GE CEB52A User manual

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GEK

-

1291

H

INSTRUCTIONS

OFFSET

MHO

DISTANCE

RELAY

TYPE

CEB

52

A

GENERAL

ELECTRIC

Courtesy of NationalSwitchgear.com

GEK

-

1291

CONTENTS

PAGE

INTRODUCTION

APPLICATION

CALCULATION

OF

SETTINGS

RATINGS

3

3

3

4

CONTACTS

TARGET

SEAL

-

IN

UNIT

OPERATING

PRINCIPLES

OM

UNIT

-

ZERO

OFFSET

CHARACTERISTICS

OM

UNIT

-

WITH

OFFSET

OM

UNIT

-

ZERO

OFFSET

IMPEDANCE

CHARACTERISTIC

DIRECTIONAL

ACTION

...

.

UNDERREACH

MEMORY

ACTION

TRANSIENT

OVERREACH

.

..

OPERATING

TIME

TAPPED

AUTOTRANSFORMER

5

5

6

6

6

6

6

6

7

7

7

8

8

8

BURDENS

9

CURRENT

CIRCUITS

POTENTIAL

CIRCUITS

CONSTRUCTION

RECEIVING

,

HANDLING

AND

STORAGE

ACCEPTANCE

TESTS

VISUAL

INSPECTION

MECHANICAL

INSPECTION

ELECTRICAL

CHECKS

-

OM

UNITS

ELECTRICAL

TESTS

-

TARGET

SEAL

-

IN

UNIT

INSTALLATION

PROCEDURE

LOCATION

MOUNTING

CONNECTIONS

VISUAL

INSPECTION

MECHANICAL

INSPECTION

PORTABLE

TEST

EQUIPMENT

OFFSET

CHECK

ELECTRICAL

TESTS

ON

THE

OM

UNITS

.

..

.

INSPECTION

MHO

UNITS

PERIODIC

CHECKS

AND

ROUTINE

MAINTENANCE

.

.

CONTACT

CLEANING

SERVICING

CONTROL

SPRING

ADJUSTMENTS

OHMIC

REACH

ADJUSTMENT

ANGLE

OF

MAXIMUM

TORQUE

RENEWAL

PARTS

9

9

10

10

11

11

11

11

14

14

14

14

14

14

14

14

14

15

16

17

17

17

17

18

18

18

18

Please

check

your

previous

revision

to

This

instruction

book

has

had

a

major

revision

,

compare

material

.

NOTE

:

2

Courtesy of NationalSwitchgear.com

GEK

-

1291

OFFSET

MHO

DISTANCE

RELAY

TYPE

CEB

52

A

INTRODUCTION

The

CEB

52

A

relay

is

;

a

three

-

phase

,

high

speed

,

single

zone

directional

mho

distance

phase

relay

with

provisions

for

offsetting

the

characteristic

a

fixed

amount

.

It

is

constructed

of

three

-

single

-

phase

units

in

one

L

2

-

D

case

with

facilities

for

single

-

phase

testing

.

One

target

and

seal

-

in

unit

provides

indication

of

operation

on

all

three

units

.

The

transient

over

-

reach

characteristics

of

the

CEB

52

A

relay

have

not

been

limited

to

the

point

where

it

is

suitable

for

use

as

a

first

zone

relay

.

This

relay

was

designed

primarily

for

use

as

a

carrier

starting

relay

in

directional

comparison

schemes

.

It

is

also

applicable

as

a

second

or

third

zone

relay

in

straight

distance

schemes

.

APPLICATION

The

CEB

52

A

was

specifically

designed

for

application

as

a

carrier

starting

relay

in

directional

comparison

relaying

schemes

.

To

serve

this

purpose

the

relay

is

equipped

with

normally

closed

contacts

as

well

as

with

normally

open

contacts

.

Since

many

originally

straight

distance

terminals

are

later

converted

to

directional

comparison

terminals

,

the

CEB

52

A

should

be

used

as

the

third

zone

relay

in

straight

distance

schemes

to

facilitate

any

future

conversion

.

The

offset

feature

should

always

be

used

when

the

relay

is

employed

to

start

the

carrier

or

when

it

is

required

to

operate

in

conjunction

with

some

time

delay

for

zero

voltage

faults

.

