GE 12IAC8OL User manual

INSTRUCTIONS
Insert
Booklet-
GEH-1788
TIME
OVERCURRENT
RELAY
TYPE
TAC
MODEL
12IAC8OL(-)A
INTRODUCTION
This
supplement
in
conjunction
with
GEH—1788
forms
the
instructions
for
relay
model
12IAC8OL(-)A.
DESCRIPTION
Relay
model
12IAC8OL(-)A
consists
of
a
single
IAC
type
time
overcurrent
unit
with
a
seal—in
unit
mounted
in
a
small
single
ended
(Si)
case.
This
relay
is
similar
to
model
121AC53A(-)A
described
in
GEK-1788
except:
1)
The
internal
connections
are
as
shown
in
figure
1
of
this
supplement.
2)
The
induction
unit
uses
wound
shading
coils
on
the
U-magnet
to
provide torque
control.
This
control
circuit
(connected
to
studs
3
and
4)
must
be
completed
in
order
that
there
be
a
phase
displace
ment
in
flux
to
rotate
the
disk.
When
the
shading
coil
circuit
is
completed,
torque
can
be
developed
on
the
induction
disk
and the
unit
will
operate
on
overcurrent.
When
the
shading
coil
circuit
is
open,
the
unit
will
not
operate
at current
levels
up
to
20
times
tap
value.
The
time
current
curves,
burdens
and
ratings
of
this
relay
are
as
given
in
GEH-1788
for
model
121AC53A(-)A.
Those
Instructions
do
not
purport
to cover
all
detafle
or
variation.
in
equip..nt
nor to
provide
for
every
possible
contingency
to
be
met in
connection
with
inatal3atioq,
operation
or
.aintenanc..
Should
further
information
be
desired
or
should
particular
probls
arise
which
are
not
covered
•ufficiently
for
the
purchaser’s
puro.ea,
the
matter
should
be
referred
to
the
General
Liectric
Company.
POWER
SYSTEMS
MANAGEMENT
DEPARTMENT
GENERAL•
ELECTRIC

GEK- 27870
*
=
SHORT
FINGERS
CONTROL
WINDINGS
C)
6
FIG.
1
(0226A7211-0)
INTERNAL
COKNECTIONS
DIAGRAM FOR THE
IACBOL(-)A
RELAY
(FRONT
VIEW)
GENERAL
ELECTRIC
CO..
POWER
SYSTEMS
MANAGEMENT BUSINESS
DEPT.,
MALVERN,
PA.
19355
SEAL—IN
1
3
24
8-70

INSTRUCTIONS
GEH-1
788L
TYPES
TIME
OVERCURRENT
RELAYS
GENERAL
ELECTRIC
IAC53A
IAC53B
IAC53C
IA
C5
3 R
IAC54A
IAC54B

c’1
c..J
c..1
Di
LL
cS-i
LC)
C’,
0
>
0
C-,
GEH-1788
Tvne
IAC
Time
Overcurrent
Relay
TOP
PIVOT
TAP PLUG
SEAL-IN
UNIT
HOLDING
(0I
L
SEAL-
IN
TARGET
SEAL-IN
--
UNIT
STATIONARY
CONTACT,
FT
S[AL
N
UNIT
STATIONARY
CO
N
TA (.T
RIGHT
SEAL
IN
MOVING
CON
TACT
AC
3EMBLY
TAP
BLOCK
--TIMF
DIAL
DISK
SHAFT
MAIN
MOVING
CONTACT
M A
N
STA’
IDNARY
ROUGH
AND
CONTACT
ASS
C
MB
L
Y
MAGNET
0151<
(ii
Si,p,
—
-‘p
‘4
Fiq.
I
The
Induction
Unit
for
Type
IAC
Relays
(Front
View)
DISK
AND
SHAFT
—
JEWEL
SCREW
Fin.
2
The
Induction
Unit
for
Type
IAC
Relays (Rear
View)
2

