251 3201 3148 3095 3039 2983

Normal 0 160 3209 3166 3121 3076 3030 2984 2936 2888 2839 2789 2738 2686

Emerg 2.533 160 3627 3585 3542 3499 3454 3408 3361 3313 3264 3213 3161 3108

Normal 0 170 3307 3265 3222 3179 3135 3091 3046 3000 2953 2905 2857 2807

Emerg 2.533 170 3721 3681 3640 3599 3556 3513 3468 3423 3376 3328 3279 3229

Normal 0 180 3403 3362 3321 3280 3238 3195 3152 3108 3064 3018 2972 2925

Emerg 2.533 180 3813 3775 3736 3697 3656 3615 3572 3529 3485 3439 3393 3345

NIGHT - Steady State Thermal Rating (Ampacity), Amperes

2493 54/37 ACAR Planning Rating Winter Planning Rating Summer

Rating Condition

Wind

Speed

(ft/sec)

Condr

Max

Temp

Deg C -15 -10 -5 0 5 10 15 20 25 30 35 40

Normal 0 100 2406 2344 2279 2213 2146 2076 2004 1929 1852 1771 1687 1598

Emerg 2.533 100 2865 2804 2741 2676 2609 2539 2466 2391 2312 2229 2142 2051

Normal 0 110 2533 2474 2413 2352 2289 2224 2157 2088 2017 1944 1867 1787

Emerg 2.533 110 2987 2930 2871 2810 2748 2683 2616 2547 2474 2399 2321 2238

Normal 0 120 2653 2597 2541 2483 2424 2363 2301 2237 2171 2103 2033 1960

Emerg 2.533 120 3102 3049 2994 2937 2879 2819 2756 2692 2626 2556 2485 2410

Normal 0 125 2712 2658 2602 2546 2489 2430 2370 2308 2244 2179 2111 2041

Emerg 2.533 125 3159 3107 3053 2998 2942 2884 2824 2762 2697 2631 2562 2490

Normal 0 130 2769 2716 2663 2608 2552 2495 2437 2377 2315 2252 2187 2120

Emerg 2.533 130 3214 3163 3111 3058 3003 2947 2889 2829 2767 2703 2637 2568

Normal 0 140 2881 2831 2780 2728 2675 2621 2566 2510 2453 2394 2333 2270

Emerg 2.533 140 3321 3273 3224 3174 3123 3070 3015 2959 2901 2842 2780 2716

Normal 0 150 2990 2942 2893 2844 2794 2743 2691 2638 2584 2528 2471 2413

Emerg 2.533 150 3425 3380 3333 3286 3237 3187 3136 3083 3029 2973 2916 2857

Normal 0 160 3095 3050 3003 2957 2909 2860 2811 2761 2710 2657 2603 2548

Emerg 2.533 160 3526 3483 3439 3394 3348 3301 3252 3203 3152 3099 3045 2990

Normal 0 170 3198 3155 3111 3066 3021 2974 2927 2880 2831 2781 2731 2679

Emerg 2.533 170 3625 3584 3542 3499 3456 3411 3365 3318 3270 3220 3170 3117

Normal 0 180 3299 3258 3215 3173 3129 3085 3041 2995 2949 2902 2854 2804

Emerg 2.533 180 3721 3682 3643 3602 3560 3518 3474 3430 3384 3337 3289 3240

DAY - Steady State Thermal Rating (Ampacity), Amperes

Page 47: VI.A BARE OVERHEAD TRANSMISSION CONDUCTOR RATINGS

Originally Issued: 10/09

DMS #590159 Page 47 of 47 Revised: 03/01/10

References T72 189-4 “Effect of Elevated Temperature on the Strength of Aluminum Conductors” by J. R. Harvey IEEE Paper C72 188-6 “Effect of Elevated Temperature on the “Performance of Conductor Accessories” by W. B. Howett and T. E. Simpkins Southwire “Overhead Conductor Manual,”2007 IEEE Std. 738-2006“IEEE Standard for Calculating the Current - Temperature Relationship of Bare Overhead Conductors" PJM Circuit Rating Review, C&TPS Report to P&E Committee, May 1986