In

carrier

starting

applications

the

normally

closed

contacts

are

closed

under

normal

conditions

to

hold

off

carrier

.

When

line

side

potentials

are

employed

,

and

the

line

is

deenergized

,

the

relay

will

have

no

electrical

restraint

and

will

depend

on

the

control

spring

to

provide

sufficient

contact

pressure

to

keep

carrier

turned

off

.

It

is

for

this

reason

that

this

relay

has

a

relatively

strong

spring

setting

.

Figs

.

5

and

6

give

the

operating

characteristics

for

this

relay

with

the

strong

spring

setting

,

with

and

without

offset

.

When

the

relay

is

employed

with

bus

potentials

,

or

if

it

is

used

in

straight

distance

schemes

,

a

weaker

spring

setting

may

be

employed

.

The

section

under

SERVICING

describes

how

the

spring

setting

can

be

changed

.

Figs

.

7

and

8

give

the

operating

characteristics

for

the

weaker

spring

setting

with

and

without

offset

.

The

CEB

52

A

will

be

calibrated

in

the

factory

with

the

strong

setting

.

The

CEB

52

A

relay

and

its

comparison

zone

packaged

relays

may

be

combined

in

several

different

ways

for

use

in

straight

distance

and

directional

comparison

relaying

schemes

.

Fig

.

17

illustrates

how

the

CEY

51

A

,

CEY

52

A

,

and

CEB

52

A

relays

plus

the

RPM

21

D

timing

relay

may

be

employed

for

three

zone

directional

distance

protection

of

transmission

circuits

against

all

multi

-

phase

faults

.

Separate

ground

fault

relays

are

required

for

single

-

phase

-

to

-

ground

faults

.

Fig

.

18

shows

how

these

same

distance

relays

plus

a

SAM

16

A

static

timing

relay

and

the

necessary

ground

and

auxiliary

relays

are

combined

in

a

directional

comparison

relaying

scheme

.

The

section

under

CALCULATION

OF

SETTINGS

provides

a

typical

worked

example

covering

the

setting

of

this

relay

.

CALCULATION

OF

SETTINGS

Consider

one

terminal

of

a

two

terminal

69

KV

transmission

line

,

17.3

miles

long

having

a

phase

-

to

-

neutral

impedance

of

Z

.

=

0.14

+

j

0.80

ohms

per

mile

prim

°

K

Z

=

17.3

(

0.14

+

j

0.80

)

=

2.4

+

13.9

ohms

total

These

instructions

do

not

purport

to

cover

all

details

or

variations

in

equipinent

nor

to

provide

for

every

possible

contingency

to

be

met

in

connection

with

installation

,

operation

or

maintenance

.

further

information

be

desired

or

should

particular

problems

arise

which

are

not

covered

sufficiently

for

the

purchaser

'

s

purposes

,

the

matter

should

be

referred

to

the

General

Electric

Company

.

To

the

extent

required

the

products

described

herein

meet

applicable

ANSI

,

but

no

such

assurance

is

given

with

respect

to

local

codes

and

ordinances

because

they

vary

greatly

.

Should

IEEE

and

NEMA

standards

;

3

Courtesy of NationalSwitchgear.com

GEK

-

1291

PT

Ratio

=

69

,

000

/

116

=

600

/

1

CT

Ratio

=

600

/

5

=

120

/

1

CT

Ratio

Zsec

^

prim

PT

Ratio

120

=

(

2.4

+

j

13.9

)

Z

=

0.48

+

j

2.78

ohms

sec

600

=

2.82

Z

_

80.2

°

ohms

Z

sec

Assume

that

the

CEB

52

A

is

to

be

used

to

provide

third

zone

protection

in

the

forward

direction

and

it

is

desired

to

set

the

forward

reach

for

6.0

ohms

at

an

angle

of

80.2

degrees

.

This

setting

having

been

arrived

at

after

due

consideration

to

coordinate

with

the

phase

relays

on

adjacent

circuits

and

taking

current

infeed

into

account

.

Case

I

-

No

offset

required

With

the

angle

of

maximum

torque

of

the

relay

at

75

degrees

,

the

percent

tap

setting

required

is

ob

-

tained

from

the

following

equation

.

