Westinghouse Gfr series User manual

Instructions

for

Type

GFR

Ground

Fault

Protection

Systems

with

Automatic

Test

Panel

TABLE

OF

CONTENTS

Section Page

1.0

2.0

3.0

4.0

4.1

4.2

4.2.1

4.2.2

4.2.2.1

4.2.2.2

4.3

4.3.l

4.3.1.1

4.3.1.2

4.3.1.3

5.0

5.1

5.2

5.3

5.4

5.5

5.5.1

5.5.2

5.5.3

5.6

5.6.1

5.6.2

5.6.3

5.6.4

5.6.5

5.7

UL Listing

...................

.

General Purpose

...............

.

Description

..................

.

Application Considerations

........

.

General

...................

.

Methods

of

Achieving System

Selectivity

.................

.

Time Current Band Settings

....

.

Zone Selective Interlocking

....

.

Zone Selective Interlock

Wiring

................

.

Zone Interlocking Operation

Mode

................

.

Relay Settings

...............

.

General

.................

.

Single Zone

of

Protection

...

.

Multiple Zones

of

Protection -

Without Zone Interlocking

...

Multiple Zones

of

Protection -

With Zone Interlocking

.....

.

Relay Type Selection

............

.

Available Relay Types

.........

.

Setting Adjustments

...........

.

Ground Fault Signal Memory

.....

.

Time-Current Curves

..........

.

Relay Selection, General.

.......

.

Pick-up Range

.............

.

Type

of

Selectivity

.........

.

Type

of

Operation

..........

.

Relay Electrical Ratings

........

.

Control Power Required

......

.

Test Winding Power Required

..

.

Output Contacts

...........

.

Zone Interlock Contacts

......

.

Maximum Dielectric

.........

.

Mounting Arrangements

........

.

2

3

4

5

6

8

Effective September, 1985 Supersedes I.L. 15321-B dated August, 1982

Section

5.8

5.8.1

5.8.2

5.8.3

6.0

6.1

6.2

6.2.1

6.2.2

6.2.3

6.2.4

7.0

7.1

7.2

7.3

7.4

7.4.1

7.4.2

7.4.3

7.4.4

7.4.5

7.5

7.6

8.0

8.1

8.2

9.0

9.1

10.0

10.l

10.2

10.3

l.L.

15321.('

File 29-700

Connection Diagrams

..........

.

Relay Connections. . . . . . . . .

..

Typical System Diagrams . . . . . .

Zone Differential

GFR

Operation Principles. . . . . . . .

..

Ground Fault Current Sensors

......

.

General Description

...........

.

Electrical Ratings

............

.

Maximum System Voltage

.....

.

Withstand

...............

.

Dielectric Withstand

.........

.

Maximum Error Signal

.......

.

Ground Fault Test Panel

..........

.

General Description/Purpose . .

...

.

Available Types

..............

.

Electrical Data

..............

.

Operation Sequence

...........

.

Normal Operating Condition

...

.

If

Ground Fault Occurs

......

.

Action Required

...........

.

Test Without Service

Interruption

..............

.

Test With Service Interruption

..

.

Connection Diagrams . . . . . .

....

.

Alternate Test Diagrams

........

.

Ground Fault Warning Indicator Relay .

General Purpose . . . . . . . . . . . . . .

Available Styles

..............

.

Ground Fault Indicating Ammeter

...

.

General Purpose/Description

.....

.

Performance Testing

............

.

Code Requirements . . . . . . . . . . . .

Standards Requirements

........

.

General Test Instructions

.......

.

Page

10

11

14

17

20

21

23

Courtesy of NationalSwitchgear.com

2

!----.---Adjusting

Switches

Turn

Screw

to

Lock

Settings

Fig.

IA

Ground Fault Relay-ElectricalReset

With

Zone

Interlocking

(Cat.

No.

GFR60El)

1.0 UL LISTED GROUND FAULT SENSING

AND RELAYING EQUIPMENT

Type GFR ground fault relays, current sensors, test panels

and accessory devices are UL listed by Underwriters' Lab-

oratories, Inc. in accordance with their standard for

Ground Fault Sensing and Relaying Equipment, UL 1053,

under File E48381.

2.0 GENERAL PURPOSE

A type

GFR

ground fault protection system, when prop-

erly installed

on

a grounded electrical system, will sense

phase to ground fault currents. When the level

of

fault

current

is

in excess

of

the pre-selected current pick-up

and time delay settings, the GFR relay will initiate a trip

action

of

a disconnect device, which will open the faulted

circuit and clear the fault.

The GFR devices are UL

Class

I devices designed to

protect electrical equipment against extensive damage

from arcing ground faults.

CAUTION: GROUND FAULT PROTECTION SYSTEMS

DESIGNED TO PROTECT EQUIPMENT CANNOT

SIMULTANEOUSLY PROVIDE PROTECTION

FOR

PERSONNEL AGAINST ELECTRIC SHOCK HAZARDS,

SINCE THIS TYPE PROTECTION REQUIRES A SENSI-

TIVITY IN THE

LOW

MILLI-AMPERE RANGE.

-

---

Adjusting

Switches

Turn

Screw

to

Lock

Settings

Ground

Fault

Trip

Indicator-Depress

to

Reset

Fig.

lB

Ground Fault Relay-Mechanical Reset

With

Zone

Interlocking

(Cat.

No.

GFR60Ml)

Removable

Link

Removable

Link

Type

,____

___

Solid

Core

Type

Fig. 2 Typical Ground Fault Sensors

Courtesy of NationalSwitchgear.com

3.0

DESCRIPTION

A basic type

GFR

ground fault protection system consists

of

a ground fault relay (GFR)

as

shown in Fig. 1, a ground

fault current sensor (GFS)

as

illustrated in Fig. 2 and a

disconnect device equipped with a shunt trip device. This

disconnect device can be a molded case circuit breaker,

a power circuit breaker, a bolted pressure switch or

other

fusible disconnect device, suitable for application

with

UL Class I Ground Fault Sensing and Relaying equipment.

A typical molded case circuit breaker with a shunt trip

device installed

is

illustrated in Fig. 3.

Shunt

Trip

Fig.

3 Typical Shunt Trip Installation

Fig.

4A Ground Fault Test Panel Front

Component

Program

of

Underwriters'

Laboratories, Inc.

3

Additional optional equipment can be added to the

protection system

to

meet the requirements

of

the speci-

fying engineer, including:

1.

