GE IAC77A User manual

GEK-34055F
TYPES
INSTRUCTIONS
TIME
OVERCURRENT
RELAYS
IAC77A
FORM
800
AND
UP
IAC77B
FORM
800
AND
UP
IAC78A
FORM
800
AND
UP
IAC]8B
FORM
800
AND
UP
GENERAL
ELECTRIC

GEK-34055
TABLE
OF
CONTENTS
PAGE
DESCRIPTION
APPLICATION
CONSTRUCTION
RATINGS
TIME-OVERCURRENT
UNIT
INSTANTANEOUS
UNIT
TARGET
AND
SEAL-IN
UNIT
CONTACTS
BURDENS
CHARACTERISTICS
RECEIVING,
HANDLING,
AND
STORAGE
ACCEPTANCE
TESTS
VISUAL
INSPECTION
MECHANICAL
INSPECTION
ELECTRICAL
TESTS
DRAWOtJT
RELAYS
GENERAL
POWER
REQUIREMENTS
GENERAL
TIME—OVERCURRENT
UNIT
PICKUP
TEST
TIME
TEST
INSTANTANEOUS
UNIT
SETTING
THE
INSTANTANEOUS
PICK
UP
TESTS
TARGET
AND
SEAL-IN
UNIT
PICK-UP
AND
DROPOUT
TEST
INSTALLATION
TIME-OVERCURRENT
UNIT
TARGET
AND
SEAL-IN
UNIT
INSTANTANEOUS
UNIT
PERIODIC
CHECKS
AND
ROUTINE
MAINTENANCE
TIME
OVERCURRENT
UNIT
INSTANTANEOUS
UNIT
TARGET
AND
SEAL-IN
UNIT
CONTACT
CLEANING
SYSTEM
TEST
SERVICING
TIME-OVERCIJRRENT
UNIT
TIME
TESTS
INSTANTANEOUS
UNIT
TARGET
AND
SEAL-IN
UNIT
RENEWAL
PARTS
3 4 4 5 5 6 7 8 8 9 9 10 10 10 11 11 11 11 12 12 12 12 13 13 13 14 14 14 14 15 15 15 15 15 15 16 16 17 18 18 18
(Cover
photo
8041299)
UNIT
2

GEK-34055
TIME
OVERCURRENT
RELAYS
TYPES
IAC77A,
77B,
78A, 78B
FORM
800
and
UP
DESCRIPTION
‘ype
1AC77 and
1AC78
relays
are
single—phase,
current—operated,
AC
de
.ces 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
1.
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.
A
standard
Sl
case
is
used
to
mount
each
relay.
The
outline
and
mounting
dimensions
of
this
case
are
shown
in
Figures
11
and
12.
The
basic
differences
between
the
relays
covered
by
these
instructions
are
noted
in
the
following
Table I.
TABLE
I
INSTANTANEOUS
CONTACT
INTERNAL
TYPE
UNIT
CIRCUITS
CONNECTIONS
IAC77A
NO
1
FIGURE
4
IAC77B
YES
1
FIGURE
5
IAC78A
NO
2
FIGURE 6
IAC78B
YES
2
FIGURE
7
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
rnuintenunce.
Should
further
injhrmation
he
desired
or
should
particular
pro
hiems
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

GEK-34055
APPLICATION
The
extremely
inverse
time/current
characteristics
make
the
1AC77
and
1AC78
relays
particularly
well
suited
for
the
protection
of
primary
distribution
circuits.
In
such
applications,
because
the
relay
characteristics
closely
parallel
those
of
the
power
fuses
normally
employed
in
these
circuits,
it
is
possible
to
obtain
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
1AC77
and
IAC78
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’s
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.
The
disk
shaft
carries
the
moving
contact, which
completes
the
trip
or
alarm
circuit.
The
disk
shaft
is restrained
by
a
spiral
spring
to give
proper
contact—closing
4

GEK-34055
current,
and
its
motion
is
retarded
by
a
permanent
magnet
acting
on
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.
When
the
instantaneous unit
picks
up
it
raises
a
target,
which
latches
up
and
remains
exposed
until
it
is
released.
The
same
button
that
releases
the
target
of
the
seal—in
unit
also
releases
the
target
of
the
instantaneous
unit.
RATINGS
TIME-OVERCURRENT
UNIT
Ratings
of
the
time—overcurrent
unit
are
given in Table
II.
TPBLE
II
PICK
UP RANGE.
AMPERES
RELAY
FREQUENCY
MAIN
(TIME)
INSTANTANEOUS
CYCLES
UNIT
UNIT
IAC77A
and
50
0.5
-
4.0
IAC78A
60
IAC77B
and
50
0.5 -
4.0
0.5
-
4.0
IAC78B
60
1.5
-
12.0
2.0
-
16.0
2.0
-
15.0 10.0
-
80.0
20.0
-
160.0
Available
taps
of
the
time—overcurrent
unit
are
shown on
Table
III.
TABLE
III
RANGE,
AMPERES
TAPS
AVAILABLE
(AMPERES)
0.5
-
4.0
0.5,
0.6,
0.7,
0.8
1.0,
1.?,
1.5,
2.0,
2.5,
3.0,
4.0
1.5
—
12.0
1.5, 2.0, 2.5,
3.0, 4.0,
5.0,
6.0,
7.0,
8.0,
10.0,
12.0
2.0 —
15.0
2.0,
2.5,
3.0,
4.0,
5.0,
6.0, 7.0,
8.0,
10.0,
12.0,
15.0
The
one—second
thermal
ratings
are
listed
in
Table
IV.
5