100

(

3.0

)

Cos

(

80.2

-

75

)

Output

Tap

=

6.00

=

49.8

percent

Set

the

output

tap

at

50

percent

.

Case

II

-

Offset

required

Since

the

offset

setting

is

along

the

reactance

axis

on

the

R

-

X

diagram

,

it

is

easiest

to

arrive

at

the

proper

tap

setting

by

means

of

a

graphical

solution

as

outlined

below

.

1

.

Draw

the

R

-

X

diagram

as

in

Fig

.

2

.

Draw

line

0

A

at

the

impedance

angle

of

the

line

and

measure

off

the

length

to

be

protected

.

In

this

case

it

is

6.0

ohms

.

Through

the

point

S

,

representing

the

offset

,

which

in

this

case

is

(

R

=

0

,

X

,

=

0.5

)

,

draw

the

line

BC

at

the

angle

of

maximum

torque

for

which

the

relay

is

set

.

In

this

case

it

is

75

degrees

.

By

trial

and

error

draw

a

circle

which

has

its

center

on

line

BC

and

which

passes

through

both

points

P

and

S

.

This

circle

represents

the

desired

setting

.

Measure

the

diameter

of

the

circle

SM

.

In

this

case

it

measures

6.55

ohms

.

The

desired

OUTPUT

TAP

setting

in

percent

is

given

by

the

following

equation

:

(

100

)

(

Minimum

Reach

)

2

.

3

.

4

.

5

.

6

.

Output

Tap

=

Desired

Diameter

(

100

)

(

3.0

)

Output

Tap

=

45.8

6.55

Set

the

OUTPUT

TAP

for

46

percent

.

RATINGS

The

type

CEB

52

A

relays

covered

in

these

instructions

are

available

with

ratings

given

in

Table

I

.

4

Courtesy of NationalSwitchgear.com

GEK

-

1291

TABLE

I

(

Volts

)

(

Hertz

)

(

Amperes

)

120 120

120

120

120

Rated

Voltage

Rated

Frequency

Rated

Current

Basic

Ohm

Reach

Taps

Offset

Ohm

Tap

Angle

of

Max

.

Torque

*

*

One

Second

Rating

(

Offset

Out

)

(

Amps

)

One

Second

Rating

(

Offset

In

)(

Amps

)

60

60

60

50

60

5.0

5.0

5.0

5.0

5.0

1

/

2

/

3

2

/

4

/

6

1

/

2

/

3

1

/

2

/

3

0.5

/

1.0

/

1.5

0.5

0.5

0.20

0.5

0.25

75 75

75

75

75

260

1.45

260

260

260

145

225

90

90

145

**

The

angle

of

maximum

torque

can

be

adjusted

to

60

degrees

lag

with

the

connections

shown

in

^

21

f

°

r

the

top

unit

,

R

22

for

the

middle

unit

and

R

23

for

the

bottom

unit

,

but

the

reach

at

the

60

degree

setting

will

be

20

percent

less

than

the

reach

at

the

75

degree

setting

.

It

will

be

noted

that

three

basic

minimum

reach

settings

are

listed

for

the

OM

units

.

Selection

of

the

desired

basic

minimum

reach

setting

for

each

unit

is

made

by

means

of

links

on

a

terminal

board

located

at

the

back

of

the

realy

(

see

Fig

.

2

)

.

The

position

of

the

two

sets

of

links

,

(

for

each

unit

)

,

each

identified

as

A

-

B

determines

the

basic

minimum

setting

of

the

mho

units

.

The

basic

minimum

reach

setting

=

(

A

+

B

)

line

settings

.

The

ohmic

reach

of

the

OM

units

can

be

adjusted

in

one

percent

steps

over

a

10

/

1

range

for

any

of

the

basic

minimum

reach

settings

listed

in

Table

II

by

means

of

autotrans

-

former

tap

leads

on

the

tap

blocks

at

the

right

side

of

the

relay

.

The

OM

units

may

be

offset

.

Selection

of

either

zero

or

0.5

ohms

offset

is

made

by

means

of

links

on

terminal

boards

located

on

the

rear

of

the

relay

.

Fig

.

