GE IAC55A User manual
INSTRUCTIONS
GEI
-
31010
E
INSERT
BOOKLET
GEH
-
1753
SUPERSEDES
GEI
-
31010
D
SHORT
-
TIME
OVERCURRENT
RELAYS
IAC
55
A
IAC
55
B
IAC
55
F
These
instructions
do
not
purport
to
cover
ell
details
or
variations
in
equipment
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
sufficientJy
for
the
purchaser
'
s
purposes
,
the
matter
should
be
referred
to
the
General
Electric
Company
.
Should
To
the
extent
required
the
products
described
herein
meet
applicable
ANSI
,
IEEE
and
NEMA
standards
;
hut
no
such
assurance
is
given
with
respect
to
local
codes
and
ordinances
because
they
vary
greatly
.
GENERAL
ELECTRIC
Courtesy of NationalSwitchgear.com
GEI
-
31010
SHORT
TIME
OVERCURRENT
RELAYS
TYPES
IAC
55
AND
56
INTRODUCTION
Types
IAC
55
A
and
55
B
are
of
the
same
general
construction
as
Types
IAC
51
A
and
51
B
respectively
as
been
altered
,
how
-
described
in
the
included
instructions
GEH
-
1753
.
Some
of
the
parts
to
these
relays
ha
ever
to
give
short
operating
times
.
The
most
obvious
of
the
changes
are
that
the
U
-
magnet
is
mounted
on
the
opposite
side
and
the
spiral
cut
-
out
of
the
disk
has
been
omitted
.
The
former
is
of
little
importance
but
the
latter
means
that
there
is
no
compensation
for
the
windup
of
the
control
spring
.
This
means
that
more
current
is
required
,
in
the
operating
coil
,
to
close
the
contacts
than
to
start
the
disk
turning
from
the
No
.
10
timing
position
.
This
ratio
is
approximately
1.4
to
1
and
will
not
be
of
much
importance
on
the
applications
to
which
this
relay
is
usually
applied
.
Since
these
relays
operate
at
a
very
high
torque
level
,
they
are
supplied
with
a
"
locked
"
time
dial
,
to
prevent
any
possible
change
in
setting
due
to
this
high
torque
.
To
change
a
time
dial
setting
,
loosen
the
two
screws
in
the
dial
hub
,
turn
the
time
dial
to
the
described
setting
and
retighten
the
screws
.
Typical
time
-
current
curves
for
these
relays
are
shown
in
Fig
.
1
of
this
instruction
book
.
Outline
and
panel
drilling
as
well
as
internal
connections
for
these
relays
are
found
in
the
included
instructions
,
GEH
-
1753
,
and
Table
I
,
as
follows
:
TABLE
I
OUTLINE
AND
PANEL
DRILLING
INTERNAL
CONNECTION
TYPES
IAC
55
A
(
-
)
A
IAC
55
B
(
-
)
A
IAC
55
F
(
-
)
A
Fig
.
11
Fig
.
12
Fig
.
2
(
This
Supplement
)
Fig
.
18
Fig
.
18
Fig
.
18
BURDENS
Burdens
for
the
time
overcurrent
unit
are
given
in
Table
II
.
TABLE
II
RANGE
HZ
MIN
.
BURDENS
AT
MIN
.
PICKUP
MIN
.
TAP
BURDENS
IN
OHMS
(
Z
)
V
.
A
.
AT
5
AMPS
CALCULATED
FROM
IMPEDANCE
AT
MIN
PICKUP
TAP
3
10
20.0
R
JX
z
TIMES
PICKUP
TIMES
PICKUP
TIMES
PICKUP
0.5
-
2
13.4
60
0.5
51.6
49.8
21.6
46.6
13.5
1290
1.5
-
6
60
1.5
1.5
5.55
5.75
2.4
1.5
144
5.2
16
4
60
4
0.23
0.78
0.81
0.73
0.34
0.21
20
NOTE
:
The
impedance
values
given
are
those
for
minimum
tap
of
each
relay
,
the
impedance
for
other
taps
at
pick
up
current
(
tap
rating
)
varies
inversely
,
(
approximately
)
as
the
square
of
the
tap
rating
.
