Fuse Curves

May 2001

CAT.71.01.T.E

Cutler-Hammer

B4-1Medium-Voltage Distribution EquipmentPower and Distribution Class Fuses

General Description

Cutler-Hammer Medium-Voltage Fuse Family

Current Limiting Expulsion

HLE: Helical Configuration Current Limiting, E-rated

CLE: Current Limiting, E-ratedAcid

CLS: Current Limiting Starter (motor starter)

CLT: Current Limiting Transformer

CX: Current Limiting, X asin McGraw Edison’s NX

RBA: Refillable, Boric Acid

RDB: Refillable, Dropout, Boric Acid

DBU: Drop-out, Boric Acid, U as in S&C’s SMU

DBA: Drop-out, Boric Acid

BA: Boric Acid

form to ANSI specifications. Some motor starter fuses are UR recog-nized and both current limiting and expulsion fuses have been approved in UL rated switchgear.

Current limiting and expulsion fuses can be used to meet any overcur-rent protection need. At any point along the electrical distribution sys-tem, Cutler-Hammer has a fuse to satisfy your overcurrent protection needs.

Medium-Voltage Fuses

Cutler-Hammer is the only North American manufacturer of both cur-rent limiting and expulsion medium-voltage power fuses. A full range of general purpose, backup and boric acid fuses is available for distribu-tion and power applications.

All Cutler-Hammer medium-voltage fuses are thoroughly tested and con-

Application Guide

Type Fuse Voltage Range Fuse Ampere Rating Fuse Max Interrupting Rating(kA Sym)

Class Use Indoor/Outdoor

Applied in:

Current Limiting

CLE/HLE

2.4 kV – 15.5 kV 10E – 1350A 85 kA General PurposePower Indoor/Outdoor

Fused switches, feeder circuit sectionalizing, power transformers, dip poles, substation capacitor banks.

CLPT/NCLPT

2.4 kV – 38 kV 0.25E – 10E 80 kA General PurposeIndoor

Potential transformers. BAL-1 mountings and clips are no longer available.

CLSLCLS

2.4 kV – 8.3 kV 2R – 44R 50 kA Backup DistributionIndoor

AMPGARD and non-AMPGARD Motor starters. HCLS version is the same as the CLS except hermetically sealed for hazardous locations.

CX/CXN

4.3 kV – 15.5 kV 3.5C – 300C 50 kA General Purpose Distribution Indoor

Padmounted distribution transformers, Substation service transformers, and fused switches. Direct substitution for McGraw’s NX fuse.

CLT 2.4 kV – 15.5 kV 4A – 150A 25 kA General Purpose Distribution Indoor

Padmounted distribution transformers.

Expulsion Fuses

RBA 2.4 kV – 38 kV 0.5E – 720E 37.5 kA Boric Acid PowerIndoor

Fused switches, feeder circuit sectionalizing, and power transformers

RDB 2.4 kV – 38 kV 0.5E – 720E 37.5 kA Boric Acid PowerOutdoor

Feeder circuit sectionalizing, power transformers, substation service transformers, dip poles, potential transformers, and substation capacitor banks. Outdoor version of the RBA.

DBU 4.4 kV – 38 kV 15E – 200E 50 kA Boric Acid PowerIndoor/Outdoor

Feeder circuit sectionalizing, fused switches, power transformers, substation service transformers, dip poles, and potential transformers. Direct substitute for S&C’s SMU-20 refills.

DBA 7.2 kV – 138 kV 0.5A – 200E 12.5 kA Boric Acid PowerOutdoor

Only DBA-1 and DBA-2 fuse units are available. DBA-5 fuses superseded by DBA-2. DBA hardware no longer available.

BA 4.8 kV – 15.5 kV 0.5A – 720E – Boric Acid PowerIndoor/Outdoor

Replaced by the RBA/RDB fuse line. Only refills, filters and condensers are available.

CAT.71.01.T.E

Cutler-Hammer

B4-2

May 2001

Interrupting Current

Cu

rren

t Li

mit

ing

Typ

e

i max. – maximum ratedinterrupting current

i min. – minimum ratedinterrupting current

i hr. – current causing elementmelting in 1 hour

i – any current meltingelement with no timelimit Backup

General Purpose

i i hr. i min. i max.