TIME
OVERCURRENT
RELAYS
TYPE
IAC
INTRODUCTION
The
Types
1AC53
and
1AC54
relays are
time
overcurrent
relays
with
a
very-inverse
time
char
acteristic.
They
are
employed
to
protect
against
overcurrent
on
single-phase
and poly-phase
circuits.
The
various
relays
described
in
this
instruction
book
differ
in
the
number
of
circuits
they
close,
and if
an
instantaneous
unit
and/or
an
a-c
tripping
unit
is
included.
These
relays
consist
of
an induction unit
or
an
induction
unit
with
an
instantaneous
unit
which
per-
mits
instantaneous
tripping
for
exteremely
high
cur
rents,
or
an
induction
unitwithana-c
tripping
unit for
use
where
d-c
power
is unavailable or
a-c
tripping
is
preferred.
Since
practically
all
Type
IAC
relays
are
composed
of
various
combinations
of
the
above
(that
is,
the
induction
unit, the
instantaneous
unit
and the
a-c
tripping
unit),
they
are,
for convenience,
describ
ed
separately
in
the
following
text.
The
above
table
indicates
the
units
comprising
each
type
and
also
lists
the
internal
connections
and
outline
andpanel
drilling
diagrams.
INDUCTION UNIT
INTRODUCTION
The
induction unit
is
the
basic
unit
in
all
Type
TAC
relays.
Figs.
1
and
2
show
the
induction
unit
mounted
in
the
cradle.
These
units
are
of
the
induc
tion-disk
construction
type.
Thediskisactuatedby
a
current
operating
coil
on
a
laminated
U-magnet.
The
disk
shaft
carries
the
moving
contact
which
completes
the
alarm
or
trip
circuit
when
it
touches
the
station
ary
contact or contacts.
The
disk
shaft
is
restrained
by
a
spiral
spring
to give
the
proper
contact-closing
current
and
its
motion
is
retarded
by
a
permanent
magnet
acting
on the
disk
to give
the
correct
time
delay.
There
is a
seal-in
unit
mounted
on
the
front
to
the
left
of
the
shaft.
This
unit
has
its
coil
in
series
and
its contacts
in
parallel
with the main
contacts
such
that
when
the main
contacts-close
the
seal-in
unit
picks
up
and
seals
in.
When
the
seal-in
unit
picks
up, it
raises
a
target
into
view
which
latches
up
and
remains
exposed until
released
by
pressing
a
button
beneath
the
lower
left
corner
of the
cover.
APPLICATION
The
induction unit
is
the
main
unit
in
all
Type
IAC
relays,
supplying
the
very
inverse
time
delay
characteristics
of
the
relay
and
soundingan
alarm
or
tripping
the
breakers
for overload
currents
which
cause
it
to close its contacts.
OPERATING
CHARACTERISTICS
The
induction
unit
may
have
one
or two
circuit-
closing
contacts
which
close
as
the
current increases
to
the pick-up
value
as set on the
tap
block. The
time
delay
in closing
the
contacts
is determined
by
the
setting
of the
time
dial
(Fig.
1).
The
time-cur
rent
characteristics
are
shown
in
Fig.
3.
RATINGS
The
induction
unit
is
designed
to use
any
one
of
four
operating
coils,
each
having
a
different
com
bination
of
taps
as
follows,
4,5,6,7,8,10,12,
and
16
amperes;
1.5,2.0,
2.5,
3.0, 4.0,
5.0
and
6.0
amperes;
0.5, 0.6,
0.8,
1.0,
1.2,
1.5
and
2.0
amperes;
0.1,
0.12,
0.16,
0.2,
0.24,
0.3
and
0.4
amperes.
T
Contact
Instan.
A-C
Trip
Induc.
Outline
mt.
ype
Circuits
Unit
Unit
Unit
&P.
D.
Conn.
IAC53A(-)A
One
No
No
One
Fig.
20
Fig.
12
IAC53B(-)A
One
Yes
No
One
Fig.
20
Fig.
13
IAC53C(-)A
One
No
Yes
On
Fin.
20
Fig.
14
iAC53R(-)A
One
Yes
Yes
One
Fig.
20
Fig.
15
IAC54A(-)A Two
No
No
One
Fig.
20
Fig.
16
1AC54B(-)A
Two
Yes
No
One
‘Fig.
20
Fig.
17
Shove
instructions
do
not
purport
to
cover
al.!
details
or
variations
in
equipment
nor
to
provide
for
n’Jer
posszble
contingency to
be
met
in
connect
ion with
installation,
operation
or
rrintenance.
Should
rurt;2-O-
information
he
des;rcd
or
should
particular
problems
arise
which
are
not
covered
sufficiently
for
the
pur.:lianer
‘s
purposes,
the
matter
should
be
referred
to
the General
Electric
Company.
To
Civ
Cxtent
requlred
the
products
described herein
meet
applicable
ANSI,
IEEE
and
NEMA
standards; but
no
such
ssura.nce
is
qiven
with
respect
to
local
codes
and
ordinances
because
they
vary
greatly.
3

GEH-1788
Type
[AC
Time
Overcurrent
Relay
:
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Figure
3 (0888e0270
[3])
Time-Current
Curves
for
Type
IAC
Relays
with
Very-Inverse-Time
Characteristics
I
$
44
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III
MULTIPLES
OF RELAY
TAP SETTING
I
I I
fiiiij
4

