GE IAC77A User manual
GEK
-
34055
TABLE
OF
CONTENTS
PAGE
DESCRIPTION
APPLICATION
CONSTRUCTION
RATINGS
3
4
4
5
TIME
-
OVERCURRENT
UNIT
.
INSTANTANEOUS
UNIT
. .
TARGET
AND
SEAL
-
IN
UNIT
CONTACTS
5
6
7
8
BURDENS
CHARACTERISTICS
RECEIVING
,
HANDLING
,
AND
STORAGE
..
.
.
ACCEPTANCE
TESTS
VISUAL
INSPECTION
MECHANICAL
INSPECTION
ELECTRICAL
TESTS
DRAWOUT
RELAYS
GENERAL
POWER
REQUIREMENTS
GENERAL
..
.
TIME
-
OVERCURRENT
UNIT
PICKUP
TEST
TIME
TEST
INSTANTANEOUS
UNIT
SETTING
THE
INSTANTANEOUS
UNIT
PICK
UP
TESTS
TARGET
AND
SEAL
-
IN
UNIT
.
.
.
.
PICK
-
UP
AND
DROPOUT
TEST
.
.
8
9
9
10
.
10
10
11
11
11
11
12
12
.
12
12
13
13
13
14
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
-
OVERCURRENT
UNIT
TIME
TESTS
INSTANTANEOUS
UNIT
TARGET
AND
SEAL
-
IN
UNIT
RENEWAL
PARTS
14
14
14
15
15
15
15
15
15
16
16
17
18
18
18
(
Cover
photo
8041299
)
2
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TIME
OVERCURRENT
RELAYS
TYPES
IAC
77
A
,
77
B
,
78
A
,
78
B
FORM
800
and
UP
DESCRIPTION
nype
IAC
77
and
IAC
78
relays
are
single
-
phase
,
current
-
operated
,
AC
de
ices
with
extremely
inverse
time
/
current
characteristics
.
They
can
be
utilized
to
protect
commercial
,
industrial
,
and
utility
power
distribution
systems
against
either
multi
-
phase
or
phase
-
to
-
ground
faults
.
Each
relay
consists
of
a
basic
induction
-
disk
time
-
overcurrent
unit
,
and
a
dual
-
rated
target
/
seal
-
in
unit
,
and
may
include
a
hinge
-
type
instantaneous
-
overcurrent
unit
.
Both
the
time
-
overcurrent
unit
and
the
instantaneous
unit
are
adjustable
over
a
range
of
about
8
to
The
available
ranges
in
amperes
of
both
units
,
as
well
as
information
on
their
continuous
rating
,
contact
rating
,
and
target
/
seal
-
in
unit
tap
ratings
are
given
in
the
section
on
RATINGS
.
1
.
A
standard
SI
case
is
used
to
mount
each
relay
,
mounting
dimensions
of
this
case
are
shown
in
Figures
11
and
12
.
The
outline
and
The
basic
differences
between
the
relays
covered
by
these
instructions
are
noted
in
the
following
Table
I
.
TABLE
I
INSTANTANEOUS
CONTACT
CIRCUITS
INTERNAL
CONNECTIONS
TYPE
UNIT
IAC
77
A
IAC
77
B
IAC
78
A
IAC
78
B
1
FIGURE
4
FIGURE
5
FIGURE
6
FIGURE
7
NO
1
YES
2
NO
YES
2
These
instructions
do
not
purport
to
cover
all
details
or
variations
in
equipment
nor
provide
for
every
possible
contingency
to
be
met
in
connection
with
installation
,
operation
or
maintenance
.
Should
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
.
3
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GEK
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APPLICATION
The
extremely
inverse
time
/
current
characteristics
make
the
IAC
77
IAC
78
relays
particularly
well
suited
for
the
protection
of
In
such
applications
,
because
the
power
fuses
possible
to
obtain
and
primary
distribution
circuits
.
relay
characteristics
closely
parallel
those
of
the
normally
employed
in
these
circuits
,
it
is
selective
fault
protection
with
a
minimum
time
delay
.
The
unique
time
-
current
characteristics
of
these
relays
also
make
them
well
suited
for
picking
up
cold
loads
.
For
any
given
cold
load
pick
up
capability
,
the
resulting
setting
will
provide
faster
protection
at
high
fault
currents
with
the
extremely
inverse
relay
than
with
less
inverse
devices
.
The
general
practice
is
to
use
a
set
of
three
relays
for
interphase
faults
.
A
separate
relay
,
residually
connected
,
can
be
utilized
for
single
-
phase
-
to
-
ground
faults
.
Use
of
a
separate
ground
relay
is
advantageous
because
it
can
be
adjusted
to
provide
more
sensitive
protection
on
ground
faults
.
Typical
connections
for
applying
these
relays
are
shown
in
Figures
14
and
15
.
In
the
application
of
IAC
77
and
IAC
78
relays
with
automatic
reclosing
devices
,
the
reset
time
should
be
considered
.
The
reset
time
of
all
relays
covered
by
these
instructions
is
approximately
60
seconds
from
the
fully
-
closed
to
the
fully
-
open
position
,
when
set
at
number
10
on
the
time
dial
.
When
setting
these
relays
to
coordinate
with
"
downstream
"
relays
,
a
coordination
time
of
from
0.25
to
.
40
second
is
generally
allowed
.