13

and

by

adjusting

CONTACTS

The

contacts

of

the

CEB

52

A

relay

will

close

and

carry

momentarily

30

amperes

DC

.

However

,

the

circuit

breaker

trip

circuit

must

be

opened

by

an

auxiliary

switch

contact

or

other

suitable

means

since

the

relay

contacts

have

no

interrupting

rating

.

TARGET

SEAL

-

IN

UNIT

The

target

seal

-

in

unit

used

in

the

CEB

52

A

relays

has

ratings

as

shown

in

Table

II

.

TABLE

II

TARGET

SEAL

-

IN

UNIT

0.6

2.0

0.2

2.0

Pickup

Rating

2.0

0.2

0.6

2.0

Tap

Used

Carry

30

amps

for

(

sec

)

Carry

10

amps

for

(

sec

)

Carry

continuously

(

amp

)

Minimum

operating

(

amp

)

Minimum

drop

-

out

(

amp

)

DC

resistance

(

ohms

)

60

Hz

impedance

(

ohms

)

50

Hz

impedance

(

ohms

)

3.5

0.5

0.05

2.2

30

5.0

0.45

20

2.6

1.2

0.37

2.3

2.0

0.6

0.2

2.0

0.5

0.15

0.05

0.5

0.18

0.78

8.3

0.24

0.65

6.2

50

0.65

0.54

5.1

42

0.54

2.5

amps

@

125

VDC

2.5

amps

@

175

VDC

DC

resistive

Interrupting

Rating

(

amps

)

5

Courtesy of NationalSwitchgear.com

GEK

-

1291

OPERATING

PRINCIPLES

OM

UNIT

-

ZERO

OFFSET

The

OM

units

of

the

CEB

52

A

relay

are

of

the

four

pole

induction

cylinder

construction

in

which

torque

is

produced

by

the

interaction

between

a

polarizing

flux

or

fluxes

proportional

to

the

restraining

or

operating

quantities

.

The

schematic

connections

of

the

mho

unit

are

shown

in

Fig

.

3

.

The

two

side

poles

,

energized

by

phase

-

to

-

phase

voltage

,

produce

the

polarizing

iflux

.

The

flux

in

the

front

pole

,

which

is

energized

by

a

percentage

of

the

same

phase

-

to

-

phase

voltage

,

interacts

with

the

polarizing

flux

to

produce

restraint

torque

.

The

flux

in

the

rear

pole

,

which

is

energized

by

the

two

line

currents

associated

with

the

same

phase

-

to

-

phase

voltage

,

interacts

with

the

polarizing

flux

to

produce

operating

torque

.

The

torque

at

the

balance

point

of

the

unit

can

therefore

be

expressed

by

the

following

equation

:

Torque

=

0

=

El

cos

(

0

-

9

)

-

KE

^

(

2

)

where

:

E

=

phase

-

to

-

voltage

(

E

12

)

I

=

delta

current

(

Ij

-

I

2

)

0

=

angle

of

maximum

torque

of

the

unit

0

=

power

factor

angle

of

fault

impedance

K

=

design

constant

To

prove

that

equation

(

2

)

defines

a

mho

characteristic

divide

both

sides

by

E

^

and

transpose

,

equation

reduces

to

:

The

1

—

cos

(

0

-

0

)

=

K

Z

or

:

Y

cos

(

0

-

0

)

=

K

Thus

,

the

unit

will

pick

up

at

a

constant

component

of

admittance

at

a

fixed

angle

depending

on

the

angle

of

maximum

torque

.

Hence

the

name

mho

unit

.

When

offset

is

used

the

transactors

(

01

,

02

and

03

)

are

energized

with

line

currents

and

introduce

a

voltage

(

proportional

to

the

current

)

added

to

the

line

-

to

-

line

voltage

received

by

the

units

.

This

voltage

offsets

the

circular

characteristic

of

the

OM

units

in

the

R

-

X

diagram

.

CHARACTERISTICS

OM

UNIT

-

WITH

OFFSET

When

the

offset

is

used

the

circular

characteristic

is

moved

along

the

X

-

axis

as

shown

in

Fig

.

4

.

OM

UNIT

-

ZERO

OFFSET

Impedance

Characteristic

The

impedance

characteristic

of

the

OM

unit

is

shown

in

Fig

.