Full Range

Medium-Voltage Distribution EquipmentPower and Distribution Class Fuses

General Description

Figure 1. General Fuse Comparison

Expulsion Current Limiting

Vented

Electromechanical

Interrupts at Current Zero

Generally Higher Voltage and Current Application Capabilities

Different Time/CurrentCharacteristics

Sealed

Static

Limits Fault Current

Generally Higher Interrupting Ratings

Different Time/Current Characteristics

The following fuse terminology will assist in understanding and select-ing the correct fuse. The following is a brief overview of those terms.

Power vs. Distribution

The differentiation is intended to indicate the test conditions and where fuses are normally applied in a power system, based on specific requirements for generating sources, substations and distribu-tion lines. Each class has its own unique set of voltage, current and construction requirements (see ANSI C37.42, .44, .46 and .47).

Low- vs. Medium- vs. High-Voltage

While fuses are defined in the ANSI standards as either low or high voltage, Cutler-Hammer has elected to name their fuses to correspond with the equipment in which they are installed. Therefore, per ANSI C84, fuses are named as follows:

Low-Voltage

1000V and below

Medium-Voltage

Greater than 1000V to 69,000

High-Voltage

Greater than69,000V

Expulsion vs. Current Limiting

Definitions per ANSI C47.40

Expulsion Fuses:

An expulsion fuse is a vented fuse in which the expul-sion effect of the gases produced by internal arcing, either alone or aided by other mechanisms, results in cur-rent interruption.

An expulsion fuse is not current limiting and as a result limits the duration of a fault on the electrical system, not the magnitude.

Current-Limiting Fuse:

A current lim-iting fuse is a fuse that, when its cur-rent responsive element is melted by a current within the fuse’s speci-fied current limiting range, abruptly introduces a high resistance to reduce current magnitude and dura-tion, resulting in subsequent current interruption.

Feature Comparison (Figure 1)

Fuse Types

There are three current-limiting fuse types: Backup, General Purpose and Full Range. It is important that the user have an understanding of these definitions to insure proper applica-tion of the fuse. (

Figure 2

)

Backup Fuse:

A fuse capable of interrupting all currents from the maximum rated interrupting cur-rent down to the rated minimum interrupting current.

Backup fuses are normally used for protection of motor starters and are always used in series with another interrupting device capable of inter-rupting currents below the fuses minimum interrupting current.

General Purpose Fuses:

A fuse capa-ble of interrupting all currents from the rated interrupting current down to the current that causes melting of the fusible element in no less than one hour.

General Purpose fuses are typically used to protect feeders and compo-nents such as transformers.

Full Range Fuses:

A fuse capable of interrupting all currents from the rated interrupting rating down to the minimum continuous current that causes melting of the fusible ele-ment, with the fuse applied at the maximum ambient temperature specified by the manufacturer.

Figure 2. Current Limiting Types Protection Range

May 2001

CAT.71.01.T.E

Cutler-Hammer


General Description

Current Limiting Fuses

HLE/CLECurrent Limiting – E-Rated

CLPT/NCLPTCurrent Limiting E-Rated for PotentialTransformer Protection

CXCurrent Limiting – Cross References with Cooper Power System’s NX Type

CLTCurrent Limiting for Transformer Protection

Current limiting fuses are con-structed with pure silver fuse ele-ments, high purity silica sand filler, and a glass resin outer casing.

A high fault current melts the silver element almost instantly and loses energy to the surrounding sand. The sand melts and forms fulgurite, a glass-like substance.The arc voltage rapidly increases to nearly three times the fuse voltage rating and forces the current to zero.

Low fault current melts a solder drop on the silver fuse element which, in turn, melts the silver. The element burns back until there is a sufficient internal gap to interrupt the current. This is known as the M-effect.

Cutler-Hammer offers current limit-ing fuses in two basic types: backup and general purpose. Backup fuses are applied in series with an expul-sion fuse to interrupt high fault cur-rents beyond the expulsion fuse’s range. General purpose fuses are designed to interrupt low fault cur-rents that cause it to melt in one (1) hour or less.

CLSCurrent Limiting for Motor Starter Protection

Accessories

A wide assortment of mountings, live parts and end fittings are available to facilitate power fuse installation.

Mountings

include a base, porcelain or glass polyester insulators, and live parts. They help enable the fuse to be safely attached to the gear. Mountings can be either disconnect or nondisconnect.

Live Parts

attach the fuse to the mountings and are considered part of the mounting. All parts above the insulators are live parts.