These
coordination
times
include
,
in
addition
to
breaker
-
clearing
time
,
0.10
second
for
relay
overtravel
and
0.17
second
for
safety
factor
.
For
example
,
if
the
breaker
-
clearing
time
is
0.13
second
(
8
cycles
)
the
coordination
time
would
be
0.40
second
.
If
the
relay
time
is
set
by
test
at
the
current
level
in
question
,
the
safety
factor
may
be
reduced
from
0.17
to
0.07
second
.
Then
with
relay
overtravel
of
.
10
second
,
if
the
"
downstream
"
breaker
time
is
5
cycles
(
0.08
second
)
,
a
minimum
of
0.25
second
could
be
allowed
for
coordination
.
If
the
downstream
devices
are
fuses
rather
than
circuit
breakers
,
then
the
maximum
clearing
time
of
the
fuse
should
be
used
and
the
time
allowed
for
breaker
-
clearing
time
should
be
omitted
.
CONSTRUCTION
The
induction
unit
is
the
basic
unit
in
all
Type
-
IAC
relays
.
Figures
2
and
3
show
the
induction
unit
mounted
in
the
cradle
.
These
units
are
of
the
induction
-
disk
construction
type
.
The
disk
is
actuated
by
a
wattmetric
-
type
current
-
operating
element
.
This
is
similar
to
the
standard
element
as
used
in
watthour
meters
,
except
the
actuating
coils
above
and
below
the
operating
disk
are
connected
in
series
.
A
capacitor
and
variable
resistor
connected
in
series
with
the
inner
coil
on
the
upper
laminated
structure
makes
up
the
phase
-
shifting
circuit
.
contact
,
which
completes
the
trip
or
alarm
circuit
,
is
restrained
by
a
spiral
spring
to
give
proper
contact
-
closing
The
disk
shaft
carries
the
moving
The
disk
shaft
4
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GEK
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and
its
motion
is
retarded
by
a
permanent
magnet
acting
on
current
,
the
disk
to
give
correct
time
delay
.
There
is
a
target
and
seal
-
in
unit
mounted
on
the
front
,
to
the
left
of
the
shaft
of
the
time
-
overcurrent
unit
.
The
seal
-
in
unit
has
its
coil
in
series
and
its
contacts
in
parallel
with
the
contacts
of
the
time
-
overcurrent
unit
,
such
that
when
the
induction
-
unit
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
.
The
instantaneous
unit
is
a
small
hinge
-
type
unit
,
which
is
mounted
on
the
front
of
the
B
models
to
the
right
of
the
shaft
of
the
time
-
overcurrent
unit
.
Its
contacts
are
normally
connected
in
parallel
with
the
contacts
of
the
time
-
overcurrent
unit
and
its
coil
is
connected
in
series
with
the
time
-
overcurrent
unit
,
instantaneous
unit
picks
up
it
raises
a
target
,
which
latches
up
and
remains
exposed
until
it
is
released
,
the
target
of
the
seal
-
in
unit
also
releases
the
target
of
the
instantaneous
unit
.
When
the
The
same
button
that
releases
RATINGS
TIME
-
OVERCURRENT
UNIT
Ratings
of
the
time
-
overcurrent
unit
are
given
in
Table
II
.
TABLE
II
PICK
UP
RANGE
.
AMPERES
MAIN
(
TIME
)
FREQUENCY
CYCLES
INSTANTANEOUS
RELAY
UNIT
UNIT
0.5
-
4.0
1.5
-
12.0
2.0
-
15.0
IAC
77
A
and
IAC
78
A
50
60
0.5
-
4.0
1.5
-
12.0
2.0
-
15.0
0.5
-
4.0
2.0
-
16.0
10.0
-
80.0
20.0
-
160.0
IAC
77
B
and
IAC
78
B
50
60
Available
taps
of
the
t
ime
-
overcur
rent
unit
are
shown
on
Table
III
.
TABLE
III
TAPS
AVAILABLE
(
AMPERES
)
RANGE
,
AMPERES
0.5
,
0.6
,
0.7
,
0.8
1.0
,
1.2
,
1.5
,
2.0
,
2.5
,
3.0
,
4.0
0.5
-
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
in
Table
IV
.
5
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GEK
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TABLE
IV
TIME
OVERCURRENT
UNIT
(
AMPS
)
ONE
SECOND
RATING
(
AMPS
)
K
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
of
less
than
one
second
,
the
rating
may
be
calculated
according
to
the
formula
/
=
where
T
is
the
time
,
in
seconds
,
that
the
current
flows
.
The
continuous
ratings
of
the
time
-
overcurrent
units
are
shown
in
Table
V
.
TABLE
V
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
RATING
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
AMPRANGE
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
-
15.0
AMPRANGE
TAP
2.0
2.5
3.0
4.0
5.0
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
20.0
20.0
INSTANTANEOUS
UNIT
The
instantaneous
unit
has
a
double
-
wound
coil
for
operation
on
Any
setting
obtained
in
the
lower
range
either
one
of
two
ranges
.
(
series
connected
)
is
doubled
,
within
±
3
%
,
when
the
unit
is
connected
for
high
-
range
operation
(
parallel
connected
)
.
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GEK
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The
instantaneous
unit
has
a
continuous
rating
of
minimum
setting
or
25
amperes
,
whichever
is
smaller
.