4

for

the

three

ohm

basic

minimum

reach

setting

at

a

maximum

torque

angle

75

degrees

.

This

circle

can

be

expanded

by

means

of

the

mho

taps

on

the

autotransformer

tap

block

providing

a

range

of

up

to

10

/

1

,

or

by

changing

the

basic

minimum

reach

of

the

unit

by

means

of

the

links

on

the

rear

providing

a

total

range

of

up

to

30

/

1

.

The

circle

will

always

pass

through

the

origin

and

have

a

diameter

along

the

75

degree

impedance

line

equal

to

the

ohmic

reach

of

the

unit

as

expressed

by

the

following

:

(

100

)

Zi

^

Ohmic

Reach

=

Tap

Setting

(

%

)

6

Courtesy of NationalSwitchgear.com

GEK

-

1291

where

:

Z

.

.

.

.

.

=

basic

minimum

phase

-

to

-

neutral

ohmic

reach

of

the

unit

min

Directional

Action

The

OM

unit

is

carefully

adjusted

so

that

when

it

is

connected

for

zero

offset

it

will

have

correct

directional

action

under

steady

-

state

,

low

voltage

and

low

current

conditions

.

For

faults

in

the

non

-

tripping

direction

,

the

contacts

will

remain

open

at

zero

volts

between

zero

and

60

amperes

.

For

faults

in

the

tripping

direction

,

the

unit

will

close

its

contacts

between

the

current

limits

in

Table

III

for

the

three

basic

minimum

reach

settings

at

the

voltage

shown

:

TABLE

III

Basic

Min

Reach

Tap

*

*

Volts

(

Studs

17

-

18

)

Current

Range

for

Correct

Directional

Action

(

Amps

)

12

-

60

0.5

4.0

1.0

6

-

60

4.0

4

-

60

1.5

4.0

3

-

60

2.0

4.0

2

-

60

4.0

3.0

2

-

60

4.0

4.0

4.0

1

-

60

6.0

*

*

The

unit

is

set

at

the

factory

on

the

middle

tap

for

correct

directional

action

over

the

indicated

current

range

.

A

variation

of

+

10

percent

can

be

expected

on

the

values

listed

.

The

values

given

in

the

above

table

are

for

the

"

strong

spring

setting

"

.

For

the

"

weak

spring

setting

"

the

same

currents

limits

apply

at

2.0

volts

.

The

relay

is

shipped

with

"

strong

setting

"

.

If

the

"

weak

spring

setting

"

is

desired

refer

to

CONTROL

SPRING

ADJUSTMENTS

under

SERVICING

for

instruc

-

tions

.

For

performance

during

transient

low

-

voltage

conditions

,

where

the

voltage

was

normal

at

120

volts

prior

to

the

fault

,

refer

to

the

paragraph

below

on

memory

action

.

Underreach

At

reduced

voltage

the

ohmic

value

at

which

the

0

M

unit

will

operate

may

be

somewhat

lower

than

the

calculated

value

.

This

"

pullback

"

or

reduction

in

reach

is

shown

in

Figs

.

5

and

6

for

the

"

Strong

Spring

Setting

"

.

The

unit

reach

in

percent

of

setting

is

plotted

against

the

three

-

phase

fault

current

for

three

ohmic

reach

tap

settings

.

Note

that

the

fault

current

scale

changes

with

the

basic

minimum

reach

setting

.

The

0

M

unit

will

operate

for

all

points

to

the

right

of

the

curve

.

The

steady

-

state

curves

of

Figs

.

5

,

6

,

7

,

and

8

were

determined

by

tests

performed

with

no

voltage

supplied

to

the

relay

before

the

fault

was

applied

.

The

dynamic

curves

were

obtained

with

full

rated

voltage

of

120

volts

supplied

to

the

relay

before

the

fault

was

applied

.

Memory

Action

The

dynamic

curves

of

Figs

.

5

and

7

illustrate

the

effect

of

memory

action

in

the

0

M

unit

which

maintains

the

polarizing

flux

for

a

few

cycles

following

the

inception

of

the

fault

.

This

memory

action

is

particularly

effective

at

low

voltage

levels

where

it

enables

the

0

M

unit

to

operate

for

low

fault

currents

.