End Fittings

are metal parts that attach to each end of the fuse at the ferrules. They are used only on dis-connect fuses or when converting a nondisconnect to a disconnect fuse.

End Fittings

CAT.71.01.T.E

Cutler-Hammer

B4-4

May 2001


General Description

RBA – E-Rated Refillable Boric Acid

Cutler-Hammer expulsion fuses use boric acid as the interrupting medium. Under a fault condition, arc heat decomposes the boric acid into water vapor. The water vapor blast deionizes the arc path preventing arc reignition after a natural current zero.

Type RBA indoor expulsion fuses can be fitted with a discharge filter (muffler) or condenser, that moder-ates the discharge exhaust. The dis-charge filter limits the exhaust to a small and relatively inert amount of gas and lowers the noise level with-out affecting the fuse interrupting rating. Steam discharge, that can effect the interrupting, is fully restricted by the condenser.

Expulsion Fuses

RDB – E-Rated Refillable Dropout Boric Acid

Type RDB outdoor dropout fuses include an ejector spring which forces the arcing rod through the top of the fuse. The arcing rod strikes a latch on the mounting which forces the fuse to swing out-ward through a 180° arc into the dropout position.

Refill units can be field installed into RBA and RDB expulsion fuses. Once the old unit has been removed, the separately purchased unit can be easily installed into the fuse holder.

DBU – Dropout Boric Acid –Cross References with/S & C’s SMU – 20

Type DBU fuse units are designed to directly replace S&C type SMU-20 fuse refills in the aftermarket. Hard-ware is not available. (S&C end fit-tings shown here.)

Accessories

The following accessories are avail-able for expulsion fuses:

Mountings

include a base, porcelain or glass polyester insulators, and live parts. They help enable the fuse to be safely attached to the gear. Mountings can be either disconnect, nondisconnect or dropout. Fuses may be vertical or underhung.

Live Parts

attach the fuse to the mountings and are considered part of the mounting. All parts above the insulators are live parts.

Filters and Condensers

are for indoor applications of RBA expul-sion fuses. They confine the arc within the fuse and substantially reduce the noise and exhaust when the fuse interrupts.

May 2001

CAT.71.01.T.E

Cutler-Hammer


Technical Ratings

Table 1: Transformer Primary Fuse Application

SystemVoltage

FuseType

Maximum Transformer kVA

➀

Fuse Family/Characteristics

Self-Cooled Forced Air Type Current Range Maximum kV Amp Sym. Int. Rating

➁

2400 Current Limiting

371 742133622284010 742 890

433 866156026004676 8661039

CLECLECLECLE-750CLE-750CXNCXN

10-125150-250300-450600-750

1000-135060-250

300

5.5 50,00063,00063,00040,00040,00050,00050,0008.3

Expulsion 60011902140

69513852500

RBA-200RBA-400RBA-800

10-2005-4009-720

8.3 19,00037,50037,500


643128723173862695212861545

751150227034506811115011802


10-125150-250300-450600-750

1000-135060-250

300

5.5 50,00063,00063,00040,00031,50050,00050,0008.3


120024004320


10-2005-4009-720

8.3 19,00037,50037,500


742148326714451801314831780

865173131165193934817312077


10-125150-250300-450600-750

1000-135060-250

300

5.5 50,00063,00063,00040,00031,50050,00050,0008.3


138527755000


10-2005-4009-720

8.3 19,00037,50037,500


213 8531536298721342560

248 9951792348524902987

CLECLECLECLECXNCXN

10-2530-100

125-180200-35060-250

300

8.3 50,00050,00050,00050,00050,00050,000


200039857170


10-2005-4009-720

8.3 19,00037,50037,500


222 8901603311722262672

25910391870363725983117

CLECLECLECLECXNCXN

10-2530-100

125-180200-35060-250

300

8.3 50,00050,00050,00050,00050,00050,000


208041607500


10-2005-4009-720

8.3 19,00037,50037,500

➀

Maximum transformer kVA ratings are based on ratios of maximum fuse current rating to transformer full load current (I

F

/I

T

) as listed. For a 55°C rise liquid-filled trans-former, use the kVA rating for 65°C rise (55°C rating x 1.12). For suggested minimum fuse applications, see tables, page C4-7.

➁

The type RBA interrupting ratings shown are those of the discharge filter type, in which the noise is minimized and deionization of expulsion gases is assured.