For
example
,
a
relay
with
0.5
-
2
amp
range
,
the
impedance
of
0.5
amp
tap
is
given
as
51.6
ohms
.
The
impedance
of
the
2.0
amp
tap
at
2.0
amperes
is
(
.
5
/
2
)
2
x
51.6
=
3.2
ohms
.
With
the
above
exceptions
,
the
included
instructions
,
GEH
-
1753
,
apply
to
these
types
in
every
respect
.
3
^
Inch
-
rates
Revision
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
TOP
PIVOT
TAP
BLOCK
TAP
PLUG
SEAL
-
IN
UNIT
HOLDING
COIL
TIME
DIAL
SEAL
-
IN
TARGET
DISK
SHAFT
SEAL
-
IN
UNIT
STATIONARY
CONTACT
,
LEFT
MAIN
MOVING
SHAFT
SEAL
-
IN
UNIT
STATIONARY
CONTACT
,
RIGHT
-
MAIN
STATIONARY
BRUSH
AND
CONTACT
ASSEMBLY
SEAL
-
IN
MOVING
CONTACT
ASSEMBLY
—
-
ktNERAL
(
M
S
^
UlMjj
II
MO
DISK
"
'
•
'
MB
•
*
>
"
N
(
!
UNIT
DRAG
MAGNET
(
8006996
)
Front
View
CRADLE
DISK
AND
SHAFT
COIL
,
MAGNET
,
AND
TAP
SLOCK
.
ASSEMBLY
LOWER
JEWEL
SCREW
B
-
(
8006997
)
Rear
View
The
Induction
Unit
for
Type
IAC
Re
lays
„
Figure
1
.
2
Courtesy of NationalSwitchgear.com
TIME
-
OVERCURRENT
RELAYS
TYPE
IAC
INTRODUCTION
Outline
&
Panel
Drilling
Contact
Circuits
AC
Trip
Induction
Unit
Instantaneous
Unit
Internal
Connection
Type
Unit
One
One
One
Two
Two
Fig
.
11
Fig
.
12
Fig
.
13
Fig
.
14
Fig
.
15
One
One
One
One
One
Fig
.
18
Fig
.
18
Fig
.
18
Fig
.
18
Fig
.
18
IAC
51
A
(
-
)
A
IAC
51
B
(
-
)
A
IAC
51
R
(
-
)
A
LAC
52
A
(
-
)
A
IAC
52
B
(
-
)
A
No
No
Yes
Yes
No
Yes
No
No
Yes
No
The
Type
IAC
relays
comprise
a
group
of
relays
that
are
employed
to
protect
against
overcurrent
on
single
-
phase
and
polyphase
circuits
.
The
various
relays
in
this
IAC
group
are
identified
by
model
numbers
,
and
the
relays
differ
in
the
number
of
circuits
they
close
,
the
length
of
time
delay
and
features
that
are
determined
by
the
characteristics
of
the
protected
circuit
.
These
relays
consist
of
an
induction
unit
or
an
induction
unit
with
an
instantaneous
unit
which
permits
instantaneous
tripping
for
extremely
high
currents
,
or
an
induction
unit
with
an
a
-
c
tripping
unit
for
use
where
d
-
c
power
is
unavailable
or
a
-
c
tripping
is
preferred
.
Since
practically
all
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
con
-
venience
,
described
separately
in
the
following
text
.
The
above
table
indicates
the
units
comprising
each
type
and
also
lists
the
internal
connections
and
out
-
line
and
panel
drilling
diagrams
.
INDUCTION
UNIT
APPLICATION
INTRODUCTION
The
induction
unit
is
the
main
unit
in
all
IAC
relays
,
supplying
the
inverse
time
delay
character
-
istics
of
the
relay
and
sounding
an
alarm
or
tripping
the
breakers
for
overload
currents
which
cause
it
to
close
its
contacts
.
The
induction
unit
is
the
basic
unit
in
all
IAC
relays
.
Fig
.
1
shows
the
induction
unit
mounted
in
the
cradle
.
These
units
are
of
the
induction
-
disk
construction
type
.
The
disk
is
actuated
by
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
.
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
-
current
characteristics
are
shown
in
Fig
.