Ground Fault Test Panel -Figs. 4A,

4B

2. Ground Fault Warning Indicator Relay -Fig. 5

3. Ground

Fault

Indicating Ammeter© -Fig. 6

Fig.

4B

Ground Fault Test Pane/Back

Fig.

5 Ground Fault Warning Indicator

Relay

Courtesy of NationalSwitchgear.com

4

Fig. 6 Ground Fault Indicating Ammeter

4.0

APPLICATION CONSIDERATIONS

4.1 General

Type

GFR

ground fault protective devices are designed

to

be used primarily

on

solidly grounded electrical distribu-

tion systems rated

up

to

a

maximum

of

600

volts,

50/60

Hz, to provide for rapid clearing

of

arcing ground faults.

When properly applied, these devices will satisfy

the

requirements for ground fault

protection

of

service en-

trance

equipment

as outlined in Sections 230-95 and

517-14

of

the

National Electrical code. When these de-

vices are

added

to

downstream feeder and

branch

circuits

as

well as

the

main service disconnecting devices as sug-

gested in the fine

print

note

of

230-95

and

to

the down-

stream feeders as required in 517-14, additional protec-

tion will be provided and selective coordination

of

tripping

operations

on

arcing ground faults can be achieved.

With selectively coordinated ground fault

protection

equipment

applied

on

main service disconnects and

downstream devices, a greater degree

of

continuity

of

service

is

insured.

4.2

Methods

of

Achieving System Selectivity

There are two basic

methods

of

achieving selective coordi-

nation

between

different levels

of

ground fault protective

devices in a distribution system.

4.2. I TIME-CURRENT BAND SETTINGS

The first

method

employs adjustable time delay and cur-

rent pick-up settings

to

achieve selectivity between up-

stream and downstream devices. When properly coordi-

nated,

downstream

detection

devices will use a time-

current

band

setting

that

will initiate a downstream trip-

ping

operation

and clear the faulted circuit before any

upstream interrupting device tripping action can be ini-

tiated.

This

type

of

coordination necessarily requires

the

longest time delay settings

to

be placed

on

the upstream

devices. This

type

of

coordination

is

fine

if

the

faults are

always downstream.

4.2.2 ZONE SELECTIVE INTERLOCK/NG

In

a system employing zone selective interlocking type

devices, selective

coordination

is

still achieved for down-

stream faults

by

the use

of

time-current

band

settings.

With appropriate settings, downstream interrupting de-

vices will clear

the

faulted circuit before any upstream

device can operate. However,

with

zone selective inter-

locking, additional intelligence

is

automatically pro-

grammed

into

the

time-current

coordination

scheme

to

allow for variations

in

the

pre-established tripping

se-

quence

to

allow for alternate locations

of

the

arcing

ground

fault. A zone selective interlock coordinated sys-

tem

provides for fast tripping

of

the

nearest interrupting

device upstream

of

the

arcing ground fault regardless

of

the

pre-set time delay settings. With this

type

of

protec-

tion,

the resulting systems damage level

is

the

lowest

possible because

the

interrupting devices are allowed

to

clear

the

fault as quickly as

they

can respond.

4.2.2.I Zone Selective Interlock

Wiring

Zone

interlock wiring is only applicable

to

type

GFR

re-

lays equipped

with

zone selective interlocking as

shown

in

Table 1. These relays are equipped

with

four additional

terminals which have

the

following function:

Terminal 8 -

Common

(Not

used on l 25V

D-C

GFR's)

9 -

Output

signal

10 -

Input

signal, time restraint

11

-

Input

signal,

no

trip

To

make

the

relays function in a zone interlocking

mode,

all relays

must

be

of

the

interlocking

type

and

ad-

ditional wiring connections are required. Typical connec-

tions for a main

with

multiple feeders and multiple

branch

circuits

is

illustrated in Fig. 7.

As shown

by

Note l in Fig.

7,

twisted pair wiring must

be used for interlock wiring

to

reduce

the

influence

of

stray

magnetic fields in switchboards with high ampacity

bus systems. Interlock wiring

must

be

routed

away from

bus

bars and separate from

concentrated

control

wire

groupings.

Courtesy of NationalSwitchgear.com

Zone

I

Zone

3

Notes:

Time

Delay

Input

Typical

Mdlrl

GFR

Typical

Feeder

~

GFR

s

~

s

~

E

.=

Typicdl

Brandi

GFR

s

5

I.

W1nng

Should

be

Twisted

Pair,

Number

14

or

16

AWG

With Maximum Distance Between

First

and

Last

Zones

of

250

Feet

Route

Separate

from

Power

Conductors

Do

Not

Ground.

On

125VDC

GFR's

the

Wire

to

Terminal B

is

Not

Used.

Only

One

125VDC

Source

1s

Allowed

2.

Jumper

may

be

Added

Between Terminals 9

and

10

on

Downstream

Relays

to

Add

Time

Delay

per

Dial

Setting

Otherwise.

Relay

will

ln1t1ate

Trip

Without

Time

Delay

3.

Any

Quantity-Up

to

50-Relays

may

be

Wired

in

Parallel

to

Provide

a

Single

Upstream Restraint

Signal

4.

All

Relays

in

a

Zone

Interlock

System

Must

be

of

Interlocking

Type

Fig. 7 Connection

Diagram

for Typical Zone Selective Interlocking System

As

shown by Note 3 in Fig. 7, any number -up

to

50 -type GFR relays may be wired in parallel

to

trans-

mit a single signal

to

upstream device. No supplementary

relaying

is

required for this function.

4.2.2.2 Zone Interlocking Operation Mode

Regardless

of

the time delay setting, any interlocking type

GFR

relay will respond near instantaneously unless a

re-

straint signal -which

is

indicative

of

a ground fault further

downstream in the next protective zone -acts to change

the mode

of

operation

to

the pre-set time delay. On

downstream circuits, it

is

frequently desired

that

a short

time delay be observed before a tripping action

is

initiated.

This can be accomplished by adding a jumper between

terminals 9 and 10

on

the downstream relay

as

indicated

by Note 2 on Fig. 7. This jumper should

not

be used

on

any upstream relay

as

it will defeat the zone interlock-

ing function.