These applications are subject to modification when specific factors such as transformer characterictics, other protective devices, coordina-tion requirements and load varia-tions may indicate a different I

F

/I

T

ratio.

Caution:

Primary fuses must not be relied upon for clearing secondary ground faults.

CAT.71.01.T.E

Cutler-Hammer

B4-6

May 2001


Technical Ratings

Table 1: Transformer Primary Fuse Application,

Continued

SystemVoltage

FuseType

Maximum Transformer kVA

➀

Fuse Family/Characteristics

Self-Cooled Forced Air Type Current Range Maximum kV Amp Sym. Int. Rating

➁

12,000 CurrentLimiting

371 1484 2226 4452 1484 2597

432 1731 2597 5195 1731 3030

CLECLECLECLECXNCXN

10-2530-100

125-180200-35045-100

120-175

15.5 31,50085,00050,00050,00050,00050,000

Expulsion 2970 5945

3465 6930

RBA-200RBA-400

10-2005-400

15.5 14,40029,400


408 1632 2449 4898 1632 2857

476 1905 2857 5715 1905 3333

CLECLECLECLECXNCXN

10-2530-100

125-180200-35045-100

120-175

15.5 31,50085,00050,00050,00050,00050,000

Expulsion 3265 6530

3810 7620

RBA-200RBA-400

10-2005-400

15.5 14,40029,400


426 1707 2560 5121 1707 5855

497 1991 2987 5975 1991 3485

CLECLECLECLECXNCXN

10-2530-100

125-180200-35045-100

120-175

15.5 31,50085,00050,00050,00050,00050,000

Expulsion 3415 6830

3985 7970

RBA-200RBA-400

10-2005-400

15.5 14,40029,400

23,000 Expulsion 5690 8535

6635 9950

RBA-200RBA-400

10-2005-300

25.5 10,50021,000

34,500 Expulsion 853512800

995014925

RBA-200RBA-400

10-2005-300

38 6,90016,800

➀

Maximum transformer kVA ratings are based on ratios of maximum fuse current rating to transformer full load current (IF/IT) as listed at right. For a 55°C rise liquid-filled transformer, use the kVA rating for 65°C rise (55°C rating x 1.12). For suggested minimum fuse applications, see tables, page C4-7.

These applications are subject to modification when specific factors such as transformer characterictics, other protective devices, coordina-tion requirements and load varia-tions may indicate a different I

F

/I

T

ratio.

Caution:

Primary fuses must not be relied upon for clearing secondary ground faults.

Selection of Minimum Primary Fuse for Transformer Protection

Instructions

: Multiply the transformer primary full load current (FLA) times the multiplier shown in the table to determine Suggested Minimum Size Fuse. Use fan-cooled Primary FLA with Forced air transformer multiplier. See Tables 3, 4, and 5 for suggested minimum fuse size.

For Self-CooledTransformers

For Forced AirTransformers

Type CLE, CLE1, CLE2 Current Limiting FusesType RBA Expulsion Type Non-Current Limiting Fuses

All Ratings 1.4 x FLA of XFMR 1.2 x FLA of XFMR

➁

The type RBA interrupting ratings shown are those of the discharge filter type, in which the noise is minimized and deionization of expulsion gases is assured.

May 2001

CAT.71.01.T.E

Cutler-Hammer


Technical Ratings

For single line-to-ground fault;

X

I

= X

I

(+) + X

I

(-) + X

I

(0)

Step 6 – Select a fuse whose pub-lished interrupting rating exceeds the calculated fault current.

Table F8 should be used where older fuses asymmetrically rated are involved.

The voltage rating of power fuses used on three-phase systems should equal or exceed the maximum line-to-line voltage rating of the system. Current limiting fuses for three- phase systems should be so applied that the fuse voltage rating is equal to or less than 1.41 x nominal sys-tem voltage.

IfEXI----- 3×=

Interrupting Ratings of Fuses

Modern fuses are rated in amperes rms symmetrical. They also have a listed asymmetrical rms rating which is 1.6 x the symmetrical rating.

Refer to ANSI/IEEE C37.48 for fuse interrupting duty guidelines.

Calculation of the fuse required

interrupting rating:

Step 1 – Convert the fault from the utility to percent or per unit on a convenient voltage and kVA base.

Step 2 – Collect the X and R data of all the other circuit elements and convert to a percent or per unit on a convenient kVA and voltage base same as that used in Step 1. Use the substransient X and R for all genera-tors and motors.

