GE IAC53A Instructions Manual page 3

TIME OVERCURRENT RELAYS
TYPE lAC
INTRODUCTION
Type
Contact Instan. A-C Trip
Induc. Outline lnt.
Circuits Unit
IAC53A(-)A One No
IAC53B(-~A
One Yes
IAr.53C(- A
One No
JAC53R(-)A
One Yes
IAC54A~-~A
Two No
IAC54B - A
Two Yes
The Types IAC53 and IAC54 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-
Unit Unit &P. D. Conn.
No
One
Fig. 20
Fig. 12
No One
Fig. 20
Fig. 13
Yes On~
Fie:. 20
Fig. 14
Yes
One
Fig. 20 Fig. 15
No One Fig. 20
Fig. 16
No One
'Fig. 20
Fig. 17
.-
mits instantaneous tripping for exteremely high cur-
rents, 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 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 and panel drilling
diagrams.
INDUCTION UNIT
INTRODUCTION APPLICATION
The induction unit is the basic unit in all Type
JAC relays. Figs. 1 and 2 show the induction unit
mounted in the cradle. These units are of the induc-
tion-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.
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.
The induction unit is the main unit in all Type
JAC relays, supplying the very inverse time delay
characteristics of the relay and sounding an 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 anyone 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.
These instructions do not purport to cover all details or variations in equipment nor to provide for
,}very 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 gi ven wi th respect to local codes and ordinances
bec~use
they vary greatly.
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