2.0
-
16.0
ampere
instantaneous
unit
,
8.0
amperes
)
has
a
continuous
rating
of
3.0
connected
for
high
-
range
operation
(
4.0
-
16.0
continuous
rating
of
6.0
amperes
.
ratings
for
the
instantaneous
unit
are
shown
in
Table
VI
.
times
The
1.5
Example
:
when
set
on
the
low
range
(
2.0
-
amperes
,
and
when
amperes
)
has
a
The
continuous
and
one
-
second
TABLE
VI
RANGE
CONNECT
-
CONTINUOUS
RATING
t
ONE
SECOND
K
IONS
tt
0.5
-
4.0
0.5
2.0
S
4.0
P
0.75
25.0
625
1.0
1.5
50.0
2
,
500
2.0
-
16.0
2.0
130.0
260.0
16
,
900
67
,
600
8.0
S
16.0
P
3.0
4.0
6.0
10.0
-
80.0
10.0
-
40.0
S
20.0
-
80.0
P
15.0
160
,
000
360
,
000
400.0
600.0
25.0
20.0
-
160.0
20.0
-
80.0
S
40.0
-
160.0
P
25.0
600.0
600.0
360
,
000
360
,
000
25.0
t
Higher
currents
may
be
applied
for
shorter
lengths
of
time
in
accordance
with
the
formula
K
/
=
V
-
7
where
T
is
the
time
,
in
seconds
,
that
the
current
flows
.
tt
S
Series
connected
,
P
-
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
7
MIN
.
Operating
(
amperes
)
+
0
-
25
%
2.0
0.2
Carry
Continuously
(
amperes
)
0.3
3.0
Carry
30
Amps
for
(
sec
.
)
0.03
4.0
Carry
10
Amps
for
(
sec
.
)
0.25
30.0
60
Hz
Impedance
(
ohms
)
52.0
0.53
7
Courtesy of NationalSwitchgear.com
GEK
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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
of
the
target
and
seal
-
in
coils
of
the
protective
relay
.
CONTACTS
The
current
-
closing
rating
of
the
contacts
is
30
amperes
for
voltages
not
exceeding
250
volts
.
The
current
-
carrying
rating
is
limited
by
the
ratings
of
the
seal
-
in
unit
.
BURDENS
Burdens
for
the
time
-
overcur
rent
unit
are
given
in
Table
VIII
.
TABLE
VIII
BURDENS
AT
MIN
.
PICKUP
MIN
.
TAP
BURDENS
IN
OHMS
(
Z
)
V
.
A
.
AT
5
AMPS
3
10
20.0
CALCULATED
FROM
IMPEDANCE
AT
MIN
.
PICKUP
(
l
2
z
)
RANGE
HZ
MIN
.
R
Jx
Z
TAP
TIMES
TIMES
TIMES
PICK
-
PICK
-
PICK
-
UP UP
UP
0.5
-
0.4
60
0.5
0.80
1.38
1.60 1.60
1.60 1.60
40
1.5
-
12.0
60
1.5
0.085
.
147
0.17
0.17 0.17 0.17
4.25
2.0
-
15.0
60
2.0
0.05
0.086
0.099
0.10 0.10 0.10
2.5
The
impedance
values
given
are
those
for
the
minimum
tap
of
each
relay
.
cur
rent
NOTE
:
The
impedance
for
other
taps
at
(
tap
rating
)
varies
inversely
For
4.0
amp
range
,
the
1.60
ohms
.
pick
-
up
(
approximately
)
as
the
square
of
the
tap
rating
,
example
,
for
a
relay
with
0.5
impedance
of
the
0.5
amp
tap
is
given
as
The
impedance
of
the
2.0
amp
tap
at
2.0
amperes
is
(
.
5
/
2
)
2
x
1.6
or
0.10
ohm
.
8
Courtesy of NationalSwitchgear.com
GEK
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The
instantaneous
unit
burdens
are
listed
in
Table
IX
.
TABLE
IX
BURDENS
AT
MIN
.
PICKUP
MIN
.
TAP
BURDENS
IN
OHMS
(
Z
)
RANGE
60
HZ
RELAYS
CON
-
MIN
.
NEC
-
TAP
TIONS
AMPS
R
Jx
Z
3
10
20.0
OHMS OHMS
OHMS
TIMES
TIMES
TIMES
PICK PICK
PICK
V
.
A
.
AT
5
AMPS
CALCULATED
FROM
IMPEDANCE
AT
MIN
.
PICKUP
(
I
2
Z
)
ONLY
t
(
AMPS
)
UP
UP
UP
0.5
12.7
11.5
17.1
1.0
3.18
2.87
4.28
LOW
9.6
8.7
8.2
2.40
2.18
2.04
427.5
107.0
0.5
-
4.0
HIGH
1.05
LOW
2.0
0.76
0.72
0.189
0.180
0.261
0.147
0.133
0.125
0.59
0.53
0.50
26.25
2.0
-
16.0
HIGH
4.0
6.63
10.0
LOW
0.042
0.029
0.051
0.029
0.026
0.024
0.010
0.007
0.013
0.007
0.007
0.006
1.28
10.0
-
80.0
HIGH
20.0
0.33
0.015
0.008
0.017
0.010
0.009
0.008
0.004
0.002
0.004
0.002
0.002
0.002
LOW
20.0
0.43
20.0
-
160.0
HIGH
40.0
0.10
t
Low
means
two
windings
connected
in
series
.