This

can

be

most

forcefully

illustrated

for

a

zero

voltage

fault

by

referring

to

Figs

.

5

and

7

.

A

zero

voltage

fault

must

be

right

at

the

relay

bus

and

therefore

,

to

protect

for

this

fault

,

it

is

imperative

that

the

relay

reach

zero

percent

of

its

setting

.

Fiqs

.

5

and

7

show

that

the

mho

unit

,

under

static

conditions

will

not

see

a

fault

at

zero

percent

of

the

relay

setting

regardless

of

the

tap

setting

.

However

,

under

dynamic

conditions

when

the

memory

action

is

effective

,

Fig

.

5

shows

that

the

mho

unit

with

a

three

ohm

basic

minimum

reach

and

100

percent

tap

setting

will

operate

if

I

is

greater

than

two

amperes

.

7

Courtesy of NationalSwitchgear.com

GEK

-

1291

The

memory

action

will

close

the

contact

for

only

a

short

period

of

time

and

therefore

,

memory

action

cannot

be

relied

on

if

the

tripping

is

delayed

.

When

the

relay

is

used

to

trip

the

breaker

through

the

contacts

of

a

timing

relay

the

static

characteristic

should

be

used

.

For

this

application

the

relay

is

not

required

to

operate

for

nearby

faults

and

there

will

be

sufficient

voltage

to

give

tripping

without

depending

on

memory

action

.

Transient

Overreach

Under

transient

conditions

the

OM

unit

has

a

tendancy

to

close

its

contact

momentarily

for

a

fault

impedance

greater

than

its

impedance

setting

.

This

tendency

is

called

transient

overreach

and

is

a

function

of

the

degree

of

asymmetry

in

the

fault

current

wave

,

and

the

circuit

angle

(

the

angle

of

system

from

the

point

of

the

fault

to

the

source

of

generation

)

.

For

normal

CEB

52

A

applications

,

transient

overreach

is

of

no

significance

since

the

OM

unit

does

not

perform

a

precise

measuring

function

.

Operating

Time

The

operating

time

of

the

OM

unit

is

determined

by

a

number

of

factors

such

as

the

basic

minimum

reach

setting

of

the

unit

,

fault

current

magnitude

,

ratio

of

fault

impedance

to

relay

reach

,

and

magnitude

of

relay

voltage

prior

to

the

fault

.

The

operating

time

curves

for

the

OM

unit

are

shown

in

Figs

.

9

and

10

.

All

curves

in

these

figures

are

for

the

condition

of

rated

volts

prior

to

the

fault

with

100

percent

restraint

tap

setting

.

The

curves

in

Fig

.

9

show

the

average

operating

time

of

the

unit

,

that

is

the

time

to

close

the

normally

open

contact

with

the

unit

connected

for

zero

offset

.

These

curves

also

apply

for

faults

in

the

forward

direction

if

the

unit

is

connected

for

0.5

ohm

offset

.

The

curves

in

Fig

.

10

show

opening

times

of

the

normally

closed

contact

,

with

the

unit

connected

for

0.5

ohm

offset

for

faults

in

the

direction

of

the

offset

(

reverse

)

.

It

will

be

noted

that

for

equivalent

conditions

,

that

is

for

the

same

operating

current

and

the

same

ratio

of

fault

impedance

to

reach

setting

(

or

offset

)

,

the

OM

unit

is

faster

for

faults

in

the

forward

direction

.

This

results

from

the

strong

initial

"

memory

action

"

inherent

in

the

unit

which

tends

to

sustain

the

polarizing

flux

for

a

few

cycles

following

inception

of

the

fault

.

For

faults

in

the

forward

direction

this

produces

a

higher

operating

torque

and

hence

faster

operation

.

TAPPED

AUTOTRANSFORMER

The

ohmic

reach

of

the

OM

units

may

be

adjusted

,

by

means

of

taps

on

the

two

autotransformers

.

Each

autotransformer

has

two

windings

.

One

winding

is

tapped

in

10

percent

steps

from

15

percent

to

95

per

-

cent

.

The

other

winding

is

tapped

at

0

percent

,

1

percent

,

3

percent

and

5

percent

.