Step 3 – Construct the sequence net-works using reactances and connect properly for the type of fault under consideration and reduce to a single equivalent reactance.

Step 4 – Same as above except using resistances (omit if a symmet-rically rated fuse is to be selected).

Step 5 – Calculate the E/X

I

value, where E is the prefault value of the voltage at the point of fault normally assumed 1.0 in pu. For three-phase faults E/X

I

is the fault current to be used in determining the required interrupting capability of the fuse.

Note:

It is not necessary to calculate a single phase-to-phase fault cur-rent. This current is very nearly /2 x three-phase fault. The line-to-ground fault may exceed the three-phase fault for fuses located in generating stations with solidly grounded neutral generators, or in delta-wye transformers with the wye solidly grounded, where the sum of the positive and negative sequence impedances on the high-voltage side (delta) is smaller than the impedance of the transformer.

3

Table 2: Suggested Minimum Current Limiting Fuse Current Ratings for Self-Cooled 2.4-15.5 kV Power Transformer Applications

➀

SystemNom. kV

2.4 4.16 4.8 7.2 12.0 13.2 13.8 14.4

Fuses Max. kV

2.75 5.5 5.5 8.3 15.5 15.5 15.5 15.5

Trans-former kVA Rating Self-Cooled

% Z Full Load Current Amperes

CLEFuseRating Amperes

➀

Full Load Current Amperes


➀



➀



➀



➀



➀



➀



➀

Three-Phase Transformers

112.5150225300500

2.253.03.05.05.0

27 36 54 72120

40 50 75100200

16 21 31 42 69

25 30 50 65100

14 18 27 36 60

25 25 50 50100

9 12 18 24 40

➁

➁

30 40 65

5 7 11 14 24

➁

➁

➁

30 40

5 7 10 13 22

➁

➁

➁

30 30

5 6 9 13 21

➁

➁

➁

➁

30

5 6 9 12 20

➁

➁

➁

➁

30

7501000150020002500

5.755.755.755.755.75

180241361481601

250350600750

–

104139208278347

150250300400600

90120180241301

125200250350450

60 80120160200

100125200

– –

36 48 72 96120

50 65100150200

33 44 66 87109

50 65100150175

31 42 63 84105

50 65100125175

30 40 60 80100

50 66100125150

➀

Fuse ratings represent the smallest fuse pos-sible that will withstand transformer inrush (12XFLA for 0.1 sec. and 25XFLA for .01 sec.) and be able to handle temporary overloads (133% of FLA).

➁

While CLE Type fuses are not available at ratings low enough to protect these trans-formers, there are other current limiting style fuses available.

CAT.71.01.T.E

Cutler-Hammer

B4-8

May 2001


Technical Ratings

Table 3: Suggested Minimum RBA Expulsion Fuse Current Ratings for Self-Cooled 2.4-15.5 kV Power Transformer Applications

➀

SystemNom. kV

2.4 4.16 4.8 7.2 12.0 13.2 13.8 14.4

Fuse Max. kV

8.3 8.3 8.3 8.3 15.5 15.5 15.5 15.5

Trans-former kVA Rating Self-Cooled


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


112.5 150 225 300 500

27 36 54 72120

40E 50E 80E 100E200E

16 21 31 42 69

25E 30E 50E 65E100E

14 18 27 36 60

20E25E40E50E

100E

9 12 18 24 40

15E20E25E40E65E

5 7 11 14 24

10E10E15E20E40E

5 7101322

7E10E15E20E30E

5 6 91321

7E10E15E20E30E

5 6 91220

7E10E15E20E30E

75010001500200025003750

180241361481601–

250E400E540E

➂

720E

➃

––

104139208278347–

150E200E300E400E540E

➂–

90120180241301

–

125E200E250E400E450E➄

–

60 80120160200–

100E125E200E250E300E

–

36 48 72 96120180

50E 80E100E150E200E250E

33 44 66 87109164

50E 65E100E125E150E250E

31 42 63 84105157

50E 65E100E125E150E250E

30 40 60 80100150

50E 65E 65E125E150E250E

➀ Fuse ratings represent the smallest fuse pos-sible that will withstand transformer inrush (12XFLA for 0.1 sec. and 25XFLA for .01 sec.) and be able to handle temporary overloads (133% of FLA).