Type
IAC
Time Overcurrent
Relay
GEH-1788
CALIBRATION
PLATE
ADJUSTABLE
I-.---- POLE PIECE
MS
TA
N
TA N
EDUS
UNIT
OPERATING
COIL
TARGET
STATIONARY
[
CONTACTS
MOVING
CONTACT
ASSEMBLY
CONTACTS
SHORTING
COIL
BURDENS
The
current-closing rating of the
contacts
is
30
amperes
for voltages
not
exceeding
250 volts.
The
current-carrying
ratings
are
affected
by
the
selection
of
the
tap
on
the target
and seal-in
coil
as
indicated
in the
following
table:
Amperes, a-c
or d-c
Function
2-Amp
Tap
0.2
Amp
Tap
Tripping
Duty
30
5
Carry
Continuously
3
0.3
Operating
Range
2-30
0.2-2
Resistance
0.13
7
Impedance
at 60
cy
0.53
52
If
the
tripping
current
exceeds
30 amperes
an
aaxiliary
relay
should be
used, the
connections
being
such
that the
tripping
current
does
not pass
through
the
contacts
or
the target
and
seal-in coils
of
the
protective
relay.
Burdens
for the
standard coils
are given
in the
following
table. These
are
calculated
burdens
at
five
amperes
based
on burden
of
minimum
tap.
Volt-ampere
burdens
for
the lowest
tap
on
any
of the
three coils
can
be determined
for any
value
of
current,
up
to
20 times
tap setting,
from
Fig.
6.
Coil
I
Volt Imp.
Amps
Freq.
Tap
Amps
Amps Ohms
PF
4-16
60
4
5
2.0
0.08
0.50
50
4
5
1.7
0.07
0.50
25
4 5
1.3
0.05
0.61
1.5-6
60 1.5
5
14.5
0.58
0.42
50 1.5
5
12.0
0.48
0.42
25
1.5
5
9.0
0.36
0.55
0.5-2
60
0.5
5
105.0
4.20
0.35
50
0.5
5
86.0
3.45
0.34
25
0.5
5
82.0 3.28
0.55
60
0.1
5
3050
122
0.38
0.1-0.4
5tJ
0.1
5
2546
102
0.36
INTRODUCTION
INSTANTANEOUS
UNIT
The
instantaneous
unit
is
a small
instantaneous
hinge-type
unit which
may be
mounted
on the
right
front
side
of the
induction
unit
(See
Fig.
4).
Its
contacts
are
normally
connected
in parallel
with
the
contacts
of the
main
unit. Its
coil
is connected
in
series
with the
operating
coil
of the main
unit.
When
the
current
reaches
a predetermined
value,
the
instantaneous
unit
operates,
closing
the
contact
circuit
and
raising
its
target
into
view.
The
target
latches
in
the exposed
position
until
released
by
pressing
the
button
beneath
the
lower
left-hand
corner
of the
relay
cover.
1•-
C’4
C.,’
cc
0,
LL
c..J
C.,’
cc
MAIN
COIL
A
-C
TRIPPING
UNIT
U-
Fig.
L
Type
AC
Relay with
an
Instantaneous
Unit
(Front View)
Fig. 5
Type IAC
Relay
with an
A—C Trip
Unit
(Rear View)
5

GEH-1788
Type
IAC
Time
Overcurrent
Relay
0
24
6
8
10
12
14
16
18
20
MULTIPLES
OF MINIMUM
SATURATION
CURVES
FOR
INDUCTION
UNITS
ON
TYPE
IAC
RELAYS
PIC1(—UP
CURRENT
LOWEST
TAPS
OF
VERY
INVERSE
Fig.
6
Saturation
Curves
for Lowest
Taps
of
tre
Induction
Unit
of
Type
IAC
Re’ays
with
Very—Inverse-Time
Character
i
stics
26
24
22
20
16
14
12
10
8
6
4
2
0
V
0
L
T
A
G
E
z
V
V
;
/Ez
—--
-
-
iEEEEz
—--------
6
0r.,
5Q,,,
25.
6O
50
25
50.-s.,
25
TA
P
RANGE
0.5—2.0
AMPS.
TAP
RANGE
1.5—6.0
AMPS.
-
TAP
.RANGE
4—16
AMPS.
V..
C
C
0
‘a
U-
6

Type
IAC
Time
Overcurrent
Relay
(JEH-1788
0.030
0.025
0.
20
0.015
0.
010
0.005
10
Fig.
7A
(K-6306872
[5).
Time-Current
Characteristics
for Original
Instantaneous
Unit
,I
$I94C
RATD
TMTIRJS
IJIT
Fig. 7B
(0208A869
5-1)
Time-Current
Characteristics
for
the Hi-G”
Unit
c)
LI
Cr,
LI
L)
0
—
&
OPERATING
TIME
—
c—
RANGE
FOR
ANY
PICKUP
SETTING
—
0
0
1
2
3
4
5
6
M.JLTIPLES
OF
PICK—UP
7
89
aILTIPiF
OF
PICOOP
.7