2
.
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
.
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
.
RATINGS
The
induction
element
is
designed
to
use
any
one
of
three
operating
coils
,
each
having
a
different
combination
of
taps
as
follows
:
4
,
5
,
6
,
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
am
-
peres
.
When
the
These
instructions
do
not
purport
to
cover
all
details
or
variations
in
equipment
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
,
IEEE
and
NEMA
standards
;
but
no
such
assurance
is
given
with
respect
to
local
codes
and
ordinances
because
they
vary
greatly
.
Should
3
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
20
10
«
EL
Yv
X
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7
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v
\
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X
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>
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tn
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a
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a
>
E
i
H
JJI
.
08
.
07
.
08
.
05
.
04
.
03
.
02
.
01
.
9
.
8
.
7
.
8
.
A
1
3
4
51789
1 0
20
30
40
50
60
70
80
80
g
MULTIPLES
OF
RELAY
TAP
SETTING
(
0888
B
0269
[
3
]
)
Time
-
current
Curves
of
Type
IAC
Relays
with
Inverse
-
time
Characteristics
Fig
.
2
.
4
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
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
:
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
.
3
.
DUAL
RATED
0.6
/
2.0
0.2
/
2.0
2.0
0.6
2.0
0.2
3.5
Carry
30
amps
for
(
sec
)
Carry
10
amps
for
(
sec
)
Carry
continuously
(
amp
)
Minimum
operating
(
amp
)
Minimum
dropout
DC
resistance
60
hertz
impedance
50
hertz
impedance
0.05
2.2
0.5
Coil
Amperes
Volt
-
Amps
Imp
.
Ohms
30
20
5.0
Freq
.
0.45
Tap
PF
1.2
0.37
2.3
2.6
0.2
2.0
0.6
2.0
4
-
16
60
4.0
8.8
0.35
0.29
0.15
0.05
0.5 0.5
(
amp
)
(
ohms
)
(
ohms
)
(
ohms
)
0.78
8.3
0.24
0.18
50
0.32
4.0
8.0
0.31
6.2
0.65
0.65
50
25
0.36
4.0
7.5
0.30
0.54
42
0.54
5.1
1.5
-
6.0
60
1.5
59.0
2.36
0.26
50
1.5
52.0
2.08
0.28
If
the
tripping
current
exceeds
30
amperes
,
an
auxiliary
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
.
25
1.5
48.0
1.92
0.34
0.5
-
2.0
60
21.2
0.5
530.0
470.0
430.0
0.26
50
0.5
18.8
0.28
25
0.5
17.2
0.34
TAP
RANGE
.
5
-
2.0
TAP
RANGE
i
.
5
-
6.0
AMPS
.
TAP
RANGE
'
4
-
16
AMPS
.
MULTIPLES
OF
MINIMUM
TAP
SETTING
SATURATION
CURVES
AT
VARIOUS
FREQUENCIES
FOR
3
TAP
RANGES
OF
THE
TYPE
IAC
51
A
RELAY
LOWEST
TAP
USED
IN
ALL
CASES
Fig
.
3
.
(
K
-
6306891
-
1
)
Saturation
Curves
for
Lowest
Taps
of
the
Induction
Unit
of
Type
IAC
Relays
with
Inverse
-
time
Characteristics
.
5
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
A
-
*
C
eus
TRIP
BUS
1
2
n
3
51
=
1
T
LJ
DEVICE
FUNCTION
NUMBERS
FOR
USE
WITH
ALL
EXTERNAL
DIAGRAMS
2
=
Z
52
'
i
5
it
51
=
2
21
=
1
H
1
X
1
50
Instantaneous
Unit
%
Hi
w
-
6
51
Overcurrent
,
Relay
,
Type
IAC
Ground
Overcurrent
Relay
,
Type
IAC
Power
Circuit
Breaker
51
N
52
SI
Seal
-
in
Unit
,
with
Target
Fig
.
4
(
K
-
6375667
-
2
)
External
Connections
of
Three
Type
IAC
51
A
Relays
used
for
Phase
-
to
-
Phase
and
Ground
Overcurrent
Portection
of
a
3
-
Phase
Circuit
.