The

desired

tap

setting

is

made

by

the

proper

location

of

the

leads

marked

No

.

1

and

the

jumper

connecting

the

two

windings

of

the

autotransformer

.

Note

that

the

0

-

5

percent

winding

may

be

added

or

subtracted

from

the

15

-

95

percent

winding

.

The

tap

setting

required

to

protect

a

zone

Z

ohms

long

,

where

Z

is

the

positive

phase

sequence

phase

-

to

-

neutral

impedance

expressed

in

secondary

terms

,

is

determined

by

the

following

equation

:

(

100

)

(

Min

.

Ohms

Setting

)

cos

(

0

-

0

)

Tap

Setting

=

Z

where

:

0

=

Power

factor

angle

of

fault

impedance

0

=

Angle

of

maximum

torque

of

the

unit

Example

:

TAP

SETTING

DESIRED

=

91

8

Courtesy of NationalSwitchgear.com

GEK

-

1291

Set

the

other

end

to

5

percent

.

Set

one

end

of

jumper

lead

to

95

percent

.

(

Note

the

4

percent

setting

of

the

0

-

5

percent

winding

subtracts

from

the

95

percent

settings

.

Set

No

.

1

on

1

percent

.

Example

2

:

TAP

SETTING

DESIRED

=

89

Set

the

other

end

to

1

percent

.

Set

one

end

of

jumper

lead

to

85

percent

.

(

Note

the

4

percent

setting

of

the

0

-

5

percent

winding

adds

to

the

85

percent

setting

)

.

Set

No

.

1

to

5

percent

.

BURDENS

CURRENT

CIRCUITS

The

maximum

current

burden

imposed

on

each

current

transformer

at

five

amperes

is

given

in

Table

IV

.

TABLE

IV

Rated

Frequency

VA

P

.

F

.

Ohmic

Reach

R

Watts

X

2.75

0.98

2.70

0.5

-

15

0.108

0.022

60

4.08

3.83

0.153

0.056

0.94

1

-

30

60

17.3

0.88

15.2

2

-

60

0.328

0.610

60

2.55

2.50

0.020

0.98

0.100

1

-

30

50

This

data

is

for

the

maximum

basic

reach

tap

setting

.

The

burden

on

the

two

lower

basic

reach

tap

settings

will

be

lower

.

The

above

data

includes

the

burden

of

the

transactor

used

to

offset

the

mho

characteristic

.

If

the

offset

tap

is

in

zero

the

burden

will

be

slightly

less

.

POTENTIAL

CIRCUITS

The

maximum

potential

burden

imposed

on

each

potential

transformer

at

120

volts

is

listed

in

Table

V

.

TABLE

V

Rated

Frequency

VA

Watts

Circuit

R

X

P

.

F

9.2

1540

-

j

162

9.1

Polarizing

60

0.99

8.0

4.6

0.57

1025

+

jl

460

60

Restraint

8.0

0.99

7.9

1800

-

j

175

Polarizing

50

8.2

4.7

0.58

1020

+

j

1440

Restraint

50

The

potential

burden

of

the

0

M

unit

is

maximum

when

the

restraint

tap

is

set

for

100

percent

.

The

restraint

circuit

burden

and

hence

the

total

relay

burden

will

decrease

when

the

restraint

tap

setting

is

less

than

100

percent

.

The

potential

burden

at

tap

settings

less

than

100

percent

,

can

be

calculated

from

the

following

formula

.

VA

=

(

a

+

jb

)

(

Tap

TS

,

ltt

1

ng

)

2

+

(

c

*

Jd

)

100

9

Courtesy of NationalSwitchgear.com

GEK

-

1291

The

terms

(

a

+

jb

)

and

(

c

+

jd

)

represent

the

burden

of

the

mho

unit

potential

circuits

expressed

in

watts

and

vars

with

their

taps

on

100

percent

.

The

values

of

these

terms

are

given

in

Table

VI

.

TABLE

VI

a

_

ti

a

Rated

Frequency

"

b

"

"

c

"

UdM

Watts

Vars

Watts

Vars

60

4.6

+

j

6.5

9.1

~

j

1.0

50

4.7

+

j

6.6

7.9

-

j

0.8

CONSTRUCTION

The

type

CEB

52

A

relays

are

assembled

in

a

deep

large

-

size

,

double

-

end

(

L

2

D

)

drawout

case

having

studs

at

both

ends

in

the

rear

for

external

connections

.