High
means
two
windings
connected
in
parallel
.
See
Internal
-
Connections
diagram
for
additional
information
.
CHARACTERISTICS
Pickup
of
these
relays
is
defined
as
the
current
required
to
close
the
contacts
from
the
0.5
time
-
dial
position
.
The
pickup
value
of
the
IAC
77
relays
is
within
3
%
of
the
tap
value
.
The
setting
of
the
time
dial
determines
the
length
of
time
the
unit
requires
to
close
its
contacts
when
the
current
reaches
the
predetermined
value
.
The
contacts
are
just
closed
when
the
dial
is
set
at
zero
.
When
the
dial
is
set
at
10
,
the
disk
must
travel
the
maximum
distance
to
close
the
contacts
;
this
gives
the
maximum
time
setting
.
The
unit
resets
at
85
%
of
the
minimum
closing
value
of
current
.
Figure
9
shows
the
50
-
Hz
and
Figure
10
shows
the
60
-
Hz
Time
/
Current
Characteristics
for
Relay
types
IAC
77
and
IAC
78
.
The
time
to
reset
to
the
10
time
-
dial
position
when
the
current
is
reduced
to
zero
is
approximately
57
seconds
.
The
time
/
current
curve
for
the
instantaneous
unit
is
shown
on
Figure
8
.
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
9
Courtesy of NationalSwitchgear.com
GEK
-
34055
sustained
in
transit
,
handling
is
evident
,
transportation
company
and
promptly
notify
Electric
Sales
Office
.
If
injury
or
damage
resulting
from
rough
file
a
damage
claim
at
once
with
the
the
nearest
General
Reasonable
care
should
be
exercised
in
unpacking
the
relay
in
order
that
none
of
the
parts
are
injured
nor
the
adjustments
disturbed
.
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
.
ACCEPTANCE
TESTS
Immediately
upon
receipt
of
the
relay
,
an
INSPECTION
AND
ACCEPTANCE
TEST
should
be
made
to
make
sure
that
no
damage
has
been
sustained
in
shipment
and
that
the
relay
calibrations
have
not
been
disturbed
.
If
the
examination
or
test
indicates
that
readjustment
is
necessary
,
refer
to
the
section
on
SERVICING
.
These
tests
may
be
performed
as
part
of
the
installation
or
as
acceptance
tests
,
at
the
discretion
of
the
user
,
operating
companies
use
different
procedures
for
acceptance
and
for
installation
tests
,
the
following
section
includes
all
applicable
tests
that
may
be
performed
on
these
relays
.
Since
most
VISUAL
INSPECTION
Check
the
nameplate
stamping
to
make
sure
that
the
model
number
and
rating
of
the
relay
agree
with
the
requisition
.
Remove
the
relay
from
its
case
and
check
that
there
are
no
broken
or
cracked
molded
parts
or
other
signs
of
physical
damage
,
and
that
all
the
screws
are
tight
.
MECHANICAL
INSPECTION
There
should
be
no
noticeable
friction
when
the
disk
is
rotated
slowly
clockwise
.
The
disk
should
return
by
itself
to
its
rest
position
.
1
.
Make
sure
the
control
spring
is
not
deformed
,
nor
its
convolutions
tangled
or
touching
.
2
.
The
armature
and
contacts
of
the
seal
-
in
unit
,
as
well
as
the
armature
and
contacts
of
the
instantaneous
unit
,
should
move
freely
when
operated
by
hand
;
there
should
be
at
least
1
/
32
"
wipe
on
the
seal
-
in
contacts
.
3
.
4
.
The
targets
in
the
seal
-
in
unit
and
in
the
instantaneous
unit
must
come
into
view
and
latch
when
the
armatures
are
operated
by
hand
,
and
should
unlatch
when
the
target
release
lever
is
operated
.
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Courtesy of NationalSwitchgear.com
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Make
sure
that
the
fingers
and
shorting
bars
agree
with
the
internal
-
connections
diagram
.
5
.
CAUTION
Every
circuit
in
the
drawout
case
has
an
auxiliary
brush
.
It
is
especially
important
on
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
.
circuits
from
being
opened
.
This
will
prevent
ct
secondary
See
Figure
1
.
ELECTRICAL
TESTS
DRAWOUT
RELAYS
,
GENERAL
Since
all
drawout
relays
in
service
operate
in
their
cases
,
it
is
recommended
that
they
be
tested
in
their
cases
or
an
equivalent
steel
In
this
way
,
any
magnetic
effects
of
the
enclosure
will
be
A
relay
may
be
tested
without
This
plug
any
The
12
XLA
12
A
test
plug
may
also
be
used
,
test
plug
allows
greater
testing
flexibility
,
it
shorting
jumpers
and
the
exercise
of
greater
care
,
are
made
to
both
the
relay
and
the
external
case
.
accurately
duplicated
during
testing
.
removing
it
from
the
panel
by
using
a
12
XLA
13
A
test
plug
,
makes
connections
only
with
the
relay
and
does
not
disturb
shorting
bars
in
the
case
.
Although
this
requires
C
.
T
.
since
connections
circuitry
.