4.3 Relay Settings

4.3.1 GENERAL

The exact individual relay time/current settings will vary

between system installations depending upon the type

of

protection and level

of

selectivity desired. The Specifying

Engineer can best make these decisions for any specific

installation. For general applications, settings

as

described

in the following conditions may be considered.

4.3.1.1 Single Zone Level

of

Protection

Minimum Pick-up -

20%

of

disconnect rating. Increase

to

maximum pick-up setting (1200 Amp) where maxi-

mum service continuity

is

desired.

Minimum Time Delay© -10 cycles suggested. Any faster

time will invite nuisance trips. Increase time when more

than minimum damage level can be tolerated.

4.3.1.2 Multiple Zones

of

Protection Without Zone

Interlocking

Minimum Pick-up -The pick-up setting

of

the down-

stream device should still

be

no

less

than

20%

of

the

disconnect rating. Successive upstream settings should

be at least one step greater than the nearest downstream

device pick-up setting.

Minimum Time Delay© -The shortest time possible

should be used

on

the branch circuit downstream. In-

crease the time delay

on

upstream devices in increments

of

one step or more for molded case breakers, and two

steps or more for other slower operating type devices.

Courtesy of NationalSwitchgear.com

6

Table 1

120 Volt,

50/60

Hz

Control 120 Volt

De

Control

Style 1293C47

<!)

Style l293C83

<D

GFR Relay Cat. No. GFR @ @ Cat. No. GFR

<al

@

Types®

Pick-up In Amperes Pick-up In Amperes

1-12 5-60 100-1200 1-12 5-60 100-1200

Electrical Reset

Gll

GOl

G03

Gl

l GOl G03

With

Zone Interlocking 12EI 60EI 1200EI 12EID 60EID 1200EID

Electrical Reset

Gl2

G02 G04

Gl2

G02 G04

Without

Zone Interlocking 12E 60E 1200E 12ED 60ED 1200ED

Mechanical Reset G09

GOS

G07 G09

GOS

G07

With

Zone Interlocking 12MI 60MI 1200MI 12MID 60MID 1200MID

Mechanical Reset GlO G06 G08 GlO G06 G08

Without

Zone Interlocking

12M

60M

1200M 12MD 60MD 1200MD

©For

complete style number, add group suffix from below,

as

G11, GOl, G03.

@For

complete catalog number, add suffix from below,

as

12EI, 60EI, 1200£1.

@All types require 120 volt,

50/60

Hz. control for test winding.

C!>

After March, 1983, an

"A"

suffix will be included after the

GFR

style number to signify

that

the

GFR

interlock

is

comparable

with the

SPB

and Digitrip interlocks.

4.3.1.3 Multiple Zones

of

Protection

With

Zone

Selective Interlocking

Establish time/current coordination

as

in 4.3.1.2 for

multiple zones without zone interlocking. This

is

done

on the basis

that

most faults occur downstream and that

the most downstream device should be set to clear the

fault first leaving upstream devices for back-up fault

protection.

Add zone interlocking to provide fast tripping

of

up-

stream devices regardless

of

pre-set time delay for faults in

the upstream zones.

Where

desired, nearly instantaneous operation

of

down-

stream devices can be defeated were time delayed op-

erations are adequate. See 4.2.2.2.

5.0 RELAY TYPE SELECTION (See Fig. 1)

5

.1

Available Relay Types

The GFR ground fault relays are available in two basic

types, ie, with and without zone selective interlocking.

Each type relay must be reset following a trip operation.

Each

of

the basic type relays

is

available with either an

electrically held or mechanically latched

output

relay. The

electrically held type must be electrically reset remotely -

usually

via

a normally closed, momentary pushbutton in

the control power circuit. In this type, a red lamp

is

pro-

vided for visual ground fault trip indication. The mechani-

cally latched type must be manually reset by depressing

the pushbutton on the face

of

the GFR relay. This manual

reset

bottom

also serves

as

a mechanical pop-up trip indi-

cator. A complete list

of

available styles

is

provided

in

Table

1.

5.2 Setting Adjustments

Each type relay

is

provided with two switches that are

adjustable over the range selected. The top adjusting

knob,

as

shown in Fig. 1, adjusts the pick-up level

of

the

ground fault current. The bottom adjusting knob adjusts

the time delay range. The calibration marks provided for

both

adjustments

are

shown in Table 2. After the desired

values have been pre-set, the adjusting knobs can be

locked in position by the pointer lock screw shown in

Fig.

1.

5.3 Ground Fault Signal Memory

Arcing ground fault currents are, by definition, erratic

in

nature being caused by the intermittent striking and

re-

Courtesy of NationalSwitchgear.com

~--...-----r----+-----+-

-

t-

+-

+ t t +

-+----.-

_..,. •

--+----1-t

--

-+--

-;

• --.-+---i-

~

+- -

-++++--r+---

----~-~--+-!++~

----+---------~--+

...-+,-

3~-·+

....

~---+---+--+++-»---r+----

------,-·

·+~~---1-

r

2---.-+f-<

~--

--+!-<-

---+---

~~-+,1+---J_

-

~

44

-

-+--

~

I •

~

+ •

--r-~-

..

.....

~t-

•

·---~10

++-~3

·-~-2

1----.-~-+H

__:__:___-_-=_+--

;.:-:H=-.-~:_:____

· ·

+-

+

s~~~~

-t-+--+

-:J-+-=--:--:-:---

r-~~-~~

.

so.

i.

L .

--1

.._

-+--4--+

._..

1---

-+-~·1

___

.,.

-----r_____._

-~-

J--..-

~~==

--

1:

5r-t-·+

-t-

h-

f---

+

--

+---+I-+

~+---;-----r-

-+--__,____,____+-....-

~+--

~

i - -

'"

I;

t+

.-

J:---------+-

t-t-

----r---+

~-

------+-----+--- t -+-+-+--

01~

...-

----------+--t+

-=---=1-

--+--

+ • •

r-+-+

---+-

.,.

•---------+---+-

--,,

005--

,_,_.---

--+----+-

+ +

-+----+--f-+

003----+-+--

----+---1 ---+----t-+

+~

+----+---+-•

--+--+--

I

t +

~

--+

+.

DOI--·-

- .

~

Fig.

8 GFR Relay Time-Current Curve

+--

....

-;--+--+-----

1---

+-

•

T--+---t

+•

•-+-

--+--·

..

+-+----

Cl

0 0 0 G

M

~

0

MINIMUM

PICK

UP

SEITINGS.