The

electrical

connections

between

the

relay

units

and

the

case

studs

are

made

through

stationary

molded

inner

and

outer

blocks

between

which

nests

a

re

-

movable

connecting

plug

which

completes

the

circuits

.

The

outer

blocks

attached

to

the

case

have

the

studs

for

the

external

connections

,

and

the

inner

blocks

have

the

terminals

for

the

internal

connections

.

Every

circuit

in

the

drawout

case

has

an

auxiliary

brush

,

as

shown

in

Fig

.

11

,

to

provide

adequate

overlap

when

the

connecting

plug

is

withdrawn

or

inserted

.

Some

circuits

are

equipped

with

shorting

bars

(

see

internal

connections

in

Fig

.

12

)

,

and

on

those

circuits

,

it

is

especially

important

that

the

auxi

-

liary

brush

make

contact

as

indicated

in

Fig

.

11

with

adequate

pressure

to

prevent

the

opening

of

important

interlocking

circuits

.

The

relay

mechanism

is

mounted

in

a

steel

framework

called

the

cradle

and

is

a

complete

unit

with

all

leads

terminated

at

the

inner

blocks

.

This

cradle

is

held

firmly

in

the

case

with

a

latch

at

both

top

and

bottom

and

by

a

guide

pin

at

the

back

of

the

case

.

The

connecting

plug

,

besides

making

the

electrical

connections

between

the

respective

blocks

of

the

cradle

and

case

,

also

locks

the

latch

in

place

.

The

cover

,

which

is

drawn

to

the

case

by

thumbscrews

,

holds

the

connecting

plugs

in

place

.

The

target

reset

mechanism

is

a

part

of

the

cover

assembly

.

The

relay

case

is

suitable

for

either

semiflush

mounting

on

all

panels

up

to

two

inches

thick

and

appropriate

hardware

is

available

.

However

,

panel

thickness

must

be

indicated

on

the

relay

order

to

insure

that

proper

hardware

will

be

included

.

A

separate

testing

plug

can

be

inserted

in

place

on

the

panel

either

from

its

own

source

of

current

and

voltage

,

or

from

other

sources

,

or

the

relay

can

be

drawn

out

and

replaced

by

another

which

has

been

tested

in

the

laboratory

.

Fig

.

1

shows

the

relay

removed

from

its

drawout

case

with

all

major

components

identified

.

Symbols

used

to

identify

circuit

components

are

the

same

as

those

which

appear

on

the

internal

connection

diagram

in

Fig

.

12

.

The

relay

includes

three

similar

mho

sub

-

assembly

elements

mounted

on

the

front

of

the

cradle

and

a

plate

with

transformers

and

tap

blocks

mounted

on

the

back

of

the

cradle

(

see

Fig

.

1

)

.

The

mho

sub

-

assembly

includes

the

four

pole

unit

and

the

associated

circuit

components

.

Rheostats

(

R

21

,

R

22

,

R

23

)

used

in

setting

the

angle

of

maximum

torque

and

rheostats

Rll

,

R

12

,

R

13

,

used

in

setting

the

basic

minimum

reach

can

be

adjusted

from

the

front

of

the

relay

.

The

tap

blocks

for

changing

the

basic

minimum

reach

of

the

units

and

for

selecting

the

offset

are

mounted

on

the

back

.

The

relay

must

be

removed

from

its

case

to

make

the

settings

.

RECEIVING

,

HANDLING

AND

STORAGE

These

relays

,

when

not

included

as

a

part

of

a

control

panel

,

will

be

shipped

in

cartons

designed

to

protect

them

against

damage

.

Immediately

upon

receipt

of

a

relay

,

examine

it

for

any

damage

sustained

in

transit

.

If

injury

or

damage

resulting

from

rough

handling

is

evident

,

file

a

damage

claim

at

once

with

the

transportation

company

and

promptly

notify

the

nearest

General

Electric

Company

Apparatus

Sales

Office

.

10

Courtesy of NationalSwitchgear.com