POWER
REQUIREMENTS
,
GENERAL
All
devices
operating
on
alternating
current
(
AC
)
are
affected
by
frequency
.
fundamental
frequency
plus
harmonics
of
that
fundamental
frequency
,
it
follows
that
alternating
-
current
devices
(
relays
)
will
be
affected
AC
relays
(
and
AC
devices
in
general
)
are
the
application
of
non
-
sinusoidal
Since
non
-
sinusoidal
waveforms
can
be
analyzed
as
a
by
applied
waveforms
,
significantly
affected
by
waveforms
.
Therefore
,
in
order
to
test
AC
relays
properly
it
is
essential
to
use
a
test
voltage
and
/
or
current
waveform
that
is
sinusoidal
,
purity
of
the
sine
wave
(
i
.
e
expressed
as
a
finite
number
for
any
particular
relay
;
however
,
any
relay
using
tuned
circuits
,
RL
or
RC
networks
,
or
saturating
electromagnets
(
such
as
time
-
overcurrent
relays
)
would
be
especially
affected
by
non
-
sinusoidal
wave
forms
.
The
its
freedom
from
harmonics
)
cannot
be
•
r
TIME
-
OVERCURRENT
UNIT
Rotate
the
time
dial
slowly
and
check
,
by
means
of
a
lamp
in
the
circuit
,
that
the
contacts
just
close
at
the
zero
(
0
)
time
-
dial
setting
.
The
point
at
which
the
contacts
just
close
can
be
adjusted
by
running
the
stationary
contact
brush
in
or
out
by
means
of
its
adjusting
screw
.
This
screw
should
be
held
securely
in
its
support
.
11
Courtesy of NationalSwitchgear.com
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With
the
contacts
just
closing
at
No
.
0
time
-
dial
setting
,
there
should
be
sufficient
gap
between
the
stationary
contact
brush
and
its
metal
backing
strip
to
ensure
approximately
1
/
32
"
wipe
.
The
minimum
current
at
which
the
contact
will
just
close
is
determined
by
the
position
of
the
tap
screw
in
the
tap
block
at
the
top
of
the
relay
.
When
changing
the
current
setting
with
the
relay
in
its
case
,
remove
the
connection
plug
,
to
short
the
current
transformer
(
CT
)
secondary
circuit
.
Next
,
screw
the
tap
screws
into
the
tap
marked
for
the
desired
current
,
and
then
replace
the
connection
plug
.
The
pickup
of
the
unit
for
any
current
tap
setting
is
adjusted
by
means
of
the
variable
resistor
in
the
phase
-
shifting
circuit
.
This
adjustment
also
permits
any
desired
setting
intermediate
between
the
various
tap
settings
to
be
obtained
.
The
control
spring
is
prewound
approximately
660
°
with
the
contacts
just
closed
.
Further
adjustment
of
this
setting
is
seldom
required
.
The
unit
is
adjusted
at
the
factory
to
close
its
contacts
from
any
time
-
dial
position
at
a
minimum
current
within
5
%
of
the
tap
setting
.
The
unit
resets
at
85
%
of
the
minimum
closing
value
,
Pickup
Test
Set
the
relay
at
the
0.5
time
-
dial
position
and
2.0
amp
tap
.
Using
the
test
connections
of
Figure
13
,
the
main
unit
should
close
its
contacts
within
±
2
%
of
tap
value
current
(
1.96
-
2.04
amp
.
)
,
other
tap
positions
should
pick
up
at
tap
value
±
5
%
of
tap
value
.
All
Time
Test
*
Set
the
relay
at
the
5.0
time
-
dial
position
and
2.0
amp
tap
.
Using
the
test
connections
of
Figure
13
,
and
applying
5
times
tap
current
(
10.0
amp
)
,
the
relay
should
operate
in
0.92
second
±
0.05
second
.
At
2
times
tap
current
and
10
times
tap
current
,
the
operating
time
should
agree
with
the
time
-
curve
value
±
7
%
.
INSTANTANEOUS
UNIT
Make
sure
that
the
instantaneous
unit
is
wired
for
the
range
in
which
it
is
to
operate
(
see
Internal
-
Connections
Diagram
Figure
5
or
Figure
7
)
and
connected
as
indicated
in
Test
-
Circuit
Figure
13
.
Whenever
possible
,
use
the
higher
range
,
since
the
higher
range
has
a
higher
continuous
rating
.
Setting
the
Instantaneous
Unit
Loosen
the
locknut
and
turn
the
pole
piece
toward
the
desired
Turning
the
pole
piece
up
increases
the
setting
.
pickup
;
turning
the
pole
piece
down
decreases
the
pickup
.
Bring
up
the
current
slowly
until
the
unit
picks
up
.
repeat
this
operation
until
the
desired
pickup
value
is
obtained
.
Once
the
desired
pickup
value
is
reached
,
tighten
the
locknut
.
See
Figure
2
.
It
may
be
necessary
to
*
Indicates
revision
12
Courtesy of NationalSwitchgear.com
GEK
-
34055
CAUTION
The
instantaneous
unit
is
rated
1.5
times
minimum
pickup
,
leave
the
test
current
on
too
long
,
as
it
may
damage
the
unit
.
Do
not
Pickup
Tests
With
the
unit
connected
for
high
-
range
operation
(
parallel
connections
)
and
the
target
in
the
"
Down
"
position
,
check
the
pickup
at
the
maximum
calibration
mark
;
the
pickup
should
be
within
the
limits
in
Table
X
.