AMPERES

• j

+.

·-

-

--.-

-++---

t+----

-

...

+~-+--+-1-

.----+-+

....

+

+-+-

. :-::-::t

--

+-----r-+-+r

-+

+---r--+---+-+

...

-+-+---+T-

a

.

~--113

--

~.

·---02

·---

-

..

-

005

+

••••

003

••.

-

002

Courtesy of NationalSwitchgear.com

8

striking

of

an arcing ground fault. To avoid the instanta-

neous resetting

of

the solid state timing circuitry every

time the fault current drops

to

zero, Type GFR ground

fault relays are equipped with a memory response, which

integrates these intermittent faults with time using a seven

second time constant.

Table 2

Pick-up

Amperes Dial Marking*

1-12 1 2 3 5 7 9 12

5-60 5 10

15

25 35 45 60

100-1200 100 200 300 500 700 900 1200

Time Delay I 10

15

25 35 45 60

Cycles

*All Adjustments

are

in discrete steps.

5.4 Time-Current Curves

The time/current performance curve

of

a Type GFR

re-

lay has a flat response, ie., the operating time

of

any given

fault current above its pick-up setting

is

essentially con-

stant. There

is

some small variation in the lower ranges

as

indicated in Fig. 8, but very little. The pick-up and time

delay tolerances,

are±

10%.

5

.5

Relay Selection, General

The specific type and pick-up range

of

relay selected

is

a factor

of

its intended application, which the specifying

engineer can best determine. In general, the ratings may

be selected

on

the following general basis:

5.5. I PICK-UP

RANGE

1-12 Amp -Specific circuit application where low level

sensitivity

is

required.

5-60 Amp -Individual branch and/or motor circuits

where multi-level protection

is

provided.

100-1200 Amp -General purpose and service applications.

5.5.2 TYPE OF

SELECTIVITY

Relays without zone interlocking are best suited for single

level applications where it

is

desired

to

only satisfy the

minimum requirements

of

the National Electrical Code.

Zone selective interlocking type relays should be selected

for multi-level system applications where only the mini-

mum amount

of

system damage can be tolerated follow-

ing an arcing ground fault.

5.5.3

TYPEOFOPERATION

Electrically held relays will satisfy most applications

where reliable control power

is

available following a fault

interruption. Where control power

is

derived from the

load side

of

the disconnect device and a visual trip indica-

tion

is

desired, the mechanically held relay should be

selected. Also, in applications where the control power

is

less than reliable and where an automatic reset could

af-

fect interlocking circuitry, the mechanically held relay

should be selected.

5.6 Relay Electrical Ratings

5.

6.

I CONTROL POWER REQUIRED

120 Volts, 50/60

Hz.,

0.125 Amps, or

125 Volts de, 0.125 Amps

5.

6.2 TEST WINDING POWER REQUIRED©

120 Volts, 50/60 Hz., 2.5 Amps

5.6.3 OUTPUTCONTACTS

UL Heavy Duty Pilot Rating

240 Volts, 50/60

Hz.,

3.0 Amps Continuous, 30 Amps

Inrush

120 Volts, 50/60 Hz., 6.0 Amps Continuous, 60 Amps

Inrush

28 Volts, de, 3.0 Amps, Inductive Load

125 Volts, de, 0.5 Amps, Inductive Load

5.6.4 ZONE INTERLOCK -CONTACTS 8-9

Output Voltage, 6 Volts de

Rated Amps,

.01

Amps,

de

5.

6.5 MAXIMUMDIELECTRIC

Terminals to mounting screw 3000 Volts

5.7 Mounting Arrangements

The type GFR Relay

is

supplied

as

standard in a surface

and semi-flush mounted enclosure with outline dimen-

sions

as

illustrated in Fig. 9. For installations requiring a

semi-flush cover mounting, panel cutout and mounting

dimensions are illustrated in Fig. 10.

Courtesy of NationalSwitchgear.com

i:-:

2.375

2

531

I

Cutout

--'----'--'--+------

_-

_

__...__

-_-_-_-:_-$--'

T

Fig.

10

Flush Cover Mounting Details for Type GFR

Ground Fault Relay

Fig.

9 Outline

of

Type GFR Ground FaultRelay

Current

Sensor

Input

Terminals

8-11

Current

Pick-Up

Adjustment

Zone

Interlock

Time

Delay

Adjustment

I

_J

Output

I-----'

Driver

I

________

_J

Supplied

on

R

(+)

Power

Supply

(-)

Control

Power

120

Volts.

50/60

Hz

Zone

Interlock

rD

c~-n-ly

~----8_§_@

______

@]

____

~

---

~

______

j

Zone

Interlock

Signals

Fig.

11

Block Diagram for Typical GFR Ground Fault Relay

Trip

Contacts

G)

Omit

on

Mechanical

Reset

Relays

(D

Omit

on

Electrical

Reset

Relays

9

Courtesy of NationalSwitchgear.com

10

5.8 Connection Diagrams

5.

8.1

RELAY

CONNECTIONS

A simple block diagram

is

provided in Fig.

11

to illus-

trate the internal functional circuits

of

the type GFR

Relay. Complete external connections are a function

of

the associated devices used with the relay along with the

complexity

of

the system in which the components are

applied. The terminals on the

GFR

relay are suitable for

#18 through

#14

AWG

copper conductors. A maximum

of

two per terminal are permitted.

5.8.2 TYPICAL SYSTEMDIAGRAMS

Basic, typical radial distribution system diagrams are pro-

vided

in

this leaflet for guidance; refer to Figs. l

lA,

118,

llC,

llDand

llE.

Two multiple source distribution systems are illus-

trated in Figs.

11

F and l

lH.

Fig.

11

F illustrates a dual

source distribution system with center point grounding

as

allowed in the National Electrical Code under Article

250-23a, Exception No. 4 Fig.

11

H illustrates a multiple

source, multiple ground distribution system with zone dif-

ferential ground fault sensing methods employed.

5.8.3 ZONE DIFFERENTIAL GFR OPERATION

PRINCIPLES -SEE

FIG.

l JH

5.8.3.1 In general,

G~~

will operate only for ground

faults within Zone 1 and

G~~

for Zone 2. This includes

ground faults for feeders located in these respective zones.

5.8.3.2 With

"Ml"

and

"T"

closed and "M2" open and

with a ground fault in Zone

2,

G~~

will not operate

to

trip

"Ml"

but,

G:~

will

to

trip

"T".