GEH-1788 Type
IAC Time
Overcurrent
Relay
APPLICATION
rhe
instantaneous
unit
is
used
on
certain
Type
IAC relay
models
to
provide
instantaneous tripping
for
current
exceeding
a
predetermined
value.
OPERATING
CHARACTERISTICS
*
The
instantaneous
unit
operates
over
a
four—
to—one
range
and has
its
calibration
stamped
on
a
scale
mounted
beside
the
adjustable
pole piece.
Time—current characteristics
are shown
in
Fig.
7A
for
the
instantaneous
unit used
before
1977.
In 1977 the
instantaneous
unit
was modified to
make it
have
a
higher
seismic
rating. The new
instantaneous
unit
can
be
identified by
the
mark
ing
“Hi—C”
moulded
into the front moulding just
above
the target
windows.
The
time—current
characteristic
for
the
“Hi—C”
unit
is
shown
in
Fig. 7B.
RATINGS
The instantaneous
unit
is
designed
to
use
the
coils
listed
below;
Coil
Freq
Amp
Volt-
Imp.
P.F.
Amp
Ohms
0.5-2
60
- 5
360
14.4
0.74
1-4
60
90
3.6
0.77
2—8
60
5
22.5
0.90
0.83
25
5
8.0
0.32 0.83
4-16
60
5
5.63
0.225
0.87
50
4.77 0.191
0.87
40
5
3.93
0.157
0.88
25
5
2.37 0.095
0.88
7—28
60
5
1.88
0.067
0.88
10-40
60
5
0.83
0.033
0.95
50
5
0.80
0.032
0.95
25
5
0.68 0.027
0.98
20-80
60
5
0.20
0.008
0.95
50
I
5
0.20 0.008
0.95
25
5
0.18
0.007
0.98
A-C
TRIPPING
UNIT
INTRODUCTION
The a-c
tripping
unit is
aType
REA
relay
unit
designed
to
energize
a
circuit-breaker
trip coil
from
its
associated
current
transformer
upon
the
operation
of
the
main
unit
of
the
Type TAC
relay.
It
transfers
the current
from
the
secondary
of
the
current
transformer
into
the
trip
coil
and removes
the
current
from
the
trip coilwhen
the
breaker
trips.
The tripping
unit
is
mounted
on
the
rear
of
the
frame
opposite
the tapped
operating
coil
of
the
in
duction unit
(see
Fig. 5).
The
operation
of
this unit
is
illustrated
in
FIg. 11. The
secondary
current
circulates
through the
Induction
unit
current
coil
and
the
main
coil
of
the
Type REA
auxiliary
tripping
unit,
returning
through
the
Type
REA
contacts
to the
cur
rent transformer.
Normally,
most
of
the flux
gener
ated
by
the
main
Type
REA
coil
passes
through
the
upper limb
of
the magnetic
structure
and
holds
the
armature
firmly
against
this
limb.
When
the
contacts
of
the
induction unit
close,
the
shorting
coil of
the
Type
REA
unit is
short-circuited
and
current
flows
in
this
coil
by
transformer
action, causing
a
redis
tribution
of
flux
which
actuates
the
armature
and the
Type
REA
contacts.
The
opening
of
the
Type
REA
contacts
causes
the
secondary
current
to
flow
through
the
trip
coil
which
trips
the
breaker.
8
*
Indicates
revision

Type
IAC
Time
Overcurrent
Relay
GEH-1788
Figure
8
(K-6315667
[2])
External
Connections
of
Three
Type
IAC53A
Relays
Used
for
Phase-to-
Phase
and Ground
Overcurrent
Protection
of
a
3-Phase
Circuit
Figure
9. (K6375668-1)
External
Connections
of
Three
Type
IAC53A
Relays
used
in
Conjunction
with
Tripping
Reactors for Protection
of
a
3-Phase
Circuit
Device
Function
Numbers for
Use
with
ALL
External
Diagrams
Instantaneous
Unit
Overcurrent
Relay,
Type
IAC
Ground
Overcurrent
Relay,
Type
IAC
Power
Circuit
Breaker
Seal-in
Unit,
with
Target
Trip
Coil
Auxiliary
Contact,
closed
when
breaker
closes
Figure
10.
(K-6375669-6)
External
Connections
of
Three
Type
IAC53R
Relays
Used
For 3-Phase
Circuit
Protection
3
50
J
51
51N
52
SI
TC
A
POC
9