TABLE
X
UNIT
RANGE
AMPERES
CALIBRATION
AMPERES
MINIMUM
AMPERES
MAXIMUM
AMPERES
0.5
-
4.0
3.6
4.0
4.5
2.0
-
16.0
14.4
16.0
17.7
10.0
-
80.0
72.0
80.0
89.0
20.0
-
160.0
144.0
160.0
177.0
TARGET
AND
SEAL
-
IN
UNIT
The
target
and
seal
-
in
unit
has
an
operating
coil
tapped
at
0.2
and
2.0
amperes
.
The
relay
is
shipped
from
the
factory
with
the
tap
screw
in
the
lower
-
ampere
position
,
holding
the
right
-
hand
stationary
setting
,
and
place
it
in
the
desired
tap
.
first
,
The
tap
screw
is
the
contact
.
screw
To
change
the
tap
first
remove
one
screw
from
the
left
-
hand
stationary
contact
Next
,
remove
the
screw
from
the
undesired
,
tap
and
place
it
on
the
left
hand
stationary
contact
where
the
first
screw
was
removed
.
See
Figure
2
.
This
procedure
is
necessary
to
prevent
the
right
-
hand
stationary
contact
from
getting
out
of
adjustment
.
Screws
should
never
be
left
in
both
taps
at
the
same
time
.
Pickup
and
Dropout
Test
Connect
relay
studs
1
and
2
(
See
Internal
-
Connections
Diagram
)
to
a
DC
source
,
ammeter
and
load
box
so
that
the
current
can
be
controlled
over
a
range
of
0.1
to
2.0
amperes
.
1
.
Turn
the
time
dial
to
the
ZERO
(
0
)
TIME
-
DIAL
position
.
2
.
Increase
the
current
slowly
until
the
seal
-
in
unit
picks
up
.
Table
XI
.
3
.
See
Move
the
time
dial
away
from
the
ZERO
(
0
)
TIME
-
DIAL
position
,
the
seal
-
in
unit
should
remain
in
the
picked
-
up
position
.
4
.
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Courtesy of NationalSwitchgear.com
GEK
-
34055
5
.
Decrease
the
current
slowly
until
the
seal
-
in
unit
drops
out
.
See
Table
XI
.
TABLE
XI
PICK
-
UP
CURRENT
DROPOUT
CURRENT
TAP
0.14
-
0.195
.
050
OR
MORE
1.40
-
1.95
.
50
OR
MORE
0.2
2.0
INSTALLATION
The
following
tests
are
to
be
performed
at
the
time
of
installation
.
TIME
-
OVERCURRENT
UNIT
1
.
Set
the
tap
screw
in
the
desired
tap
.
Figure
13
,
apply
approximately
twice
tap
value
until
contacts
just
close
.
the
contacts
begins
to
flicker
.
as
pickup
,
and
should
be
within
5
%
of
tap
value
.
Using
the
test
circuit
in
Reduce
the
current
until
the
light
in
series
with
This
value
of
current
is
defined
*
2
.
Check
the
operating
time
at
Time
Dial
times
the
tap
current
,
shown
on
the
time
/
current
curve
±
7
%
.
2
,
and
I
5
,
TAP
The
operating
time
should
be
the
time
5
TARGET
AND
SEAL
-
IN
UNIT
1
.
Make
sure
that
the
tap
screw
is
in
the
desired
tap
.
Perform
pickup
and
dropout
tests
,
as
outlined
in
the
ACCEPTANCE
TESTS
section
.
2
.
INSTANTANEOUS
UNIT
1
.
Select
the
desired
range
by
making
the
proper
connections
at
the
Whenever
since
it
has
a
rear
of
the
relay
(
See
Internal
-
Connections
Diagram
)
,
possible
,
be
sure
to
select
the
higher
range
,
higher
continuous
rating
.
2
.
Set
the
level
.
TESTS
section
.
instantaneous
unit
to
pick
up
at
the
desired
current
See
Setting
the
Instantaneous
Unit
,
in
the
ACCEPTANCE
All
the
tests
described
above
under
Installation
Tests
must
be
In
addition
,
if
those
tests
performed
at
the
time
of
installation
,
described
under
the
ACCEPTANCE
TESTS
section
were
not
performed
prior
to
installation
,
it
is
recommended
that
they
be
performed
at
this
time
.
*
Indicates
revision
14
Courtesy of NationalSwitchgear.com
GEK
-
34055
PERIODIC
CHECKS
AND
ROUTINE
MAINTENANCE
In
view
of
the
vital
role
of
protective
relays
in
the
operation
of
a
power
system
,
it
is
important
that
a
periodic
test
program
be
followed
.
It
is
recognized
that
the
interval
between
periodic
checks
will
vary
depending
upon
environment
,
type
of
relay
and
the
user
'
s
experience
with
periodic
testing
.
Until
the
user
has
accumulated
enough
experience
to
select
the
test
interval
best
suited
to
his
individual
requirements
,
it
is
suggested
that
the
points
listed
below
be
checked
at
an
interval
of
from
one
to
two
years
.
These
tests
are
intended
to
make
sure
that
the
relays
have
not
deviated
from
their
original
setting
.
the
relay
must
be
retested
and
serviced
as
described
in
this
manual
.
If
deviations
are
encountered
,
TIME
-
OVERCURRENT
UNIT
Perform
the
Pickup
Test
as
described
in
the
ACCEPTANCE
TESTS
section
for
the
tap
in
service
.