5.8.3.3 Conversely, with "M2" and

"T"

closed and

"Ml"

open and with a ground fault in Zone 1,

G:~

will not op-

.

"M2"

b GFR

·11

.

"T"

erate

to

tnp

ut

M2

w1

to

tnp

.

5.8.3.4 For properly co-ordinated main, tie and feeder

interrupting devices, the feeder relays will always react

to clear a downstream ground fault prior

to

operation

of

either the main or tie devices.

5.8.3.5 Zone interlock wiring between upstream and

downstream devices can be included

as

shown. For this

scheme, no cross interlocking with

"T"

auxiliary contacts

is

required.

5.8.3.6 This scheme may be expanded to additional alter-

nate sources

as

long

as

interrupting devices are available

to

isolate any potential ground fault on each side

of

the

fault.

6.0

GROUND FAULT CURRENT SENSORS

(See Table 6, Page 24)

6

.1

General Description

As

indicated in Table 6 (Page 24), Ground Fault Current

Sensors (GFS) are available in a variety

of

physical sizes

and current ratings to match the application requirements

of

the distribution system. Sensors should be selected to

match the ampere rating

of

the specified

GFR

Relay. The

physical size should be selected to properly encompass the

required conductor configuration with space allowed for

minimum clearances

as

shown

in

the applicable outline

mounting figure. Outline references

are

given

in

Table 6.

Sensors are available with solid cores having round con-

ductor openings and in split core designs with various size

rectangular openings. On the split core designs, one core

leg

is

removable

to

permit ease

of

installation around

existing conductor assemblies.

Ground Fault Current Sensors are special rated current

transformers and must be applied only with type GFR

Relays shown in Table

1.

Sensors cannot be used with any

other equipment.

Sensors are insulated with cast apoxy and can be

mounted directly to enclosure surfaces. Ideally, they

should be installed

so

that all conductors passing through

the sensor opening are physically centered in the window

opening. Minimum clearances are specified in the applica-

ble outline,

but

greater clearances will help reduce any

possible error signals. Rectangular configurations are pro-

vided with compensating windings to reduce potential

error signals.

All

sensors are provided with integral test winding for

use under simulated ground fault test conditions. With

an input

of

1.2 Amps into terminals 2-3, a rated

output

of

240 M.A. should be produced in terminals

1-3

with a

tolerance

of

±15%. For information purposes, the turns

ra-

tio and saturation levels

of

all sensors

is

provided

in

Table 6.

Courtesy of NationalSwitchgear.com

6.2 Electrical Ratings

6.

2.1

Maximum System Voltage

600 V. @

50/60

Hz.

6.2.2 WITHSTAND

Primary Amps Time Seconds

200KA

50KA

@

4KA

~Except

1

KA

on 12A. Solid

6.2.3 DIELECTRIC WITHSTAND

0.05

0.3

Continuous

Windings to Mounting Holes - 3

KV

Windings to Inner Core Surface -3KV

Mounting Surface to Inner Core Surface -3KV

6.

2.

4 MAXIMUM

ERROR

SIGNAL -WITH

BOLTED PHASE THROUGH

FAULT

12A Solid

60A Solid

1200A Solid

60/

1200 A

R/L

1.0

A@

144A

5.0

A@720A

100

A@

14.4

KA

100

A@

15

KA

Neutral

Disconnect

Link

NEC

230-

75

Main

___

,.,._,__*

__

..._

___

~

c.

I

Grounding

Electrode

Conductor

Notes:

GFP

Sensing

Method

•Ground

Return

Type

of

Protection

GFS

"M

•Minimum

per

NEC

230-95

•

GFP

on

Mam

Only

Ground

Fault

Selectivity

~I

I

Polarity

Marks

Mam

Bonding

Jumper

Feeder)

Neutral

Equipment

Sround

Bus

•Marginal.

Function

of

Feeder

Rating

and

Time/Current

Curve

Ad1ustabil1ty.

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

Dtsconnect

per

NEC

250-23

ia).

Fig. 1

lA

Simple Radial System With GFR on Main

Only-Ground Return Sensing

Alternate

Sensor

Location

GfS

feeder)

Notes:

G

FP

Sensing

Method

•Zero

Sequence

Type

of

Protection

•

Mm1mum

per

NEC

230-95

•

Gf

Pon

Mam

Only

Ground

Fault

Selectivity

•Marginal.

function

of

feeder

Time/Current

Curve

Ad1ustab1l1ty

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

01sconnec1

per

NEC

250-23

Jal

•Must

Not

be

on

Downstream

Side

ol

Ground

Fault

Sensor

Load

Fig. l

lB

Simple Radial System With GFR on

Main

Only-Zero Sequence Sensing

Service

Source

Notes:

GfS

M

GFP

Sensing

Method

•Main-Ground

Return

•Feeders-Zero

Sequence

Type

of

Protection

~'-----------

*

Neutral

•Two

Level

tor

Improved

Service

Cont1nu1ty

as

Suggested

by

NEC

230

95

lbl

Ground

Fault

Selectivity

•Time/Current

Coordination

Between

Main

and

Downstream

Feeders

•feeder

Trtps

Before

Mam

tor

Downstream

faults

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

Disconnect

per

NEC

250-23

Ja)

Fig.

llC

Simple Radial System With GFR on Main and

Feeders-Ground Return Sensing on

Main

11

Courtesy of NationalSwitchgear.com

12

*

Main-'r•---:-a_in..,.zo._n_•=l

Notes:

GFP

Sensing

Metllod

•Mam

and

Feeders-Zero

Sequence

Type

of

Protection

•Two

Level

for

Improved

Service

Cont1nu1ty

as

Suggested

by

NEC

230-95

(b).

Ground

Fault

Selectivity

•Time/Current

Coordination

Between

Mam

and

Downstream

Feeders

•Feeder

Tnps

Before

Mam

for

Downstream

Faults.

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

Disconnect

per

NEC

250-23

(a)

•Must

Not

be

on

Downstream

Side

of

Ground

Fault

Sensor.

Neutral

Service

Source

M

Note:

See

Figure

7

for

Interlock

Wiring

Details

Notes:

GFP

Sensing

Metllods

•Mam-Ground

Return

•Feeders-Zero

Sequence.

