EDS 01-0045 Overhead Line Ratings · PDF fileEDS 01-0045 OVERHEAD LINE RATINGS ... Table A1- Aluminium Conductor Steel Reinforced (ACSR), ... provided data on the likelihood of a conductor

Document Number: EDS 01-0045

Version: 3.0

Date: 21/06/2016

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ENGINEERING DESIGN STANDARD

EDS 01-0045

OVERHEAD LINE RATINGS

Network(s): EPN, LPN, SPN

Summary: This standard details the Electricity Networks Association (ENA) Engineering Recommendation P27 Current Rating Guide for UK Power Networks Overhead Lines.

Author: Alan Archer Date: 21/06/2016

Approved By: Paul Williams Approved Date: 28/06/2016

This document forms part of the Company’s Integrated Business System and its requirements are mandatory throughout UK Power Networks. Departure from these requirements may only be taken with the written approval of the Director of Asset Management. If you have any queries about this document please contact the author or owner of the current issue.

Applicable To

UK Power Networks External

All UK Power Networks G81 Website

Asset Management Contractors

Capital Programme ICPs/IDNOs

Connections Meter Operators

HSS&TT

Network Operations

UK Power Networks Services

Other

Overhead Line Ratings Document Number: EDS 01-0045

Version: 3.0

Date: 21/06/2016

© UK Power Networks 2016 All rights reserved 2 of 12

Revision Record

Version 3.0 Review Date 28/06/2019

Date 21/06/2016 Author Alan Archer

Why has the document been updated – Periodic review of document and supporting document EDS 01-0045b

What has changed – ENA ER P27 title clarified in Introduction, department updated in Section 7.

Document transferred onto a new template and rules applied.

Version 13/05/2013 Review Date 30/04/2016

Date 2.0 Author Florence Nanyonjo

Appendix A - amended to include ratings for conductor sizes and types used on the LV network and a section of all conductor post – fault ratings.

Version 1.2 Review Date

Date 23/07/2012 Author Lee Strachan

Document reviewed for publishing on G81 website


Date 02/08/2011 Author Chris Anderson

Reclassified from EI to EDS


Date 29/12/2010 Author Martin Payne

Original. NBC_11_0018.


Version: 3.0

Date: 21/06/2016


Contents

1 Introduction ............................................................................................................. 4

2 Scope ....................................................................................................................... 4

3 Methodology of Conductor Ratings ....................................................................... 4

4 Circuit Identification ................................................................................................ 4

5 Ratings ..................................................................................................................... 5

6 Applying Appropriate Levels of Exceedance ........................................................ 5

7 Calculating of Conductor Ratings .......................................................................... 5

8 References ............................................................................................................... 6

9 Dependent Documents............................................................................................ 6

Appendix A – Pre-fault and Post-fault Conductor Current Ratings at 500c Operating Temperature ............................................................................................................. 7

Table A1- Aluminium Conductor Steel Reinforced (ACSR), All Aluminium Alloy Conductor (AAAC) and Hard Drawn Aluminium (HDAL) ...................................... 7

Table A2- Hard drawn (HD) Copper and Cadmium (CAD) Copper ................................... 9

Table A3- Covered Core Conductor (CCC) or BLX and Aerial Bundled Conductor (ABC) ...................................................................................................................... 12


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1 Introduction

This standard details the Electricity Networks Association (ENA) Engineering Recommendation P27 ‘Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System’.

2 Scope

This standard specifies the use of the cable rating tool ‘ORAT 4’ (developed by EA Technology as part of the Overhead Line Strategic Technology Project), which specifies the current ratings that UK Power Networks’ overhead line network should be designed and operated to.

3 Methodology of Conductor Ratings

The ratings contained in ER P27 are based on statistical studies by CERL. These studies provided data on the likelihood of a conductor exceeding its maximum operating temperature for a given continuous current in specified weather conditions. The aggregate period of time during which the conductor exceeds its maximum operating temperature is called the 'exceedance'. It is usually expressed as the percentage of the total time for which the current was maintained. ER P27 makes no distinction between pre-fault and post-fault ratings and allows 0.001% excursion time for single circuits and 3% for double circuits. Under post-fault conditions the duration of the excursion is not set out as in ER P27. Under these conditions and dependant on the network configurations, the percentage exceedance can be altered. Table 1 gives guidance on this. All ratings are appropriate to their maximum operating temperature and the season (winter, spring/autumn, summer), for which an ambient temperature is specified.