GE K-340
55
TABLE
IV
TIME
OVERCURRENT
UNIT
ONE
SECOND
K
(AMPS)
RATING(AMPS)
0.5 - 4.0
125.0
15,625
1.5
-
12.0
260.0
67,600
2.0
- 15.0 260.0
67,600
For ratings
of
less than one
second, the
rating
may be
calculated
according
to
the formula
1=4
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
[\TING
3.5 3.7
4.0 4.5
5.0 5.5
6.0 7.0
8.0
9.0
10.0
1.5- 12.0
AMP RANGE
TAP 1.5
2.0
2.5
3.0 4.0
5.0
6.0
7.0
8.0
10.0 12.0
RATING 9.5
10.5
11.5 12.5
14.0 15.5
17.0
18.0 19.0
20.0 20.0
2.0-
1 5.0 AMP RANGE
TAP
2.0 2.5
3.0
4.0
50
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
either one
of
two
ranges.
Any
setting
obtained
in
the
lower range
(series
connected) is
doubled,
within
±3%,
when
the unit
is connected
for
high—range
operation
(parallel
connected).
6

GE
K-340
55
The
instantaneous
unit
has
a
continuous
rating
of
1.5 times
minimum
setting
or
25
amperes,
whichever
is
smaller.
Example:
The
2.0—16.0
ampere instantaneous
unit,
when
set
on
the
low
range
(2.0—
8.0
amperes)
has
a
continuous
rating
of
3.0
amperes,
and
when
connected
for
high-range
operation
(4.0—16.0
amperes)
has
a
continuous
rating
of
6.0 amperes.
The
continuous
and
one—second
ratings
for
the
instantaneous
unit
are
shown
in Table
VI.
TABLE
VI
RANGE
CONNECT—
CONTINUOUS
t
ONE
K
IONS
tt
RATING
SECOND
0.5
-
4.0 0.5
—
2.0
S 0.15 25.0
625
1.0
-
4.0
P
1.5 50.0
2,500
2.0
-
16.0 2.0
-
8.0
S 3.0
130.0
16,900
4.0
- 16.0 p
6.0
260.0 67,600
10.0
-
80.0
10.0
-
40.0
S 15.0
400.0
160,000
20.0
-
80.0
P
25.0
600.0
360,000
20.0
-
160.0 20.0
- 80.0
S
25.0
600.0
360,000
40.0
-
160.0
P
25.0 600.0
360,000
t
Higher
currents
may
be
applied
for
shorter
lengths
of
time
in
accordance
with
the
formula
K
where
T
is
the
time,
in
seconds,
that
the
current
flows.
t
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)
7
0.13
MIN.
Operating (amperes)
+0 -
25%
0.2 2.0
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

GEK-34055
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—overcurrent
unit
are
given
in
Table
VIII.
TABLE
VIII
BURDENS
AT
MIN.
BURDENS IN
PICKUP
MIN. TAP
OHMS
(1)
V.A.
AT
5
AMPS
RANGE
HZ
MIN.
R
Z
3 10
20.0
CALCULATED
FROM
TAP
TIMESTIMESTIMES
IMPEDANCE
AT
MIN.
PICK-
PICK- PICK-
PICKUP
(121)
tip
LIP
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
NOTE:
The
impedance
values
given
are
those
for
the
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,
for
a
relay
with 0.5
—
4.0
amp
range,
the
impedance
of
the
0.5 amp
tap
is
given
as
1.60
ohms.
The
impedance
of
the
2.0
amp
tap
at
2.0
amperes
is
(.5/2)2
x
1.6 or 0.10
ohm.
8

GEK-34055
The
instantaneous
unit
burdens
are
listed
in
Table
IX.
TABLE
IX
BURDENS
AT
MIN.
BURDENS
IN
RANGE
PICKUP
MIN.
TAP
OHMS
(Z)
RELAYS
TIONS
AMPS
R
Jx
Z
3
10
20.0
V.A.
AT
5AMPS
ONLY
t
OHMS OHMS OHMS
TIMES
TIMES
TIMES
CALCULATED
FROM
(AMPS)
PICK
PICK PICK
IMPEDANCE
AT MIN.
UP
UP
UP
PICKUP
(I?Z)
O
5-4 0
LOW
0.5
12.1 11.5 17.1
9.6 8.7
8.2
427.5
HIGH
1.0 3.18
2.87
4.28
2.40
2.18
2.04
107.0
2
0-16
0
LOW
2.0
0.76 0.72
1.05
O.5
0.53
0.50
26.25
HIGH
4.0
0.189
0.180
0.261
0.147
0.133
0.125
6.63
10
0-80
0
LOW
10.0
0.042 0.029 0.051 0.029
0.026
0.024 1.28
HIGH
20.0
0.010
0.007
0.013 0.007
0.001
0.006
0.33
20
0-160
0
LOW
20.0
0.015
0.008
0.017
0.010 0.009 0.008
0.43
HIGH
40.0
0.004
0.002 0.004 0.002
0.002
0.002
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
1AC77
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
1AC77
and
1AC78.
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

GEK-34055
sustained
in
transit.
If
injury
or
damage
resulting
from
rough
handling
is
evident,
file a
damage
claim
at
once
with
the
transportation
company
and
promptly
notify
the
nearest
General
Electric
Sales
Office.
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.
Since
most
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.
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
1.
There
should
be
no
noticeable
friction
when
the
disk
is
rotated
slowly
clockwise.
The
disk
should
return
by
itself
to
its
rest
position.
2.
Make sure
the
control
spring
is
not deformed,
nor
its
convolutions
tangled
or
touching.
3.
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.
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.
10