GE IAC77A User manual

GEK-34055F

TYPES

INSTRUCTIONS

TIME

OVERCURRENT

RELAYS

IAC77A

FORM

800

AND

IAC77B

FORM

800

AND

IAC78A

FORM

800

AND

IAC]8B

FORM

800

AND

GENERAL

ELECTRIC

GEK-34055

TABLE

CONTENTS

PAGE

DESCRIPTION

APPLICATION

CONSTRUCTION

RATINGS

TIME-OVERCURRENT

UNIT

INSTANTANEOUS

UNIT

TARGET

AND

SEAL-IN

UNIT

CONTACTS

BURDENS

CHARACTERISTICS

RECEIVING,

HANDLING,

AND

STORAGE

ACCEPTANCE

TESTS

VISUAL

INSPECTION

MECHANICAL

INSPECTION

ELECTRICAL

TESTS

DRAWOtJT

RELAYS

GENERAL

POWER

REQUIREMENTS

GENERAL

TIME—OVERCURRENT

UNIT

PICKUP

TEST

TIME

TEST

INSTANTANEOUS

UNIT

SETTING

THE

INSTANTANEOUS

PICK

TESTS

TARGET

AND

SEAL-IN

UNIT

PICK-UP

AND

DROPOUT

TEST

INSTALLATION

TIME-OVERCURRENT

UNIT

TARGET

AND

SEAL-IN

UNIT

INSTANTANEOUS

UNIT

PERIODIC

CHECKS

AND

ROUTINE

MAINTENANCE

TIME

OVERCURRENT

UNIT

INSTANTANEOUS

UNIT

TARGET

AND

SEAL-IN

UNIT

CONTACT

CLEANING

SYSTEM

TEST

SERVICING

TIME-OVERCIJRRENT

UNIT

TIME

TESTS

INSTANTANEOUS

UNIT

TARGET

AND

SEAL-IN

UNIT

RENEWAL

PARTS

(Cover

photo

8041299)

UNIT

GEK-34055

TIME

OVERCURRENT

RELAYS

TYPES

IAC77A,

77B,

78A,

78B

FORM

800

and

DESCRIPTION

‘ype

1AC77

and

1AC78

relays

are

single—phase,

current—operated,

.ces

with

extremely

inverse

time/current

characteristics.

They

can

utilized

protect

commercial,

industrial,

and

utility

power

distribution

systems

against

either

multi—phase

phase—to—ground

faults.

Each

relay

consists

basic

induction—disk

time—overcurrent

unit,

and

dual—rated

target/seal—in

unit,

and

may

include

hinge—

type

instantaneous—overcurrent

unit.

Both

the

time—overcurrent

unit

and

the

instantaneous

unit

are

adjustable

over

range

of about

The

available

ranges

amperes

both

units,

well

information

their

continuous

rating,

contact

rating,

and

target/seal—in

unit

tap

ratings

are

given

the

section

RATINGS.

standard

case

used

mount

each

relay.

The

outline

and

mounting

dimensions

this

case

are

shown

Figures

and

12.

The

basic

differences

between

the

relays

covered

these

instructions

are

noted

the

following

Table

TABLE

INSTANTANEOUS

CONTACT

INTERNAL

TYPE

UNIT

CIRCUITS

CONNECTIONS

IAC77A

FIGURE

IAC77B

YES

FIGURE

IAC78A

FIGURE 6

IAC78B

YES

FIGURE

These

instructions

not

purport

cover

all

details

variations

equipment nor

provide

for

every

possible

contingency

met

connection

with

installation,

operation

rnuintenunce.

Should

further

injhrmation

desired

should

particular

pro

hiems

arise

which

are

not

covered

sufficiently

for

the

purchaser’s

purposes,

the

matter

should

referred

the

General Electric

Company.

the

extent

required

the

products

described

herein

meet

applicable

ANSI,

IEEE

and

NEMA

standards;

but

such

assurance

given

with

respect

local

codes

and

ordinances

because

they

vary

greatly.