1
.
Perform
the
Time
Test
as
described
in
the
ACCEPTANCE
TESTS
section
.
2
.
INSTANTANEOUS
UNIT
Check
that
the
Instantaneous
Unit
picks
up
at
the
desired
current
level
,
as
outlined
in
the
ACCEPTANCE
TESTS
section
.
1
.
TARGET
AND
SEAL
-
IN
UNIT
Check
that
the
unit
picks
up
at
the
values
shown
in
Table
XI
.
1
.
Check
that
the
units
drops
out
at
30
%
or
more
of
tap
value
.
2
.
CONTACT
CLEANING
For
cleaning
relay
contacts
,
a
flexible
burnishing
tool
should
be
This
consists
of
a
flexible
strip
of
metal
with
an
etch
-
roughened
surface
,
resembling
in
effect
a
superfine
file
,
polishing
action
is
so
delicate
that
no
scratched
are
left
,
will
clean
off
any
corrosion
thoroughly
and
rapidly
,
ensures
the
cleaning
of
the
actual
points
of
contact
,
knives
,
files
,
contacts
.
used
.
The
yet
it
Its
flexibility
Do
not
use
abrasive
paper
or
cloth
of
any
kind
to
clean
relay
SYSTEM
TEST
Although
this
Instruction
Book
is
primarily
written
to
check
and
set
the
I
AC
relay
,
overall
functional
tests
to
check
the
system
operation
are
recommended
at
intervals
based
on
the
customer
'
s
experience
.
15
Courtesy of NationalSwitchgear.com
GEK
-
34055
SERVICING
TIME
-
OVERCURRENT
UNIT
If
it
is
found
during
installation
or
periodic
testing
that
the
time
overcurrent
unit
is
out
of
limits
,
the
unit
may
be
recalibrated
as
follows
:
Rotate
the
time
dial
to
the
No
.
O
time
-
dial
setting
and
check
,
by
means
of
a
lamp
in
the
circuit
,
that
the
contacts
just
close
.
The
point
at
which
the
contacts
just
close
can
be
adjusted
by
running
the
stationary
contact
brush
in
or
out
by
means
of
its
adjusting
screw
,
support
.
With
the
contacts
just
closing
at
No
.
O
time
-
dial
setting
,
there
should
be
sufficient
gap
between
the
stationary
contact
brush
and
its
metal
backing
strip
to
ensure
approximately
1
/
32
"
wipe
.
Connect
the
operating
-
coil
terminals
to
a
source
of
the
proper
frequency
and
good
waveform
having
a
voltage
of
120
or
more
,
with
pure
resistance
load
boxes
for
setting
the
current
,
circuit
,
Figure
13
.
1
.
This
screw
should
be
held
securely
in
its
2
.
See
test
Set
the
tap
plug
in
the
2
amp
.
tap
,
and
the
time
dial
where
the
contacts
are
just
open
.
Set
the
resistor
at
the
midpoint
of
its
range
and
check
the
current
required
to
just
close
the
contacts
.
It
should
fall
within
the
limits
given
in
Table
XII
.
3
.
TABLE
XII
TAP
RANGE
TAP
MINIMUM
AMPS
MAXIMUM
AMPS
0.5
-
4.0
1.96
2
AMP
2.04
1.5
-
12.0
1.96
2
AMP
2.04
2.0
-
15.0
1.96
2
AMP
2.04
It
should
never
be
necessary
to
wind
up
the
control
-
spring
adjustor
more
than
30
°
(
one
notch
)
or
unwind
it
more
than
90
°
(
three
notches
)
from
the
factory
setting
to
obtain
the
above
pickup
setting
.
4
.
After
pick
up
has
been
set
within
the
prescribed
limits
,
the
compensation
must
be
checked
.
With
the
2
amp
tap
setting
as
in
paragraph
3
,
set
the
time
dial
at
No
.
10
and
check
the
current
required
to
just
move
the
disk
away
from
the
stop
arm
.
This
current
should
be
within
the
limits
shown
in
Table
XIII
,
which
are
±
6
%
of
tap
amperes
.
If
the
disc
moves
at
the
lower
limit
,
check
that
the
movement
is
not
over
1
/
2
"
,
measured
along
the
periphery
of
the
disc
.
16
Courtesy of NationalSwitchgear.com
GEK
-
34055
TABLE
XIII
TAP
RANGE
TAP
MINIMUM
AMPS
MAXIMUM
AMPS
1.88
0.5
-
4.0
2.12
2
AMP
1.5
-
12.0
1.88
2
AMP
2.12
2.0
-
15.0
1.88
2.12
2
AMP
If
the
current
falls
outside
these
limits
,
the
following
steps
should
be
taken
.
#
10
time
dial
setting
(
TDS
)
Then
set
at
#
1
/
2
T
.
D
.
S
.
and
restore
pick
up
by
adjusting
the
resistor
.
adjustment
.
Reset
the
control
spring
until
compensation
at
is
within
the
limits
shown
above
.
Compensation
should
be
rechecked
after
the
resistor
With
the
contacts
just
open
,
check
the
current
required
to
just
close
the
contacts
on
each
of
the
other
taps
,
should
be
within
±
3
%
of
tap
value
.
This
current
With
the
time
dial
at
the
No
.