TC
Trip
Coil
Auxiliary
contact
,
closed
when
breaker
closes
.
A
A
-
C
BUS
1
2
3
A
-
C
BUS
1
JLL
2
3
12
*
n
A
-
C
TRIPPING
-
.
.
1
X
1
‘
UNIT
51
~
lj
llrl
%
51
=
1
H
'
*
"
II
4
»
X
If
n
J
5
$
i
3
14
51
=
1
51
=
1
TR
|
PP
|
NG
Re
ACTOR
4
-
*
1
I
Fig
.
6
(
K
-
6375669
-
6
)
External
Connections
of
Three
Type
IAC
51
R
Relays
used
for
3
-
Phase
Circuit
Protection
.
Fig
.
5
(
K
6375668
-
1
)
External
Connections
of
Three
Type
IAC
51
A
Relays
used
in
Conjunction
with
Tripping
Reactors
for
Protection
of
aTThree
-
Phase
Circuit
.
6
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
INSTANTANEOUS
UNIT
INTRODUCTION
mounted
beside
the
adjustable
pole
piece
,
current
characteristics
are
shown
in
Time
-
Fig
.
10
.
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
.
7
)
.
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
apredetermined
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
.
RATINGS
The
instantaneous
unit
is
designed
to
use
either
of
two
coils
having
pickup
ranges
of
10
to
40
,
and
20
to
80
amperes
respectively
.
The
current
-
closing
rating
of
the
contacts
is
30
amperes
for
voltages
not
exceeding
250
volts
.
BURDENS
Burden
data
on
the
instantaneous
unit
coils
are
given
in
the
following
table
:
APPLICATION
Imp
.
Ohms
Volt
PF
Coil
Freq
.
Amp
.
Amp
The
instantaneous
unit
is
used
on
certain
IAC
relay
models
to
provide
instantaneous
tripping
for
current
exceeding
a
predetermined
value
.
10
-
40
60
0.83
0.95
5
0.033
0.032
0.027
0.008
0.008
0.007
50
0.80
0.95
5
25
0.65
0.98
5
OPERATING
CHARACTERISTICS
60
0.21
0.95
20
-
80
5
The
instantaneous
element
operates
over
a
4
to
1
range
and
has
its
calibration
stamped
on
a
scale
50
0.20
0.95
5
0.15
0.98
25
5
-
CALIBRATION
!
PLATE
'
ADJUSTABLE
POLE
PIECE
ifggjl
INSTANTANEOUS
UNIT
VfiSii
,
m
OPERATING
Bit
]
_
m
COIL
m
:
m
SHORTING
CONTACTS
.
.
.
TARGET
STATIONARY
CONTACTS
COIL
so
MAIN
COIL
ft
•
s
;
1
iSiiili
MOVING
CONTACT
ASSEMBLY
A
-
C
TRIPPING
MSI
*
1
*
M
UNIT
•
>
HMC
TIME
A
/
A
«
UNIT
IS
-
.
#
li
^
r
i
I
U
fS
r
Fig
.
8
,
(
8007060
)
Type
IAC
Relay
with
A
-
C
Tripping
Unit
.
Fig
.
7
.
(
8006998
)
Type
IAC
Relay
with
an
Instantaneous
Unit
.
an
7
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
A
-
C
TRIPPING
UNIT
INTRODUCTION
The
a
-
c
tripping
unit
is
a
Type
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
IAC
relay
.
It
transfers
the
current
from
the
secondary
of
the
current
trans
-
former
into
the
trip
coil
and
removes
the
current
from
the
trip
coil
when
the
breaker
trips
.
The
tripping
unit
is
mounted
on
the
rear
of
the
frame
opposite
the
tapped
operating
coil
of
the
induction
unit
(
see
Fig
.
8
)
.
The
operation
of
this
unit
is
illustrated
in
Fig
.
9
.
The
secondary
current
circulates
through
the
induction
unit
current
coil
and
the
main
coil
of
the
REA
auxiliary
tripping
unit
,
returning
through
the
REA
contacts
to
the
current
transformer
.