➁ Two (2) 300 E-Ampere fuse refills used in parallel with 10% derating factor.

Table 4: Suggested Minimum RBA Expulsion Fuse Current Ratings for Self-Cooled 25.8 to 38.0 kV Power Transformer Applications

SystemNom. kV

22.9 23.9 24.9 34.5

Fuse Max. kV 25.8 25.8 25.8 38.0

Transformer kVA Rating Self-Cooled


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


FuseE-AmpereRating


75010001500200025003750

192538506395

30E 40E 65E 80E100E150E

182436486091

25E 40E 50E 80E100E150E

172334465887

25E 40E 50E 65E 80E125E

131725334263

20E 25E 40E 50E 65E100E

➂ Two (2) 400 E-Ampere fuse refills used in parallel with 10% derating factor.

➃ Two (2) 250 E-Ampere fuse refills used in parallel with 10% derating factor.

May 2001

CAT.71.01.T.E

Cutler-Hammer B4-9Medium-Voltage Distribution EquipmentPower and Distribution Class FusesTypical Specifications

Typical SpecificationsThe medium-voltage fuses shall be [general purpose type current limit-ing] [backup type current limiting] [boric acid type expulsion] fuses. The fuses shall be designed to oper-ate with the [load interrupter switch-gear] [medium voltage motor starter] and shall be tested and rated in accordance with the latest ANSI standards.

References

The medium-voltage fuses shall meet the requirements of ANSI standards C37.40 to C37.47 and NEMA SG2.

Qualifications

For the equipment specified herein, the manufacturer shall be ISO 9001 certified. The manufacturer of this equipment shall have produced similar electrical equipment for a minimum period of five (5) years. When requested by the Engineer, an acceptable list of installations with similar equipment shall be provided demonstrating compliance with this requirement.

Products

Manufacturers

Cutler-Hammer or equal.

Ratings

Fuse ANSI _____ [C] [E] [R]Fuse Type _____ [CLE] [HLE]

[RBA][CLS] [CX/CXN][CLPT]

Nominal System Voltage _____ kVMaximum Design Voltage _____ kVCurrent Rating _____ AmperesInterruptingRating _____ kA RMS Sym

Construction

A. The following features shall be included on every current limit-ing fuse:

1. High purity, graded silica-sand filler with pure silver (.999 fine) elements encased in a glass-epoxy casing.

B. The following features shall be included on every boric acid expulsion fuse:

1. Fuse refill shall be hermetically sealed to prevent water ingress.

2. Fuse casing shall be glass-epoxy.

Fuse Features

A. CLE Type Fuses

1. The CLE current limiting fuse shall be general purpose.

2. 5 kV and 8.3 kV fuses, through 450E shall be 3 inches in diam-eter and shall be 17-7/8 inches in length.

3. 15.5 kV fuses shall be 3 inches in diameter and 23-7/8 inches in length.

4. The CLE shall have a blown fuse indicator.

B. HLE Type Fuses

1. The HLE current limiting fuse shall be general purpose.

2. The HLE type fuse shall be 3 inches in diameter and have 12-inch clip centers, up to 8.3 kV, and 15-inch clip at 15 kV.

3. The HLE type fuse shall have a striker pin that delivers approximately 3 Joules of energy over a 5/8-inch travel upon fuse operation.

4. The 5.5 maximum kV HLE fuses can be applied to lower kV systems.

5. The HLE type fuse ferrules shall be hermetically sealed.

C. RBA Type Fuses

1. The RBA expulsion type fuse shall be E-rated.

2. The RBA type fuse shall have a blown fuse indicator as part of the shunt and spring assem-bly. The blown fuse indicator shall operate in both discon-nect and non-disconnect fuse mountings.

3. The 8.3 maximum kV RBA fuse shall also be applicable to sys-tems lower than 8.3 kV.

D. CLS Type Fuses

1. The CLS current limiting type fuses shall be R-rated.

2. The CLS type fuse shall have a blown fuse indicator.

E. CX/CXN Type Fuses

1. The CX/CXN current limiting type fuse shall be C-rated.

2. The CX/CXN type fuse shall have 5/8-inch fuse ferrules.

F. CLPT Type Fuses

1. The CLPT/NCLPT current limiting fuse shall be general purpose.

2. The CLPT fuse shall have blown fuse indicator.

CAT.71.01.T.E

Cutler-HammerB4-10May 2001


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