10
time
setting
and
the
tap
plug
in
the
2
amp
tap
,
apply
sufficient
current
to
the
relay
to
definitely
close
the
contacts
.
Reduce
the
current
to
80
%
of
tap
value
and
the
disk
should
reset
all
the
way
to
the
No
.
10
dial
setting
position
.
Time
Tests
With
the
tap
plug
in
the
2
amp
tap
and
the
time
dial
at
No
.
5
time
setting
,
apply
five
times
(
5
X
)
tap
current
to
the
relay
.
Adjust
the
drag
magnet
to
obtain
a
closing
time
as
near
as
possible
to
0.92
second
but
at
least
between
0.87
and
0.97
second
.
The
magnet
should
be
approximately
in
the
middle
of
its
travel
,
magnet
is
adjusted
by
loosening
the
nut
under
the
magnet
shelf
.
Moving
the
magnet
in
decreases
the
time
,
moving
the
magnet
out
increases
the
time
.
The
When
adjusting
the
drag
magnet
,
be
sure
the
outer
edge
of
the
magnet
never
extends
out
beyond
the
cutout
in
the
disk
.
Be
sure
the
nut
clamping
the
drag
magnet
to
its
supporting
shelf
is
tight
before
proceeding
with
other
time
checks
.
Make
sure
the
drag
magnet
does
not
hit
the
counterweight
at
any
position
of
the
disk
.
With
the
tap
plug
in
the
2
amp
tap
and
the
time
dial
at
the
No
.
5
time
setting
,
check
the
contact
closings
at
2
times
and
10
times
tap
value
.
XIV
.
These
closing
times
must
be
within
the
limits
shown
in
Table
TABLE
XIV
60
HZ
50
HZ
TAP
AMPS
MIN
SEC
.
MAX
SEC
.
MIN
.
SEC
.
MAX
SEC
.
2.0
4.0
6.27
7.22
6.58
7.56
2.0
20.0
0.26
0.30
0.27
0.31
17
Courtesy of NationalSwitchgear.com
GEK
-
34055
INSTANTANEOUS
UNIT
1
.
Both
contacts
should
close
at
the
same
time
.
The
backing
strip
should
be
so
formed
that
the
forked
end
(
front
)
bears
against
the
molded
strip
under
the
armature
.
With
the
armature
against
the
pole
piece
,
the
cross
member
of
the
"
T
"
spring
should
be
in
a
horizontal
plane
and
there
should
be
at
least
1
/
32
inch
wipe
on
the
contacts
.
Check
this
by
inserting
a
0.012
inch
feeler
gage
between
the
front
half
of
the
shaded
pole
and
the
armature
,
with
the
armature
held
closed
.
The
contacts
should
close
with
the
feeler
gage
in
place
.
2
.
3
.
TARGET
AND
SEAL
-
IN
UNIT
Check
steps
1
and
2
as
described
under
INSTANTANEOUS
UNIT
above
.
To
check
the
wipe
of
the
seal
-
in
unit
,
insert
a
0.012
inch
feeler
gage
between
the
plastic
resid
al
of
the
armature
and
the
pole
with
the
armature
held
closec
.
feeler
gage
in
place
.
piece
The
contacts
should
close
with
the
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
Company
,
specify
the
quantity
required
and
the
name
of
the
part
wanted
,
and
the
complete
model
number
of
the
relay
for
which
the
part
is
required
.
18
Courtesy of NationalSwitchgear.com
r
.
_
>
4055
LIST
OF
FIGURES
PAGE
FIGURE
Cross
Section
of
Drawout
Case
Showing
Position
of
Auxiliary
Brush
1
20
Type
-
IAC
77
800
Series
Relay
Removed
from
Case
(
Front
View
)
2
21
Type
-
IAC
77
800
Series
Relay
Removed
from
Case
(
Rear
View
)
3
22
Type
-
IAC
77
A
800
Series
Relay
Internal
Connections
(
Front
View
)
4
23
Type
-
IAC
77
B
800
Series
Relay
Internal
Connections
(
Front
View
)
5
24
Type
-
IAC
78
A
800
Series
Relay
Internal
Connections
(
Front
View
)
6
25
Type
-
IAC
78
B
800
Series
Relay
Internal
Connections
(
Front
View
)
7
26
Time
/
Current
Curve
of
the
Instantaneous
Unit
.
.
27
8
Time
/
Current
Characteristics
of
50
Hz
Types
IAC
77
and
IAC
78
800
Series
Relays
9
28
Time
/
Current
Characteristics
of
60
Hz
Types
IAC
77
and
IAC
78
800
Series
Relays
10
29
Outline
and
Panel
Drilling
for
the
IAC
78
B
Series
Relay
30
11
Outline
and
Panel
Drilling
for
Types
IAC
77
A
,
IAC
77
B
and
IAC
78
A
800
Series
Relays
...
.
12
31
Test
connections
for
Testing
Pickup
and
Time
Curve
of
IAC
Relays
13
32
External
Connections
of
Four
IAC
77
A
Relays
Used
for
Multi
-
Phase
and
Phase
-
to
-
Ground
Fault
Protection
of
a
3
-
Phase
Circuit
14
33
External
Connections
of
Four
IAC
78
A
Relays
Protecting
a
3
-
Phase
Circuit
Against
Multi
-
Phase
and
Phase
-
to
-
Ground
Faults
15
34
19
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Table of contents
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