Normally
,
most
of
the
flux
generated
by
the
main
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
REA
is
short
-
circuited
and
current
flows
in
this
coil
by
transformer
action
,
causing
a
redistribution
of
flux
which
actuates
the
armature
and
the
REA
contacts
.
The
opening
of
the
REA
contacts
causes
the
secondary
current
to
flow
through
the
trip
coil
which
trips
the
breaker
.
TdSI
BREAKER
TRIP
COIL
CURRENT
TRANS
AC
TRIP
UNIT
NORMALLY
CLOSED
CONTACTS
IOC
j
:
:
icc
f
LQC
AC
TRIP
UNIT
SHORTING
J
con
o
v
AC
TRIP
UNIT
MAIN
COIL
TOC
Fig
.
9
(
K
-
6154766
-
2
)
Diagram
Illustrating
Operation
of
Type
IAC
Relays
having
an
A
-
C
Tripping
Unit
.
0.030
K
T
T
OPERATING
TIME
RANGE
FOR
ANY
PICKUP
SETTING
0.025
<
J
>
Ul
<
/
>
0.020
i
UJ
*
-
0.015
a
.
Jc
<
-
>
0.010
Q
-
0.005
0
2
0
3
10
5
6
7
b
4
y
MULTIPLES
OF
PICK
-
UP
(
6306872
[
5
]
)
Time
-
current
Characteristics
of
Original
Instantaneous
Unit
Fig
.
10
8
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
APPLICATION
which
has
contacts
rated
200
amperes
,
can
be
used
in
conjunction
with
IAC
overcurrent
relays
.
The
REA
11
B
is
not
mounted
inside
the
IAC
case
.
The
a
-
c
tripping
unit
is
used
in
Type
IAC
relays
where
a
reliable
direct
-
current
tripping
source
is
not
available
and
it
is
necessary
to
trip
the
breaker
from
the
current
-
transformer
secondary
.
BURDENS
Burdens
of
the
REA
unit
are
given
in
the
following
table
:
RATINGS
The
a
-
c
tripping
unit
has
a
continuous
rating
of
five
amperes
but
will
operate
on
a
minimum
current
of
3.5
amperes
.
They
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
second
-
ary
current
exceeds
100
amperes
,
the
REA
1
IB
relay
,
Impedance
in
Ohms
Volt
-
Amperes
Amp
Frequency
PF
5
60
0.49
0.80
12.2
0.33
0.85
50
5
8.4
5
0.62
0.23
5.8
25
RECEIVING
,
HANDLING
AND
STORAGE
packing
the
relay
in
order
that
none
of
the
parts
are
injured
or
the
adjustments
disturbed
.
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
the
relay
,
an
examination
should
be
made
for
any
damage
sustained
during
shipment
,
injury
or
damage
resulting
from
rough
handling
is
evident
,
a
claim
should
be
filed
at
once
with
the
transportation
company
and
the
nearest
Sales
Office
of
the
General
Electric
Company
notified
promptly
.
Reasonable
care
should
be
exercised
in
un
-
If
the
relays
are
not
to
be
installed
immediately
,
they
should
be
stored
in
their
original
cartons
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
.
If
INDUCTION
UNIT
-
T
1
INDUCTION
±
UNIT
\
INSTANT
SEAL
-
IN
UNIT
,
UNIT
SEAL
-
I N
UNIT
7
T T
V
v
v
*
V
NJ
/
v
^
•
y
*
v
‘
"
V
i
v
6
3
5
1
1
5
6
o
2
2
6
6
INTERNAL
CONNECTIONS
(
FRONT
VIEW
)
*
-
S H
0
R T
FINGER
SHORT
FINGER
Fig
.
12
.
(
K
-
6209661
[
11
)
Internal
Connections
for
the
Type
IAC
51
B
Relay
(
Front
View
)
11
,
(
K
-
6209658
-
10
)
Internal
Connections
for
Fig
.
the
Type
IAC
5
LA
Relay
(
Front
View
)
.
9
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
£
A
-
C
TRIP
UNIT
INDUCTION
UN
;
7
SEAL
-
IN
•
UK
I
T
1
/
*
i
k
SEAL
-
IN
UN
:
:
zz
A
-
C
TRIP
/
'
UNIT
N
U
“
i
s
S
N
INSTANT
.