Type

of

Protection

•Two

Level

for

Improved

Service

Continuity

•Zone

Selective

Interlocking

for

Minimum

Arcing

Fault

Damage

Ground

Fault

Selectivity

•Time/Current

Coordination

Between

Mam

and

Downstream

Feeders

•Feeder

Tnps

Before

Mam

for

Fault

in

Feeder

Zone.

•Mam

Trips

Without

Pre-set

Time

Delay

for

Fault

m

Mam

Zone

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

Disconnect

per

NEC

250-23

(a)

"'

0

N

"'

~

1

Fig. IID Simple Radial System With GFR on Main and

Feeders-Zero Sequence Sensing

on

Main Fig. I

IE

Simple Radial System With GFR on Main

and

Feeders With

Zone

Selective Interlocking

Service

Source

Number

1

Service

Source

Number

2

Note:

Control

Power

Must

be

Common

to

M1

/M2/T1e

GFR

Relays

Trip

, --

----

'

I

Mlr-----_J

Ml

a

Tie

M2

a

Trip

- -

---1

I

~----~

Neutral

01scorrnect

--

Bus

2

Ne1L1t-ra_IB_u_s

_1

_

_..~----------+----.-----T

_

------

Neutral

Tnp

ri-,----+--+----------1---.--=-=-"--'

Load

Not<s

GFP

Sensing

Method

•Main-Ground

Return

With

Polarities

Arrans~d

to

Avoid

Neutral

Unbalance

•Tie-Ground

Return

•Feeders

Zero

Se4uence

Type

of

Protection

•Multiple

Level

tor

Improved

Service

Contmwty

•Zone

Selective

Interlocking

May

be

Added

for

M1111111um

Arcing

Fault

Oa111age

(See

Figure

11

G)

Ground

Fault

Selectivity

•Time/Current

Coord1natt0n

Between Main

Tie

and

Feeders

•Feeder

Trips

Before

Ma111

or

Tie

for

Downstrea111

Faults

•Tie

Trips

Before

Marn

to

Sect1onal1ze

Main

Bus

*Additional

Grounding

•Anr

Add111onal

Grounding

Points

Must

be

Avoided

Fig. I

IF

Dual Source System Using CenterPoint Grounding (NEC250-23a-Exception No. 4)

Courtesy of NationalSwitchgear.com

CD

GFR

Mi

9

10

11

r--

1

G):

~+

cs

71

I

Typical

Bus

1

Feeder

I

L--

GFR

FT

11

Ml

a

GFR

Tie

M2

a

Tie

b

©

--,

G)

:

~-+

cs

-it-

1

I

__

__j

GFR

M2

9

10

11

CD

Typical

Bus

2

Feeder

GFR

Ti

11

Notes:

CD

All

Interconnections

Shown

Should

be

Twisted

Pair

CD

Additional

Feeder

GFR's

May

be

Added

in

Parallel

on

Either

Buslor2

13

G)

Add

Cell

Switch

Contacts

When

Tie

1s

Drawout

Construction.

@

Steering

Diodes

!Similar

to

1

N457)

Fig.

1lG Special Zone Interlocking

Wiring

that may be used with Dual Source System using Center Point Grounding

(See Figure JJF)

Zone

Ml

Feeder

Zone

Notes:

GFP

Sensing

Method

•Mains/Feeders-Zero

Sequence.