GH-11
Type
TAC
‘time
Overcurrent
Relay
APPLICATION
The
a-c
tripping
unit
is
used
in
Type
[AC
relays
where
a
reliable
direct-current
tripping
source
is
not
available
and
it is
necessary
to
trip
the
breaker
from
the
current-transformer
secondary.
RATINGS
The
a-c
tripping
unit
has
a
continuous
rating
of
five amperes
but
will
operate
on
a
minimum
current
of
3.5
amperes.
It
should
be
used
with
three-
ampere
trip
coils.
The
contacts
of
these
units will
transfer
current-transformer
secondary
current
up
to
100
amperes.
For
applications
where
the
sec
ondary
current
exceeds
100
amperes,
the Type
REA11B
relay,
which has
contacts
rated
200
am
peres,
can
be
used
in conjunction
with
Type
IAC
overcurrent
relays.
The
Type
REA11B
is
not
mounted
inside
the
Type
IAC
case.
SURDENS
Burdens
of
the Type
REA
unit
are
given
in the
following
table:
Impedance
PF
Amperes
Frequency
Amps
in
Ohms
60
5
0.49
0.80
12.2
50
5
0.33
0.80
8.3
25
5
0.23
0.62
5.8
Fig.
II
Diagram
Illustrating
Operation
of
Type
lAG
Relays
having
an
A—C
Tripping
Unit
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
andpromptly
notify the
nearest
General
Electric
Apparatus
Sales
Office.
Reasonable
care
should
be
exercised
in
unpack-
ing
the
relay
in
order
that
none
of
the
parts
are
injured or
the
adjustments disturbed.
If
the
relays
are
not
to
be
installed
immed
iately,
they
should
be
stored
in
their
original
car
tons
in
a
place
that
is
free
from
moisture,
dust
and
metallic
chips.
Foreign
matter
collected
on
the
outside
of
the
case
may
find
its
way
inside
when
the
cover
is
removed
and
cause
trouble
in
the
operation
of
the
relay.
iNSTALLATION
LOCATION
The
location
should
be
clean
and
dry,
free
from
dust
and
excessive
vibration,
and
well
lighted
to
facilitate
inspection
and
testing.
MOUNTiNG
*
The
reLay
should
be
mounted
on
a
vertical
surface.
The
outline
and
panel
diagram
is
shown
in
Fig.
20.
CONNECTIONS
The internal
connection
diagrams
for
the
various
relay
types
are
shown
in
Figs.
12
to
17
inclusive.
Typical
wiring
diagrams
are
given
in
Figs.
8
to
10
inclusive.
One
of
the
mounting
studs or
screws
should
be
permanently
grounded
by
a
conductor
not
less
than
No.
12
B
&
S
gage
copper
wire
or
its
equivalent.
INSPECTION
At the
time
of
installation,
the
relay
should
be
inspected
f6r
tarnished
contacts,
loose
screws,
or
other
imperfections.
If
any
trouble
is
found,
it
should
be
corrected
in
the
manner
desctibed
under
MAINTENANCE.
IL
AC
TRIP
UNIt
NOPI.’ALLY
CLOCE
[)
CONTACJ
S
AC
TRIP
UNIT
SNORTING
COIL
AC
TRIP
UNI
I
EAIN
COIL
(‘J
LS)
C
10
*
Indicates
Revision

C
0
‘C
0’
0
1’
Type
IAC
Time
Overcurrent
Relay
GEH-1788
Fig.
12 Internal
Connections
for
Type
IAC53A
Relay
(Front
View)
,
Fig.
(K-6209660-7)
Internal
Connections
For
Type
IAC53C
Relay
(Front
View)
a.
a.
L1
Fig.
13 Internal
Connections
for
Type
1AC538
Relay
(Front
View)
*
Fig.
15
Internal
Connections
for
Type
IAC5
Relay
(Front
View)
A—C
iRI
UN
I
I
NSTANT
T
U,
0’
0
‘C
c•4
a.
U-
SEAL—
N
UN I
I
NOUCT
ON
SEAL—IN
UNIT
IN5TAN
UN
I I
/11
13
5
2
6
1
5
6
ZSHORT
FINGER
SHORT
FINGER
SEA
Li
N
UNIT
INDUCT
I
UN
I
T
INDUCTION
UN
3
6
*
1ndicatts
Revision
11

GEH-l,
‘rype TAG
Time
Overcurrent
Melay
NUIJCI
ION
UN
-n
=
SHORT FINGER
a.
Fig.
17
Internal
Connections
for
Type
IAC5L4B
current circuits
and
other
circuits
with
shorting
bars
that
the
auxiliary
brush
be
bent
high
enough
to
engage
the
connecting
plug
or
test
plug
before
the
main
brushes
do.
This will
prevent
CT
sec
ondary
circuits
from
being
opened.
!•1
L0
CD
SEAL—IN
UN
I
1
-Ti
-‘-a
a.
r.j
aD
0’
0’
C-i
CD
NSTANT.
IN
II
SI
AL
— I
N
a
6
=
SH(IQI
FINGEA
Fig. 16
InternalConnections
for
Type
IACSLIA
CAUTION:
Every
circuit
in
the
drawout
case
has
an
auxiliary
brush.
It
is
especially
important
on
9
10
CONNECTING PLUG
MAIN
BRUSH CONNECTING
BLOCK
.i1
AUXILIARY
BRUSH---
TERMINAL
BLOCK\
SHORTING
BAR—
NOTE AFTER ENGAGING
AUXILIARY
BRUSH,
CONNECTING
PLUG
TRAVELS
)/4
INCH
BEFORE
ENGAGING
THE
MAIN BRUSH
ON
THE
TERMINAL BLOCK
Fig.
18
Cutaway
of
Drawout
Case
Showing
Position
of
Auxiliary
Brush
CD
U,
Ci)
CD
12