GEK-34055

APPLICATION

The

extremely

inverse

time/current

characteristics

make

the

1AC77

and

1AC78

relays

particularly

well

suited

for

the

protection

primary

distribution

circuits.

such

applications,

because

the

relay

characteristics

closely

parallel

those

the

power

fuses

normally

employed

these

circuits,

possible

obtain

selective

fault

protection

with

minimum

time

delay.

The

unique

time—current

characteristics

these

relays

also

make

them

well

suited

for

picking

cold

loads.

For

any

given

cold

load

pick

capability,

the

resulting

setting

will

provide

faster

protection

high

fault

currents

with

the

extremely

inverse

relay

than

with

less

inverse devices.

The

general

practice

use

set

three

relays

for

interphase

faults.

separate

relay,

residually

connected,

can

utilized

for

single—phase—to—ground

faults.

Use

separate

ground

relay

advantageous

because

can

adjusted

provide

sensitive

protection

ground

faults.

Typical

connections for

applying

these

relays

are

shown

Figures

and

15.

the

application

1AC77

and

IAC78

relays

with

automatic

reclosing

devices,

the

reset

time

should

considered.

The

reset

time

all

relays

covered

these

instructions

approximately

seconds

from

the

fully—closed

the

fully—open

position,

when

set

number

the

time

dial.

When

setting

these

relays

coordinate

with

“downstream’s

relays,

coordination

time

from

0.25

.40

second

generally

allowed.

These

coordination

times

include,

addition

breaker—clearing

time,

0.10

second

for

relay

overtravel

and

0.17

second

for

safety

factor.

For

example,

the

breaker-clearing

time

0.13

second

cycles)

the

coordination

time

would

0.40

second.

the

relay

time

set

test

the

current

level

question,

the

safety

factor

may

reduced

from

0.17

0.07

second.

Then

with

relay

overtravel

.10

second,

the

‘downstream”

breaker

time

cycles

(0.08

second),

minimum

0.25

second

could

allowed

for

coordination.

the

downstream

devices

are

fuses

rather

than

circuit

breakers,

then

the

maximum

clearing

time

the

fuse

should

used

and

the

time

allowed

for

breaker—clearing

time

should

omitted.

CONSTRUCTION

The

induction

unit

the

basic

unit

all

Type—IAC

relays.

Figures

and

show

the

induction

unit

mounted

the

cradle.

These

units

are

the

induction—disk

construction

type.

The

disk

actuated

wattmetric—type

current—operating

element.

This

similar

the

standard

element

used

watthour

meters,

except the

actuating

coils

above

and

below

the

operating

disk

are

connected

series.

capacitor

and

variable

resistor

connected

series

with

the

inner

coil

the

upper

laminated

structure

makes

the

phase—shifting

circuit.

The

disk

shaft

carries

the

moving

contact,

which

completes

the

trip

alarm

circuit.

The

disk

shaft

is restrained

spiral

spring

give

proper

contact—closing

GEK-34055

current,

and

its

motion

retarded

permanent

magnet

acting

the

disk

give

correct

time

delay.

There

target

and

seal—in

unit

mounted

the

front,

the

left

the

shaft

the

time—overcurrent

unit.

The

seal—in

unit

has

its

coil

series

and

its

contacts

parallel

with

the

contacts

the

time—overcurrent

unit,

such

that

when

the

induction—unit

contacts

close,

the

seal—in

unit

picks

and

seals

in.

When

the

seal—in

unit

picks

up,

raises

target

into

view,

which

latches

and

remains

exposed

until

released

pressing

button

beneath

the

lower

left

corner

the

cover.

The

instantaneous

unit

small

hinge—type

unit,

which

mounted

the

front

the

models

the

right

the

shaft

the

time—overcurrent

unit.