Type

of

Protection

•Two

Level

for

Improved

Service

Continuity

•Zone

Selective

Interlocking

for

M1mmum

Arcing

Fault

Damage

~~~~~~~~~~~~~-.~~---.

....

~-'--+-~--i-lH*-GFS

~

NoteG)

Tnp

ZSI

.,.I

Zone

M2

Note

CD

F2)+---;

Note

CD

Ground

Fault

Selectivity

•Zone

Differential

for

Fault

Area

Isolation

•Time/Current

Coordination

Between

Main

and

Downstream

Feeders

W1th1n

Zone

•Feeder

Tnps

Before

Main/Tie

for

Fault

1n

Feeder

Zone

•Mam

Tnps

Without

Pre-set

Time

Delay

for

fault

in

Main

Zone

*Additional

Grounding

•Not

Permitted

Downstream

of

Service

Disconnect

per

NEC

250-23

(a)

CD

Zone

Interlock

Wmng

Should

be

Twisted

Pair.

Refer

to

4 2 2 1

CD

Control

Power

for

GFA

MI.

GFA

M2

and

T

Should

be

Supplied

f

ram

Common

SoUTce

G)

Reier

to

58

3.6

Fig.

1IH Multiple Source, Multiple Grounded System Using Zone Differential Sensing

Courtesy of NationalSwitchgear.com

14

7.0 GROUND FAULT TEST PANEL (See Fig. 4)

7

.1

General Description/Purpose

The test panel

is

designed to test the ground fault cir-

cuitry

in

the type

GFR

Ground Fault Relay along with its

associated disconnect with a simulated, low-level test cur-

rent from a location remote from the disconnect using a

separate power source. Provisions are available to conduct

a test

in

either

of

two operational modes: By opening the

disconnect or by

not

opening the disconnect.

The test panel provides the easiest and most inexpen-

sive

method to conduct ground fault tests on a repeat

basis. Tests can

be

conducted by qualified maintenance

personnel during routine maintenance schedules.

+ +

----3.62---

+ + 1

WARNING: THERE

IS

A HAZARD OF ELECTRICAL

SHOCK

OR

BURN WHENEVER WORKING

IN

OR

AROUND ELECTRICAL EQUIPMENT.ALWAYS TURN

OFF

POWER SUPPLYING THIS EQUIPMENT BEFORE

WORKING INSIDE SWITCHBOARDS.

7.2

Available Types

The test panel

is

available only as a flush, cover

mounted

assembly under Cat. No. GFRTP or GFRTPD (for

d-c

control)

as

illustrated in Fig. 4.

It

is

provided with

switches for initiating the desired test sequence, a red

lamp to signify a ground fault trip operation, the avail-

ability

of

control power to the test panel, system reset

and

an

instruction nameplate. Outline dimensions are

shown in Fig. 12 with panel cut-out and drilling plan

details

in

Fig. 13.

See

Table

4,

List

of

Available Styles.

+

+ +

+

3.56

"Terminal

Block"

+

E_,.,_J

+

.156

Dia.

4

Holes

Fig. l

2A

Outline

of

Catalog No. GFRTPD and GFRTP Ground Fault Test Panels WithoutMounting Bracket

Courtesy of NationalSwitchgear.com

Table 4

GFR

Test Panel Style No.

Types

120 Vac

Control Power, 1276C40G01 1276C40G03

120 Vac Horizontal Vertical

Test Power Mounting Mounting

125 Vdc

Control Power, 1276C40G02 1276C40G04

120 Vac Horizontal Vertical

Test Power Mounting Mounting

.25

+ +

------6.50------

1+-----6.00-----

+ +

+

170

Die.

-4

Mounting

Holes

.25

5.50

5.00

Terminal

Block

~.06

.44

l+----3.81----.t

Fig.

128

Outline

of

Catalog No. GFRTPD and GFRTP Ground Fault Test Panels usingMounting Bracket,

1276C40G05

15

T

1.42

Courtesy of NationalSwitchgear.com

16

3.06

1.22

l

.170

Dia.

4

Holes

Fig. 12C MountingBracket 1276C40G05

3.06

1.75

I

2.66

~---l_ij

I

.20

1.02

i+-----3.81--------..l

.138-32

Tap

4

Holes

Fig. 13A Panel

Cutout

andDrilling Plan

for

Catalog

No. GFRTPD and

GFRTP

Ground Fault

Test Panels Without MountingBracket

.138-32

Tap

4

Holes

2.66

.20

5.50

Panel

Cutout

.170

Diameter

14)

Holes

_______..19--+H--~--

Top

-

-*

500

4.63

I

-s.62--§+-

______

6

00

:11

Fig. 13 Panel Cutout and Drilling

Plan

for Catalog

No. GFRTPD and GFRTP Ground Fault

Test Panels

Courtesy of NationalSwitchgear.com

7.3 Electrical Data

Test Winding

Requires a 120 Volt, 50/60 Hz. Control Power Source

(300 VA) for operation.

A-C

Control Circuit

Requires a 120 Volt, 50/60 Hz., 0.125 Amp Source; use

same source

as

Test Winding, above.

D-C

Control Circuit

Requires a

125

Volt d-c, 0.125 Amp Source.

7.4 Operation Sequence

7.4.1 NORMAL OPERATION CONDITION

Ground Fault Lamp

"OFF"

Control Power Lamp

"ON"

System Resetting Lamp

"OFF"

7.4.2

IF

GROUND

FAULT

OCCURS

1.

Circuit Breaker Trips Open

2. Ground Fault Lamp Turns

"ON"

3. Control Power Lamp Remains

"ON"

7.4.3 ACTIONREQUIRED

1.

Locate and clear the ground fault.

2.

Push and release the "reset"

button

on the test panel.

(The control lamp will

go

"OFF").

3. Push "indicator/reset"

button

on mechanically reset

GFR

relay while the "system resetting" light

is

"ON".

This will cause the "ground fault" lamp

to

go

"OFF"

and after a short time delay, the "control power"

lamp will turn

"ON"

and the "system resetting" lamp

turns

"OFF".

4. Now "reset" the circuit breaker and turn it back

"ON"

to restore service.

7.4.4 TEST WITHOUT SER VICE INTERRUPTION

1.

Press and release the "test without service interruption"

switch on test panel.

1.1

The ground fault relay trips.

1.2 The "ground fault" lamp turns "ON".

17

2.

After a short delay, the "control power" lamp turns

"OFF"

and the "system resetting" lamp turns

"ON".

3. IMMEDIATELY push the "indicator/reset" button on

the mechanically reset GFR relay. The "ground fault"

lamp will

go

"OFF".

CAUTION: The GRF relay must be reset

at

once, other-

wise the circuit breaker will trip open!

4. After a short delay (approx. 20 sec.) the "system

re-

setting" lamp goes

"OFF"

and the "control power"

lamp goes "ON". The system

is

now back to normal

and the sequence verifies it

is

operational.

7.4.5 TEST WITH SER VICE INTERRUPTION

1. Press and release the "test with service interruption"

switch on the test panel.

1.1

The GRF relay will trip, the circuit breaker will

trip and the "ground fault" lamp will

go

"ON".

1.2 Push "indicator/reset"

button

on the mechanically

reset GFR relay. The "ground fault" lamp will

go

"OFF"

and a momentlater, the "system resetting"

lamp will

go

"ON".

1.3 After this, the "system resetting" lamp will

go

"OFF"

and the "control power lamp" will

go

"ON".

1.4 Now reset the circuit breaker and turn it back on

to restore service.

7.5 Connection Diagrams

Fig. 14A illustrates the external connections required for

a complete GFP system using 120 volt

a-c,

50/60 Hz. con-

trol power, including: Type GFR Relay, a ground fault

sensor (GFS) and a test panel. A tabulation

is

also shown

to illustrate the various contact positions

of

the selector

switch and red lamp (switch). Fig.

14B

illustrates the

ex-

ternal connections required for

125

volt

d-c

control power.

