Time-Overcurrent - GE IAC60A Instructions Manual

TIME-OVERCURRENT

Contact
Type
Circuits
IAC51A(-)A
IAC51B(-)A
IAC51R(-) A
IAC52A(-)A
IAC52B(-)A
The Type lAC relays comprise a group of relays
that are employed to protect against overcurrent on
single-phase and polyphase circuits.
relays in this lAC 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
INTRODUCTION
The induction unit is the basic unit in all lAC
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.
shaft carries the moving contact which completes
the alarm or trip circuit when it touches the station­
ary contact or contacts.
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.
series and its contacts in parallel with the main
contacts such that when the main contacts close the
seal-in unit picks up
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.
These instructions do not purport
evt'ry possillle c ontingenc y to be met in connection with installation,
furt.'Jer fo ma i o
r n be desired or should particular problems arise which are not covered sufficiently for
in t
the purchaser's purposes,
To
the extent req
such ss r
no a u a
n c e
but
TYPE lAC
INTRODUCTION
Instantaneous
Unit
One
NG
One
Yes
One
Yes
Tw o
No
Tw o
Yes
The various
instantaneous unit which
INDUCTION UNIT
The disk
The disk shaft is restrained
This unit has its coil in
and seals in. When the
to cover all details or variations in equipment nor to provide for
t h e matter should be referred to the General
u rodu s
t
ire d c described herein meet applicable ANSI,
the p
is gi
v
e n with respect to local
RELAYS
AC Trip Induction
Unit Unit
No One
One
No
One
Ye s
One
No
One
No
permits instantaneous tripping for extremely high
currents, or an induction unit with an a-c tripping
unit for use where d-e power is unavailable or a-c
tripping is preferred.
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.
APPLICATION
The induction unit is the main unit in all lAC
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.
OPERATING
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
The induction element is designed to use any
one of three operating coils, each having a different
combination of taps as follows:
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.
operation or maintenance.
Electric
codes a nd ordinances because they vary greatly.
&
Outline
Internal
Panel Drilling Connection
Fig. 11
Fig. 18
Fig.
ig
18
F
.
Fig. 13
Fig. 18
Fig. 18 Fig. 14
Fig. 18 Fig. 15
Since practically all lAC
CHARACTERISTICS
in
Fig. 2.
RATINGS
5� 6, 8, 10, 12
4,
Company.
IEEE
NBMA
and standards;
12
Should
3