Its

contacts

are

normally

connected

parallel

with

the

contacts

the

time—overcurrent

unit

and

its

coil

connected

series

with

the

time—overcurrent

unit.

When

the

instantaneous unit

picks

raises

target,

which

latches

and

remains

exposed

until

released.

The

same

button

that

releases

the

target

the

seal—in

unit

also

releases

the

target

the

instantaneous

unit.

RATINGS

TIME-OVERCURRENT

UNIT

Ratings

the

time—overcurrent

unit

are

given in Table

II.

TPBLE

PICK

RANGE.

AMPERES

RELAY

FREQUENCY

MAIN

(TIME)

INSTANTANEOUS

CYCLES

UNIT

IAC77A

and

0.5

4.0

IAC78A

IAC77B

and

0.5

4.0

0.5

4.0

IAC78B

1.5

12.0

2.0

16.0

2.0

15.0 10.0

80.0

20.0

160.0

Available

taps

the

time—overcurrent

unit

are

shown on

Table

III.

TABLE

III

RANGE,

AMPERES

TAPS

AVAILABLE

(AMPERES)

0.5

4.0

0.5,

0.6,

0.7,

0.8

1.0,

1.?,

1.5,

2.0,

2.5,

3.0,

4.0

1.5

—

12.0

1.5,

2.0, 2.5,

3.0,

4.0,

5.0,

6.0,

7.0,

8.0,

10.0,

12.0

2.0

—

15.0

2.0,

2.5,

3.0,

4.0,

5.0,

6.0, 7.0,

8.0,

10.0,

12.0,

15.0

The

one—second

thermal

ratings

are

listed

Table

IV.

K-340

TABLE

TIME

OVERCURRENT

UNIT

ONE

SECOND

(AMPS)

RATING(AMPS)

0.5

4.0

125.0

15,625

1.5

12.0

260.0

67,600

2.0

15.0 260.0

67,600

For

ratings

less

than

one

second,

the

rating

may

calculated

according

the

formula

1=4

where

the

time,

seconds,

that

the

current

flows.

The

continuous

ratings

the

time—overcurrent

units

are

shown

Table

TABLE

0.5-

4.0

AMP

RANGE

TAP

0.5 0.6 0.7 0.8

1.0

1.2

1.5

2.0 2.5

3.0

4.0

[\TING

3.5 3.7

4.0

4.5

5.0

5.5

6.0

7.0

8.0

9.0

10.0

1.5-

12.0

AMP

RANGE

TAP 1.5

2.0

2.5

3.0

4.0

5.0

6.0

7.0

8.0

10.0 12.0

RATING

9.5

10.5

11.5

12.5

14.0

15.5

17.0

18.0 19.0

20.0 20.0

2.0-

5.0

AMP

RANGE

TAP

2.0 2.5

3.0

4.0

6.0

7.0 8.0 10.0

12.0

15.0

RATING

10.0 11.0

12.0

13.0 15.0 17.0 18.0

19.0

20.0

INSTANTANEOUS

UNIT

The

instantaneous

unit

has

double—wound

coil

for

operation

either

one

two

ranges.

Any

setting

obtained

the

lower

range

(series

connected)

doubled,

within

±3%,

when

the

unit

connected

for

high—range

operation

(parallel

connected).

K-340

The

instantaneous

unit

has

continuous

rating

1.5

times

minimum

setting

amperes,

whichever

smaller.

Example:

The

2.0—16.0

ampere

instantaneous

unit,

when

set

the

low

range

(2.0—

8.0

amperes)

has

continuous

rating

3.0

amperes,

and

when

connected

for

high-range

operation

(4.0—16.0

amperes)

has

continuous

rating

6.0 amperes.

The

continuous

and

one—second

ratings

for

the

instantaneous

unit

are

shown

in Table

VI.