4 Circuit Identification

Under ER P27 there is the need to identify the type of circuit you are operating. These types of circuit are identified as:

Single Circuit. Single circuit radial systems. eg. LV and 11kV spur.

Secondary Distribution. These refer to ring-type systems with a number of tapping off points, such as 11kV main lines.

Multi-circuit Primary. These refer to circuits which would be called upon to supply maximum load only in the event of the outage of another circuit, the category therefore includes 132kV and 33kV duplicate transformer feeders, together with some untapped 11kV circuits providing a firm supply to end loads.


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5 Ratings

Two different ratings criteria will be applied to an overhead line:

Pre-fault Rating. This is the maximum continuous rating appropriate to the season which may be applied without time limitation.

Post-fault Rating. This is the maximum continuous rating appropriate to the season which may be applied in a fault situation until pre-fault requirements can be restored. Normally this would be for a period well within 24 hours.

6 Applying Appropriate Levels of Exceedance

Table 1 gives guidance on the exceedance levels that should be applied to the different types of circuit configurations. It is split into two categories:

Pre-fault. Normal operating conditions that apply to the methodology of ENA P27.

Post-fault. Due to the nature of the circuit configuration and the duration of the running arrangement the exceedance levels have been altered from those set out in ENA P27.

Type of Circuit Load Shape Pre-fault Exceedance Value

Post-fault Exceedance Value

Single Circuit Rating Not Dependant on Load Shape

0.001% 0.001%

Secondary Distribution 0.001% 3%

Multi-circuit Primary

General Distribution 3% 10%

Intensive Industrial or City Centre

3% for loads at

0.96 x Rating 10%

Table 1 – Levels of Exceedance

7 Calculating of Conductor Ratings

The most commonly used conductor ratings have been included in Appendix A of this document.

If additional ratings are required, these will be calculated by the UK Power Networks Technical Sourcing and Standards team within Asset Management, using the EA Technology OHRAT Calculation of Distribution Ratings for Overhead Conductors software.


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8 References

ENA ER P27 Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System

9 Dependent Documents

The following documents are referenced in this document, any of which may be affected by updates.

EDS 01-0045b OHRAT Calculation of Distribution Ratings for Overhead Conductors

EDS 08-0109 11/6.6kV Secondary Distribution Network Design

EOS 09-0070 Dynamic Line Rating (DLR) Monitoring Equipment on 33kV Distribution Lines

Overhead Line Craft Manual Section 6


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Appendix A – Pre-fault and Post-fault Conductor Current Ratings at 500c Operating Temperature

Table A1- Aluminium Conductor Steel Reinforced (ACSR), All Aluminium Alloy Conductor (AAAC) and Hard Drawn Aluminium (HDAL)

PRE- FAULT RATING POST- FAULT RATING

Conductor Size and Type Exceedance Level

Summer Rating (A)

Spring/Autumn Rating (A)

Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

Gopher 25mm2

ACSR

0.001%

100 116 125

0.001%

100 116 125

Rabbit 50mm² ACSR 158 184 198 158 184 198

Horse 70mm2

ACSR 206 238 258 206 238 258

Dog 100mm² ASCR 252 289 310 252 289 310

Wolf 150mm² ACSR

0.001% 346 401 431 3% 392 454 488

3% 392 454 488 10% 415 481 517

Lynx 175mm² ACSR

0.001% 382 442 476 3% 432 501 539

3% 432 501 539 10% 458 531 571

Jaguar 200mm² ASCR

0.001% 407 472 507 3% 416 534 575

3% 416 534 575 10% 489 566 609


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Summer Rating (A)


Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

Zebra 400mm² ACSR

0.001% 658 760 817 3% 745 861 925

3% 745 861 925 10% 790 913 981

Hazel 50mm² AAAC

0.001%

165 191 206

0.001%

165 191 206

Oak 100mm² AAAC 259 301 324 259 301 324

Ash 150mm² AAAC

0.001% 343 398 428 3% 389 450 485

3% 389 450 485 10% 412 477 514

Poplar 200mm² AAAC

0.001% 413 479 515 3% 468 542 584

3% 468 542 584 10% 497 575 619

Upas 300mm² AAAC

0.001% 546 632 679 3% 618 715 769

3% 618 715 769 10% 655 759 816

Ant 50mm2

HDAL

0.001%

163 189 204

0.001%

163 189 204

Wasp 100mm2 HDAL 258 299 322 258 299 322


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Table A2- Hard drawn (HD) Copper and Cadmium (CAD) Copper



Summer Rating (A)


Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

0.025 Copper 0.025in² HDC

0.001%

99 114 123

0.001%

99 114 123

0.05 Copper 0.05in² HDC 155 180 194 155 180 194

0.1 Copper 0.1in² HDC 237 275 296 237 275 296


0.001% 309 358 385 3% 350 405 437

3% 350 405 437 10% 379 440 474


0.001% 375 435 465 3% 425 490 530

3% 425 490 530 10% 437 507 545

16 Metric Copper

16mm2 HDC

0.001%

99 115 124

0.001%

99 115 124

25 Metric Copper

25mm2

HDC 126 147 158

126 147 158

32 Metric Copper

32mm2 HDC 155 180 194

155 180 194


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Summer Rating (A)


Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

16 Metric Copper

16mm2 HDC

0.001%

99 115 124

0.001%

99 115 124

25 Metric Copper

25mm2

HDC 126 147 158 126 147 158

32 Metric Copper

32mm2 HDC 155 180 194 155 180 194

35 Metric Copper

35mm2

HDC 156 181 195 156 181 195

70 Metric Copper

70mm2 HDC 245 285 307 245 285 307

100 Metric Copper

100mm2 HDC

0.001% 316 367 395 3% 358 415 447

3% 358 415 447 10% 379 440 474

125 Metric Copper

125mm2 HDC

0.001% 364 422 454 3% 412 478 515

3% 412 478 515 10% 437 507 545

0.17 CAD Copper

0.17in² CADC 0.001% 78 90 97

0.001% 78 90 97


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Summer Rating (A)


Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

0.025 CAD Copper

0.025in² CADC

0.001%

96 111 120

0.001%

96 111 120

0.035 CAD Copper

0.035in² CADC 121 141 152 121 141 152

0.04 CAD Copper

0.04in² CADC 131 152 164 131 152 164

0.05 CAD Copper

0.05in² CADC 150 174 188 150 174 188

0.075 CAD Copper

0.075in² CADC 197 229 247 197 229 247

0.1 CAD Copper

0.1in² CADC 237 275 296 237 275 296

0.15 CAD Copper

0.15in² CADC

0.001% 312 362 389 3% 353 410 441

3% 353 410 441 10% 375 434 468

0.175 CAD Copper

0.175in² CADC

0.001% 347 402 433 3% 393 456 490

3% 393 456 490 10% 417 483 520


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Table A3- Covered Core Conductor (CCC) or BLX and Aerial Bundled Conductor (ABC)



Summer Rating (A)


Winter Rating (A)

Exceedance Level

Summer Rating (A)


Winter Rating (A)

50 BLX 50mm² CCC

0.001%

148 172 185

0.001%

148 172 185

120 BLX 120mm² CCC 264 306 329 264 306 329

185 BLX 185mm² CCC

0.001% 346 401 431 3% 392 454 489

3% 392 454 489 10% 416 481 518

35 ABC 35mm2 ABC

0.001%

105 115 124

0.001%

105 115 124

50 ABC 50mm2 ABC 143 157 163 143 157 163

95 ABC 95mm2 ABC 228 250 260 228 250 260

120 ABC 120mm2 ABC 277 304 327 277 304 327