T
U
LI
T
A
T
N
T
V
Vr
—
V
V
V
v
N
/
~
V
V
V
V
V
I
9
1
5
7
3
O
O
o
6
2
4
8
10
Fig
.
13
(
K
-
6209294
-
3
)
Internal
Connections
for
the
Type
IAC
51
R
Relay
(
Front
View
)
INDUCTION
INDUCTION
/
A
UNIT
SI
T
T
SI
T
SEAL
-
IN
UNIT
W
’
4
0
4
3
1
5
4
6
2
6
SHORT
FINGER
Fig
.
14
(
K
-
6209662
[
5
]
)
Internal
Connections
for
the
Type
IAC
52
A
Relay
(
Front
View
)
10
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
I
NDUCTION
\
UNIT
x
-
!
>
!
fvL
TO
TIMER
"
STOP
"
TC
INDICATING
LIGHT
WHEN
CHECKING
PICKUP
OF
MAIN
UNIT
.
k
9
—
>
TO
INDICATING
LIGHT
WHEI
CHECKING
PICKUP
0
^
INSTANTANEOUS
UNIT
SEAL
-
IN
UNIT
INSTANT
.
UNIT
n
.
66606
1
2
3
4
5
INDUCTION
UN
|
T
OOOO
7
8
9
10
6
XLA
13
TEST
PLUG
A
J
INSTANT
.
UNIT
VARIABLE
RESISTOR
TO
TIMER
"
START
”
w
•
V
*
V
135
9
-
*
TO
ACCURATELY
REPRODUCE
RELAY
CHARACTERISTICS
ALL
TESTS
SHOULD
BE
MADE
WITH
RELAY
IN
CASE
.
/
/
I
1
o
2
6
10
MIN
.
RECOMMENDED
VOLTS
,
120
AT
RATED
FREQUENCY
•
*
SHORT
FINGER
^
8
*
15
(
K
-
6209663
[
8
]
)
Internal
Connections
for
the
Type
IAC
52
B
Relay
(
Front
View
)
Fig
.
16
(
K
-
6154399
-
7
)
Testing
Connections
for
Type
IAC
Relays
such
as
Type
IAC
51
A
INSTALLATION
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
secondary
cir
-
cuits
from
being
opened
.
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
diagrams
are
shown
in
Figs
.
20
and
21
.
CONNECTING
PLUG
MAIN
BRUSH
CONNECTING
BLOCK
CONNECTIONS
Internal
connection
diagrams
for
the
various
relay
types
are
shown
in
Fig
.
11
to
17
inclusive
.
Typical
wiring
diagrams
are
given
in
Fig
.
4
to
6
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
.
TERMINAL
BLOCK
AUXILIARY
BRUSH
INSPECTION
NOTE
:
AFTER
ENGAGING
AUXILIARY
BRUSH
,
CONNECTING
PLUG
TRAVELS
«
/
4
INCH
BEFORE
ENGAGING
THE
MAIN
BRUSH
ON
"
HE
TERMINAL
BLOCK
.
At
the
time
of
installation
,
the
relay
should
be
inspected
for
tarnished
contacts
,
loose
screws
,
or
other
imperfections
.
If
any
trouble
is
found
,
it
should
be
corrected
in
the
manner
described
under
MAINTENANCE
.
CAUTION
:
Fig
.
17
(
8025039
)
Cross
Section
of
Drawout
Case
Showing
Position
of
Auxiliary
Brush
.
Every
circuit
in
the
drawout
case
has
an
auxi
-
liary
brush
.
It
is
especially
important
on
current
11
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
ADJUSTMENTS
TARGET
AND
SEAL
-
IN
UNIT
The
primary
adjustment
for
the
time
of
opera
-
tion
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
disk
shaft
decreases
the
time
,
while
moving
it
away
increases
the
time
.
For
trip
coils
operating
on
currents
ranging
from
0.2
up
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
volt
-
age
,
place
the
tap
plug
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
station
-
ary
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
neces
-
sary
to
prevent
the
right
-
hand
stationary
contact
from
getting
out
of
adjustment
.