TABLE

RANGE

CONNECT—

CONTINUOUS

ONE

IONS

RATING

SECOND

0.5

4.0 0.5

—

2.0

0.15 25.0

625

1.0

4.0

1.5 50.0

2,500

2.0

16.0

2.0

8.0

3.0

130.0

16,900

4.0

16.0

6.0

260.0 67,600

10.0

80.0

10.0

40.0

15.0

400.0

160,000

20.0

80.0

25.0

600.0

360,000

20.0

160.0

20.0

80.0

25.0

600.0

360,000

40.0

160.0

25.0 600.0

360,000

Higher

currents

may

applied

for

shorter

lengths

time

accordance

with

the

formula

where

the

time,

seconds,

that

the

current

flows.

Series

connected,

Parallel

connected

TARGET

AND

SEAL-IN

UNIT

Ratings

for

the

target

seal—in

unit

are

shown

in Table

VII.

TABLE

VII

TAP

0.2 2.0

D.C.

Resistance

10%

(ohms)

0.13

MIN.

Operating

(amperes)

25%

0.2 2.0

Carry

Continuously

(amperes)

0.3

3.0

Carry

Amps

for

(sec.)

0.03

4.0

Carry

Amps

for

(sec.)

0.25

30.0

Impedance

(ohms)

52.0

0.53

GEK-34055

the

tripping

current

exceeds

amperes,

auxiliary

relay

should

used,

the

connections

being

such

that

the

tripping

current

does

not

pass

through

the

contacts

the

target

and

seal—in

coils

the

protective

relay.

CONTACTS

The

current—closing

rating

the

contacts

amperes

for

voltages

not

exceeding

250

volts.

The

current—carrying

rating

limited

the

ratings

the

seal—in

unit.

BURDENS

Burdens

for

the

time—overcurrent

unit

are

given

Table

VIII.

TABLE

VIII

BURDENS

MIN.

BURDENS IN

PICKUP

MIN.

TAP

OHMS

(1)

V.A.

AMPS

RANGE

MIN.

20.0

CALCULATED

FROM

TAP

TIMESTIMESTIMES

IMPEDANCE

MIN.

PICK-

PICK- PICK-

PICKUP

(121)

tip

LIP

0.5

0.4

0.5

0.80

1.38 1.60 1.60 1.60 1.60

1.5

12.0

1.5 0.085

.147

0.17 0.17

0.17

4.25

2.0

15.0

2.0

0.05 0.086

0.099

0.10

0.10 0.10

2.5

NOTE:

The

impedance

values

given

are

those

for

the

minimum

tap

each

relay.

The

impedance

for

other taps

pick—up

current

(tap

rating)

varies

inversely

(approximately)

the square

the

tap

rating.

For

example,

for

relay

with 0.5

—

4.0

amp

range,

the

impedance

the

0.5

amp

tap

given

1.60

ohms.

The

impedance

the

2.0

amp

tap

2.0

amperes

(.5/2)2

1.6

or 0.10

ohm.

GEK-34055

The

instantaneous

unit

burdens

are

listed

Table

IX.

TABLE

BURDENS

MIN.

BURDENS

RANGE

PICKUP

MIN.

TAP

OHMS

(Z)

RELAYS

TIONS

AMPS

20.0

V.A.

5AMPS

ONLY

OHMS OHMS OHMS

TIMES

CALCULATED

FROM

(AMPS)

PICK

PICK PICK

IMPEDANCE

MIN.

PICKUP

(I?Z)

5-4

LOW

0.5

12.1 11.5 17.1

9.6 8.7

8.2

427.5

HIGH

1.0 3.18

2.87

4.28

2.40

2.18

2.04

107.0

0-16

LOW

2.0

0.76 0.72

1.05

O.5

0.53

0.50

26.25

HIGH

4.0

0.189

0.180

0.261

0.147

0.133

0.125

6.63

0-80

LOW

10.0

0.042 0.029 0.051 0.029

0.026

0.024 1.28

HIGH

20.0

0.010

0.007

0.013 0.007

0.001

0.006

0.33

0-160

LOW

20.0

0.015

0.008

0.017

0.010 0.009 0.008

0.43

HIGH

40.0

0.004

0.002 0.004 0.002

0.002

0.10

Low

means

two

windings

connected in

series.