Type
JAC
Time
Overcurrent
Relay
GEH-
1788
ADJUSTMENTS
TARGET
AND
SEAL-IN
UNIT
For
trip
coils
operating
on
currents
ranging
from
0.2
to
2.0
amperes
at
the minimum
control
voltage,
set
the target
and
seal-in
tap
screw
in
the
0.2-ampere
tap.
For
trip
coils
operating
on currents
ranging
from
2
to
30
amperes
at
the
minimum
control
voltage
place
the
tap
screw
in
the
2-ampere
tap.
The
tap
screw
is the
screw
holding
the
right-
hand
stationary
contact
of the
seal-in
unit.
To
change
the
tap
setting,
first
remove
the
connecting
plug.
Then,
take
a
screw
from
the
left-hand
stationary
contact
and
place
it
in the
desired
tap.
Next,
remove
the
screw
from
the
other
tap and
place
it
in
the
left-hand contact.
This
procedure
is
necessary
to
prevent
the
right-hand
stationary
contact
from
getting
out
of
adjustment.
Screws
should
not
be
in
both
taps
at
the
same
time.
INDUCTION
UNIT
CURRENT SETTING
The
current
at
which
the
contacts operate
may
be
changed
by
changing
the position
of the
tap
plug
in
the tap
block
at
the top
of
the
relay.
Screw
the
tap
plug
firmly
into
the tap
marked
for
the
desired
current
(below
which
the
unit
is
not
to operate).
When
changing
the
current
setting
of
the
unit,
remove
the
connecting
plug
to
short-circuit
the
current-transformer
secondary
circuit.
Next,
screw
the
tap
plug
into
tap
marked
for
the desired
current
and then
replace
the
connecting
plug.
The
pickup
of the
unit
for
any
current
tap
is
adjusted
by means
of
a
spring-adjusting
ring.
The
ring
may
be
turned
by
inserting
a
tool
in the
notches
around
the edge.
By
turning
the
ring,
the
operating
current
of
the
unit
may
be brought
into
agreement
with
the
tap
setting
employed,
if
for
some
reason,
this
adjustment
has
been
disturbed.
This
adjustment
also
permits
any
desired
setting
intermediate
be
tween the
various
tap
settings
to be
obtained.
The
unit
is
adjusted
at
the
factory
to
close
its
contacts
from
any
time-dial
position
at
a
minimum
current
within
five
per
cent
of
the
tap plug
setting.
The
unit
resets
at
90 per
cent
of the
minimum
closing
value.
TIME
SETTING
The
setting
of
the
time
dial
determines
the
length
of
time
the
unit requires
to
close
its
con
tacts
when
the
current reaches
the
predetermined
value.
The
contacts
are
just
closed
when the
dial
is
set
on
0. When
the
dial
is
set on
10, the
disk
must
travel
the
maximum
amount
to
close
the
contacts
and
therefore
this
setting
gives
the
max
Imum
time
setting.
The
primary
adjustment
for the
time
of oper
ation
of the
unit
is
made
by means
of the
time
dial.
However,
further
adjustment
is
obtained
by
moving
the
permanent
magnet
along
its supporting
shelf;
moving
the
magnet toward
the
main
shaft
of
the
unit
decreases
the
time,
while
moving
It
away
increases
the
time.
If
selective
action
of two
or
more
relays
is
required,
determine
the
maximum
possible
short-
circuit
current
of the
line
and
then
choose
a
time
value
for each
relay
that differs
sufficiently
to
insure
the
proper
sequence
in
the
operation
of
the
several
circuit
breakers.
Allowance
must
be
made
for
the
time
involved
in opening
each
breaker
after
the
relay
contacts
close.
For this
reason,
unless
the
circuit
time
of
operation
is
known with
accuracy,
there
should
be
a
dhfference
of about
0.5
second
(at the
maximum
current)
between
relays
whose
operation
is to
be selective.
EXAMPLE
OF
SETTING
The
time
and
current
settings
of the
over-
current
unit can
be
made
easily
and
quickly.
Each
time
value
shown
in Fig.
3
indicates
the
time
required
for
the
contacts
to close
with
a
particular
time-dial
setting
when the
current
Is a prescribed
number
of
times
the
current-tap
setting.
In order
to
secure
any
of the
particular
time-current
settings
shown
in
Fig.
3,
insert
the removable
plug
in the
proper
tap
receptacle
and adjust
the
time-dial
to
the
proper
position.
The following
example
Il
lustrates
the procedure
in
making
a
relay
setting:
Assume
a
Type
[AC
relay
is used
in
a
circuit
where
the
circuit breaker
should
trip on
a
sustained
current
of
approximately
450 amperes;
also,
the
breaker
should
trip
in 1.0
second
on a
short-circuit
current
of
3750
amperes.
Assume
further
that
current
transformers
of 60/1
ratio
are
used.
The
current
tap
setting
is
found
by
dividing
the
minimum
primary
tripping
current
by
the current
transformer
ratio.
In this
case,
450
divided
by
60
equals
7.5
amperes.
Since there
is no 7.5
ampere
tap,
the
8-ampere
tap
is used.
To
find the
proper
time-dial
setting
to
give
1.0-second time
delay
at
3750
amperes,
divide
3750
by the
transformer
ratio.
This
gives
62.5
amperes
secondary
current
which
is 7.8
times
the
8-ampere
petting.
By
re
ferring
to
the time
current
curves
(Fig.
3),
it
will
be
seen that
7.8 times
the minimum
operating
current
gives
1.0-second
time
delay
when
the relay
is
set
on
the No.
6
time-dial
setting.
The
above
results
should
be checked
by means
of an
accurate
timing
device.
Slight
readjustment
of
the
dial
can
be made
until
the
desired
time
is
obtained.
13