Screws
should
not
be
in
both
taps
at
the
same
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
in
-
sure
the
proper
sequence
in
the
operation
of
the
several
circuit
breakers
.
Allowance
must
fye
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
difference
of
about
0.5
second
(
at
the
maximum
current
)
between
relays
whose
opera
-
tion
is
to
be
selective
.
EXAMPLE
OF
SETTING
The
time
and
current
settings
of
the
overcurrent
unit
can
be
made
easily
and
quickly
.
Each
time
value
shown
in
Fig
.
2
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
.
2
,
insert
the
removable
plug
in
the
proper
tap
re
-
ceptacle
and
adjust
the
time
-
dial
to
the
proper
position
.
procedure
in
making
a
relay
setting
.
INDUCTION
UNIT
CURRENT
SETTING
The
tap
plug
must
not
be
removed
without
first
withdrawing
the
connecting
plug
.
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
cur
-
rent
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
screw
driver
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
between
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
mini
-
mum
current
within
five
percent
of
the
tap
-
plug
setting
.
The
unit
resets
at
90
per
cent
of
the
mini
-
mum
closing
value
.
TIME
SETTING
The
setting
of
the
time
dial
determines
the
length
of
time
the
unit
requires
to
close
its
contacts
when
the
current
reaches
a
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
there
-
fore
this
setting
gives
the
maximum
time
setting
.
The
following
example
illustrates
the
Assume
a
Type
IAC
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
1.9
seconds
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
amps
.
Since
there
is
no
7.5
-
amp
tap
,
the
8
-
amp
.
tap
is
used
.
To
find
the
proper
time
-
dial
setting
to
give
1.9
seconds
time
delay
at
3750
am
-
peres
,
divide
3750
by
the
transformer
ratio
.
This
gives
62.5
amperes
secondary
current
which
is
7.8
times
the
8
-
ampere
setting
.
By
referring
to
the
time
current
curves
(
Fig
.
2
)
,
it
will
be
seen
that
7.8
times
the
minimum
operating
current
gives
1.9
seconds
time
delay
when
the
relay
is
set
slightly
above
the
No
.
6
time
-
dial
setting
.
The
above
results
should
be
checked
by
{
neans
of
an
accurate
timing
device
.
Slight
readjustment
of
the
dial
can
be
made
until
the
desired
time
is
obtained
.
Aid
in
making
the
proper
selection
of
relay
settings
may
be
obtained
on
application
to
the
nearest
Sales
Office
of
the
General
Electric
Company
.
12
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
CONTACT
ADJUSTMENT
1
.
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
com
-
pound
bushing
should
be
approximately
1
/
32
-
inch
from
the
inner
edge
of
the
stationary
contact
sup
-
porting
post
.
2
.
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
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
re
-
turn
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
momentarily
,
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
.
Excessive
pressure
on
the
arma
-
ture
,
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
ad
-
justment
has
been
obtained
.
The
contacts
should
have
approximately
1
/
32
inch
wipe
.
That
is
,
the
stationary
contact
should
be
deflected
about
1
/
32
inch
when
the
disk
completes
its
travel
.
The
contact
wipe
is
adjusted
by
turning
the
screws
in
the
contact
brush
which
regulates
the
position
of
the
brush
,
in
relation
to
the
brush
stop
.
For
relays
with
two
circuit
-
closing
contacts
,
the
tips
should
be
in
the
same
vertical
plane
.
When
the
time
dial
is
moved
to
a
position
where
the
contacts
just
close
,
the
time
-
dial
scale
should
indicate
zero
.
If
this
is
found
incorrect
,
and
the
brushes
are
correctly
adjusted
,
regulate
the
dial
to
read
zero
.
This
is
done
by
changing
the
position
of
the
arm
attached
to
the
shaft
which
is
located
below
the
time
dial
.
Loosen
the
screw
which
clamps
the
arm
to
the
shaft
and
turn
the
arm
,
relative
to
the
shaft
,
until
the
contacts
just
make
at
the
zero
time
-
dial
setting
.
INSTANTANEOUS
UNIT
Select
the
current
above
which
is
desired
to
have
the
instantaneous
unit
operate
and
set
the
ad
-
justable
pole
piece
so
that
the
top
of
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
"
This
adjustment
can
be
made
by
loosening
wipe
.