High

means

two

windings

connected

parallel.

See

Internal—Connections

diagram

for

additional

information.

CHARACTERISTICS

Pickup

these

relays

defined

the

current

required

the

contacts

from

the

0.5

time—dial

position.

The

pickup

value

the

1AC77

relays

within

the

tap

value.

The

setting

the

time

dial

determines

the

length

time

the

unit

requires

its

contacts

when

the

current

reaches

the

predetermined

value.

The

contacts

are

just

closed

when

the

dial

set at

zero.

When

the

dial

set

10,

the

disk

must

travel

the

maximum

distance

the

contacts;

this

gives

the

maximum

time

setting.

The

unit

resets

85%

the

minimum

closing

value

current.

Figure

shows

the

50—Hz

and

Figure

shows

the

60—Hz

Time/Current

Characteristics

for

Relay

types

1AC77

and

1AC78.

The

time

reset

to the

time-dial

position

when

the

current

reduced

zero

approximately

seconds.

The

time/current

curve

for

the

instantaneous

unit

shown

Figure

RECEIVING,

HANDLING,

AND

STORAGE

These

relays,

when

not

included

part

control

panel,

will

shipped

cartons

designed

protect

them

against

damage.

Immediately

upon

receipt

relay,

examine

for

any

damage

GEK-34055

sustained

transit.

injury

damage

resulting

from

rough

handling

evident,

file

damage

claim

once

with

the

transportation

company

and

promptly

notify

the

nearest

General

Electric

Sales

Office.

Reasonable

care

should

exercised

unpacking

the

relay

order

that

none

the

parts

are

injured

nor

the

adjustments

disturbed.

the

relays

are

not

installed

immediately,

they

should

stored

their

original

cartons

place

that

free

from

moisture,

dust,

and

metallic

chips.

Foreign

matter

collected

the

outside,

the case

may

find

its

way

inside

when

the

cover

removed

and

cause

trouble

the

operation

the

relay.

ACCEPTANCE

TESTS

Immediately

upon

receipt

the

relay,

INSPECTION

AND

ACCEPTANCE

TEST

should

made

make

sure

that

damage

has

been

sustained

shipment

and

that

the

relay

calibrations

have

not

been

disturbed.

the

examination

test

indicates

that

readjustment

necessary,

refer

to the

section

SERVICING.

These

tests

may

performed as

part

the

installation

or as

acceptance

tests,

the

discretion

the

user.

Since

most

operating

companies use

different

procedures

for

acceptance

and

for

installation

tests,

the

following

section

includes

all

applicable

tests

that

may

performed

these

relays.

VISUAL

INSPECTION

Check

the

nameplate

stamping

make

sure

that

the

model

number

and

rating

the

relay

agree

with

the

requisition.

Remove

the

relay

from

its

case

and

check

that

there

are

broken

cracked

molded

parts

other

signs

physical

damage, and

that

all

the

screws

are

tight.

MECHANICAL

INSPECTION

There

should

noticeable

friction

when

the

disk

rotated

slowly

clockwise.

The

disk

should

return

itself

its

rest

position.

Make

sure

the

control

spring

not deformed,

nor

its

convolutions

tangled

touching.

The

armature

and

contacts

the

seal—in

unit,

well

the

armature

and

contacts

the

instantaneous

unit,

should

move

freely

when

operated

hand;

there

should

least

1/32”

wipe

the

seal—in

contacts.

The

targets

the

seal—in

unit

and

the

instantaneous

unit

must

come

into

view

and

latch

when

the

armatures

are

operated

hand,

and

should

unlatch

when

the

target

release

lever

operated.

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