GEH-1788
Type
IAC
Time
Overcurrent
Relay
Aid
in
making
the
proper
selection
of
relay
settings
may
be obtained
on
application
to
the
near
est Sales
Office
of
the
General
Electric
Company.
INSTANTANEOUS
UNIT
Select
the
current
above
which
is
desired
to
have
the
instantaneous
unit
operate
and
set
the
adjustable
pole
piece
so
that
the top
of
its
hexagon
head
is
even
with
the
desired
calibration
on
the
scale.
To
raise
or lower
the
pole
piece,
loosen
the
locknut
and
turn
it
up
or down
and
then
tighten
in
position.
The
contacts
should
be
adjusted
to
make
at
about
the
same
time
and
to
have
approximately
1/8
inch
wipe.
This
adjustment
can
be
made
by
loosening
the
screws
holding
the
stationary
contacts
and
moving
the contacts
up or
down
as
required.
A-C
TRIPPING
UNIT
The
a-c
tripping
unit
should
not
require
any
attention
other
than
occasional
cleaning
of
the con
tacts.
However,
if
the
adjustment
should
be
lost,
it
may
be
restored
as
follows:
CONTACT
ADJUSTMENT
With
the
unit
de-energized,
the
movable
contact
should
lie against
the
stationary
contact
with enough
tension
to
always
insure
a
good
closed
circuit.
The
movable
contact
brush
should
be
free
of
any
kinks.
Also this
contact
brush
should
not
touch
the
com
pound
bushing
supported from
the top
of
the
arma
ture.
The
brass
backing
strip
should
be
adjusted
to
allow a
1/16-inch
contact
gap
with
the
contacts
open.
The
compound
bushing
support
should
be
adjusted
to
allow
the
back
of the
movable
contact
to just
touch
the
brass
backing
strip
when
the
armature
operates
to
open
the
contacts.
The
outer
edge
of
the compound
bushing
should
be
approximate
ly 1/32 inch
from
the
inner
edge
of
the
stationary-
contact
supporting
post.
ARMATURE ADJUSTMENT
Loosen
the
two
screws
which
hold
the
armature-
assembly
bracket
to
the
bottom
of
the
frame.
Slide
the
bracket
in
or
out,
whichever
is
necessary,
until
the
armature
just
touches
the
pole
face
of
the
upper
core.
In
this position,
the
armature
should
be
about
1/32
inch
from
the
pole
face
of
the lower
core.
Next,
slide
the
bracket
in
until
the
armature
leaf
spring
assumes
a
vertical
position
and
is
FigJ9
Test
Connections
for Testing
Pickup &
Time
Curve
of
JAC
Relays
spaced
clear
of
both
armature
and the
vertical
tip
of
the
bracket.
With
this
setting,
the
armature
should
be
flush
against
the
pole
face
of
both
cores,
and
should
put
enough
pressure
on
the
armature
to
always
return
it
flush
against
the pole
face
of
the
lower
core
after
each
operation
of
the
unit.
This
alignment
is
important as
a
slight
gap
between
armature
and
pole
face
of
the
lower
core
after
the
unit
operates
may
cause contacts
to
open
momen
tarily,
dropping
the
relay
target
when the
circuit
breaker
is
reclosed.
Under
these
conditions,
the
momentary
opening
of
the
contacts
is
due
to
the
shock
of
the
armature
being
pulled
in
against
the
pole
face
when
the
lower
coil
is
energized.
Ex
cessive
pressure
on
the
armature,
caused
by
the
bracket
being
pushed
in too
far,
will
result
in
too
high
a
pickup
or
chattering
of
the
movable
contact
during
operation
of
the
unit.
Tighten
the
bracket
screws
securely
after
the
proper
adjustment
has
been
obtained.
OPERATION
The
pick-up
current
should
be
checked
on
one
Before
the
relay
is
put
into
service
it
should
be
or more
of
the taps
and
the
time
should
be
checked
given
a
check
to
determine
that
factory
adjust-
for
one
or
more
dial
settings.
ments
have
not
been
disturbed.
The
time
dial
will
be
set
at
zero
before
the
relay
leaves
the
Recommended
test
connections
for
the
above’
factory.
It
is
necessary
to
change
this
setting
in
test
are
shown
in
Fig.
19.
order
to
open
the
relay
contacts.
)
NUICAI
IN’
1_IGIlT
-
-
wtN
iTCNG
Pri’up
ç
VAN
51
IIA:3
TE1T FLI.G
10 INDICATING
LIGHT
N
CHECKING
PICKUP
o;
SlANT
ANELIL5 UN
IT
‘0
TO ACCURATELY
R{PROWCE
RELAY
CHARACTERISTICS
ALL
T[STS
SHOULD
BE
MADE
WITH RELAY
IN
CASE.
10
TM[P
“START”
I
L’IN.
RFCWU[NDED VOLTS,
120
A!
RATED
FR[UENCY
14