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
:
OPERATION
The
pickup
current
should
be
checked
on
one
or
more
of
the
taps
and
the
time
should
be
checked
for
one
or
more
dial
settings
.
Recommended
test
connections
for
the
above
test
are
shown
in
Fig
.
18
.
Before
the
relay
is
put
into
service
it
should
be
given
a
check
to
determine
that
factory
adjustments
have
not
been
disturbed
.
The
time
-
dial
will
be
set
at
zero
before
the
relay
leaves
the
factory
.
It
is
necessary
to
change
this
setting
in
order
to
open
the
relay
contacts
.
MAINTENANCE
The
relays
are
adjusted
at
the
factory
and
it
is
advisable
not
to
disturb
the
adjustments
.
If
,
for
any
reason
,
they
have
been
disturbed
,
the
followingpoints
should
be
observed
in
restoring
them
:
exploring
its
surface
with
the
point
of
a
fine
needle
.
If
it
is
necessary
to
replace
the
jewel
a
new
pivot
should
be
screwed
into
the
bottom
of
the
shaft
at
the
shaft
at
the
same
time
.
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
.
DISK
AND
BEARINGS
The
lower
jewel
may
be
tested
for
cracks
by
13
Courtesy of NationalSwitchgear.com
GEH
-
1753
Time
Overcurrent
Relays
Type
IAC
CONTACT
CLEANING
and
deterioration
of
the
contacts
.
Abrasive
paper
or
cloth
may
leave
minute
particles
of
insulating
abrasive
material
in
the
contacts
and
thus
prevent
closing
.
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
The
burnishing
tool
described
above
can
be
obtained
from
the
factory
.
PERIODIC
TESTING
An
operation
test
and
inspection
of
the
relay
at
least
once
every
six
months
are
recommended
.
Test
connections
are
shown
in
Fig
.
18
.
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
.
pany
,
specify
quantity
required
,
name
of
part
wanted
,
and
give
complete
nameplate
data
.
If
possible
,
give
the
General
Electric
Company
requisition
number
on
which
the
relay
was
furnished
.
For
a
recommended
parts
list
refer
to
Parts
Bulletin
number
GEF
-
3883
.
When
ordering
renewal
parts
,
address
the
nearest
Sales
Office
of
the
General
Electric
Com
-
rtt
SEI
94
IC
RATED
IMSTMTMWS
WIT
OPERATING
TIME
,
02
b
.
osgy
.
<
*
6
-
2
.
010
Ou
.
005
10
9
8
7
6
5
4
3
1.5
2
MULTIPLES
OF
PICKUP
Fig
.
19
(
0208
A
8695
{
1
)
)
Time
-
Current
Characteristics
for
the
"
Hi
-
G
"
Unit
Since
the
last
edition
,
Figures
12
and
14
have
been
revised
.
14
Courtesy of NationalSwitchgear.com
Time
Overcurrent
Relays
Type
IAC
GEH
-
1753
SEMI
-
FLUSH
MTG
.
PANEL
LOCATION
SURFACE
MTG
.
el
3
wii
-
-
6
rs
-
t
5
8
C
£
-
18
STUDS
FOR
A
0
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SCREW
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IG
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-
A
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FIG
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-
B
CASE
r
*
\
PANEL
STUD
NUMBERING
RELAY
TYPE
UAC
51
A
IAC
51
B
5
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A
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A
AC
51
C
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51
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52
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VIEW
SHOWING
ASSEMBLY
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MTG
.
ON
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.
OUTLINE
-
5
“
16
?
7
-
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27
7
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2
25
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8
8
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—
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LL
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FIG
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-
4
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LUNG
FOR
FIG
.
8
SURFACE
MTQ
.
-
FRONT
V
I
FA
IAC
51
B
,
IAC
51
R
,
IAC
52
A
and
IAC
52
B
Relays
and
Panel
Drilling
for
the
Type
IAC
51
A
,
Pig
.
18
(
237
C
707
-
1
)
Outline
15
Courtesy of NationalSwitchgear.com
This manual suits for next models
2
Table of contents
Other GE Relay manuals