Proper operation

of

the GFP system requires the

use

of

twisted wire connections on certain terminations.

Details

are

provided on the various connection diagrams

including Fig. 7. Refer also to 4.2.2.1.

The terminals on the test panel

are

suitable for #18

through #14

AWG

copper conductors. A maximum

of

two per terminal

of

the same

size

and type

are

permitted.

Courtesy of NationalSwitchgear.com

18

Source

Ground

Fault

Sensor

0

IGFSI

Contacts

Shown

1n

Normal

Position

Switch

Kl

K2 K3

I

Normal

0 0 0

L_

Reset x x 0

TestW/O

Tri

x 0 x

Test

WiTrip

0 0 x

Notes·

0 Refer

to

Outline

Drawings

of

Ground

Fault

Sensor Selected

to

Determine

Exact

Positioning

of

Polarity

Marks.

0

Twisted

Pair

Number

14 AWG

Minimum,

250

Foot

Maximum

IDo

Not

Route

With

Power

Conductors).

f3\

When

a

Control

Power

Transformer

is

Used,

Always

Connect

\V

Phase

to

Phase

Not

Phase

to

Neutral.

I

M--_-

____

T_o_E_l_ec_troni_cs

________

_J

When a

Mechanically

Reset Relay

IS

Used

with

a Test Panel,

Both

the

Relay

and

Test

Panel

must

be Reset

following

either

a

Simulated

Ground

Fault

Test

or

Actual

Ground

Fault

Unless

Noted

Otherwise,

Contacts

Shown

1n

De

Energized

Pos1t1on

Use

in

Motor

Starter

C1rcu1ts

Requires

Special Cons1derat1on. 1 e

Interruption

Capability

of

Contactor

Fig. 14A Connection Diagram for 120 Volt,

50/60

Hz Ground Fault Relay used With Test Panel

7.6 Alternate Test Diagrams

Where desired, alternate test schemes can be utilized

for periodic testing

of

the type

GFR

Relay and associated

disconnect using a simulated ground fault test current.

Two such test schemes are illustrated in Figs.

15

and 16.

The first figure illustrates the connections required for

an

electrically reset ground fault relay. The latter figure

is

for

a mechanically reset relay.

In

each

of

the alternate test diagrams, the suggested

test resistor rating

is

50 ohms, 70 watts. Using a 120 Volt

control power source, this will produce a test current

of

approximately 200%

of

the maximum pick-up setting

of

the

GFR

relay. Simulated field test methods should

not

be used

as

a calibration check

of

the relay. Functional

testing only should suffice.

Courtesy of NationalSwitchgear.com

Ground

Fault

Sensor

0

(GFSI

Ground

Current

Sensor

N A B c I

I I I* f Test

Winding

.........

_

_.__.

_

_._

___

\J

__

~_-.....

,...

I

"l""'

, '

:I

(:

' v

~

~ontrol

) Fuse

)

v

Signal

Winding

Top

View

Ground

Fault

Relay

r

'\.+-----------------....l/~C:J~~-S-1g_n_a_1

__

_

.....__

R

...

6 ..

'--

Control

Power

,

.........

_

___,f-----~-""---4-----'

/

..}__~--------

---1--L.--l.----J'7

13

r--i.

~

__/~LT

Contact

Shown

1n

De-energized Pos1t1on

19

Current

Limiting

Fuses DC I

-i•

.,.-i---

___

_.._,

DC

(+)<I~~-----+--~

~

Load

'.

I I I

0

~·

0 0

"'.

cr>

>"

-"'

~·

>-

-

a:

u~

,.a:

I

Switch

K1

K2

Normal

0 0

eset x

TestW/OTrin

X 0

Test W1

Trip

0 0

K3

0

x

x L

To

Electronics

-----------""'-

_.....;.

________

_

Notes·

0 Refer

to

Outline

Drawings

of

Ground

Fault

Sensor Selected

to

Determine

Exact

Posit1on1ng

of

Polarity

Marks.

0 Twisted Pair

Number

14

AWG

Minimum.

250

Foot

Maximum.

!Do

Not

Route

With

Power Conductors)

0 When a

Control

Power

Transformer

is

Used,

Always

Connect

Phase

to

Phase

Not

Phase·

to

Neutral.

Catalog No

GFRTPD

Test Panel

When

a

Mechanically

Reset

Relay

1s

Used

with

a

Test

Panel,

Both

the

Relay

and

Test

Panel

Must

be

Reset

Following

either

a

Simulated

Ground

Fault

Test

or

Actual

Ground

Fault

Unless

Noted

Otherwise,

Contacts

Shown

1n

De

Energ1Led Pos1t1on

Fig. 14B Connection Diagram for 125 Volt

DC

Ground Fault Relay used With Test Panel

Courtesy of NationalSwitchgear.com

20

Notes:

120

Volts,

50/60

Hz

Control

Power

Optional

A

Pilot

Lamp

L

Optional

!'Test

----

-

~Reset

CD

Refer

to

Outhne

Drawings

of

Current

Sensor

Selected

to

Determine

Exact

Positioning

Current

Sensor

iGFS)

CD

Test

of

Polarity

Marks

(D

Twisted

Pair·Number

14

AWG

Minimum.

250

Foot

Maximum

(Do

Not

Route

With

Power

Conductors)

G)

All

Pushbuttons

to

be

Momentary

Type

Only

Optional

Ground

Fault

Lamp

Contacts

Shown

1n

De·Energ1Zed

Position

Optional

Pushbutton

"No

Tnp"

Shunt

Tnp

Fig. 15 Connection Diagram for Electrical

Reset

Ground Fault Relay With Separate Test and

Reset

Devices

120

Volts.

50/60

Hz

Control

Power

Current

Sensor

iGFS)

CD

Optional

Pilot

Lamp

Signal

Test

L

Optional

J'iest

Resistor

Ohms.

50

Wans:

70

Top

View

Mechanical

Reset

Notes:

CD

Refer

to

Outline

Drawings

of

Current

Sensor

Selected

to

Determine

Exact

Positioning

of

Polarity

Marks

(D

Twisted

Pair·Number

14

AWG

M1n1mum.

250

Foot

Maximum

(Do

Not

Route

With

Power

Conductors)

G)

Hold

Depressed

During

Test

and

Until

Mechanical

Reset

is

Accomplished

0

All

Pushbuttons

to

be

Momentary

Type

Only

Optional

Ground

Fault

Lamp

Contacts

Shown

in

De-Energ1Zed

Position

Optional

Pushbutton

'No

Trip"

G)

Fig. 16 Connection Diagram

for

Mechanical

Reset

Ground Fault Relay With Separate Test Devices

8.0 GROUND FAULT WARNING INDICATOR RELAY

8.1

General Purpose

This relay, as illustrated in Fig.

5,

can be used

to

initiate

a remote audio or visual warning

of

a low level ground

fault condition. The non-adjustable relay

is

set

to

pick-up

at 30-50%

of

the pick-up setting

of

the associated type

GFR

relay. Thus, a warning

of

a slow progressing, high

resistance type

of

arcing ground fault can be triggered

prior to the circuit clearing actions initiated

by

the type

GFR

relay. The relay requires a 120 volt, 60 Hz., control

power source and must be used with a type

GFR

relay

equipped with zone selective interlocking.

8.2 Available Styles

The Ground Fault Warning Indicator Relay

is

a

UL

recognized component and available in four different

styles

as

indicated in Table

3.

One type

is

self-reset fol-

lowing a diminished pick-up signal. The other type

re-

quires an electrical reset

of

control power normally

accomplished by a pushbutton in the control power

circuit. The relay may be used individually for panel

mounting or, where extra signal contacts are required,

it may be used in conjunction with a type

BF

relay.

A typical connection diagram for a panel mounted relay

is

shown in Fig. 17.

Courtesy of NationalSwitchgear.com

Westinghouse GFR Series User manual

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