Type
IAC
Time
Overcurrent
Relay
GEH-1788
MAiNTENANCE
DISK
AND
BEARINGS
The
lower jewel
may
be tested
for
cracks
by
exploring
its
surface
with
the
point
of
a
fine
needle.
The
jewel
should
be
turned
up until
the
disk
is
centered
in
the
air
gaps,
after
which
it
should
be
locked
in
this
position
by the
set
screw
provided
for
this
purpose.
CONTACT
CLEANING
For
cleaning
fine
silver
contacts,
a
flexible
burnishing
tool should
be used.
This
consists
of
a
flexible
strip
of
metal
with
an
etched roughened
surface,
resembling
in
effect
a
superfine file.
The
polishing action
is
so
delicate
that
no
scratches
are
left, yet
corroded
material
will
be
removed
rapidly
and
thoroughly.
The
flexibility
of
the
tool
insures
the cleaning
of
the
actual
points
of contact.
Fine
silver
contacts
should not
be
cleaned
with
knives,
files,
or
abrasive
paper or
cloth.
Knives
or
files
may
leave
scratches
which
increase
arcing
and
deterioration
of
the
contacts. Abrasive paper
or
cloth
may
leave minute
particles
of
insulating
abrasive
material
in
the
contacts
and
thus
prevent
closing.
The
burnishing
tool
described
is
included
in
the
standard
relay
tool
kit
obtainable
from
the factory.
PERIODIC
TESTING
It
is
recommended
that
pickup
of
au units
be
checked
at
least
once
every
six
months.
ACCEPTANCE
TESTS
A.
MAIN
UNIT
Pickup
ELECTRICAL
Set
the
relay
at
the
0.5
time
dial
position
and
minimum
tap,
Using
the
test
connections
of Figure
19
the
main
unit
should
close
its
contacts
within
±5%
of
tap
value
current.
Time
Test
Set
the relay
at
the
5.0 time
dial
position
and
minimum
tap.
Using
the
test
connections
of
Figure
19,
and applying
5
times
pickup
current,
the
relay
should
operate
at
1.31
seconds
±7%.
With
2
times
pickup
current
applied
the operating
time
should
be
7.21
seconds
±7%.
With
10
times
pickup
current
applied
the
operating
time
should
be 0.72
seconds
±
7%.
B.
INSTANTANEOUS UNIT
Pickup
With
gradually
applied
current
the
unit
should
pickup
at
±10%
of the
minimum
calibration.
There
should
be
no
more
than
±5%
variation
on
repeated
pickup
checks.
Be
sure
the
target
has
been
reset
after
each
test.
C.
TARGET
SEAL
IN UNIT
Pickup
The
unit
should pickup
between
75
and
100%
of
tap value
with
the main
unit
contacts
closed.
Dropout
Open
the
main
unit
contacts,
the
seal
in
unit
should
remain
picked
up.
Reduce the
current
to 25%
of
tap value;
the
unit
should
drop
out.
RENEWAL
PARTS
It
is
recommended
that
sufficient quantities
of
renewal
parts
be
carried
in
stock
to
enable
the
prompt
replacement
of
any
that
are
worn,
broken,
or
damaged.
When
ordering
renewal
parts,
address
the
nearest
Sales
Office
of the
General
Electric
Com
pany,
specify
the
quantity
required
and
describing
the
parts
by
catalogue
numbers
as
shown
in
Renewal
Parts
Bulletin
No.
GEF-3883.
15

GEH-l7B
Type
IAC
Time
Overcurrent
Relay
1,125
29MM
PANEL
DRILLING
FUR
SEMI-FLUSH
MOUNTING
FRONT
VIEW
CASE
4)
10-32
X
3/9
MTG.
SCREWS
PANEL
DRILLANG
FUR
SURFACE
MOUNTING
FRONT
VIEW
Fig.
20
(K-6209271
181)
Outline
and
Panel
Drilling
Dimensions
for
Relay
Types
IAC
Relays
(11/91)
(200)
PANEL
LOCATION
SEMI-FLUSH
SURFACE
MTG. MTG.
—
(2)
5/16—18
STUDS
FUR
SURFACE
MTG.
75
MM
:1/4
DRILL
4
HOLES
1
0—32
STUDS
-
STUD
NUMBER
I
NG
97531
00000
00000
10
8 6
‘
2
6.187
157MM
BACK
VIEW
5/8
DRILL
2
HOLES
l5Mi
4
406
12MM
I—
--;---
CUTLUT
CUTOUT
MAY
REPLACE
DRILLED
HOLES
8.812
223MM
1.
156
29MM
218.
5MM
____
843
•i
72MM 1
5,
687
14
4MM
5
25
133MM
.500
12MM
(TYPICAL)
3/4
DRILL
10
HOLES
19MM
TYPiCAL
DIM.
INCHES
MM
5/16-18
STUD
___
3.0
76MM
VIEW SHOWING
ASSEMBLY
OF
HARDWARE
FUR
SURFACE
MTG.
ON
STEEL PANELS
GENERAL ELECTRIC
CO., POWER
SYSTEMS MANAGEMENT BUSINESS
DEPT..
MALVERN,
PA. 19355