GE IAV51A Instructions Manual page 3

General
These relays are of the induction disk construction.
The disk is actuated by a potential operating coil on
U
a laminated -magnet. The disk shaft carries the
moving contact, which completes the trip or alarm
circuit when it touches the stationary contact or
contacts. The disk shaft is restrained by a spiral
spring to give the proper contact closing voltage,
and its motion is retarded by permanent magnets
acting on the disk to give the correct time delay.
There is a seal-in element mounted to the left of
the shaft as shown in Fig.
in series and its contacts in parallel with the main
contacts such that when the main contacts close, the
seal-in element picks up and seals in. When the seal­
in element 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 relays are all mounted in dcawout �ses. The
drawout case has studs for external connections at
the bottom end. The electric connections between
the relay unit and the case are made through station­
ary molded inner and outer blocks; between the
blocks nests a removable connecting plug which
completes the circuits. The outer block, attached to
the case, has the studs for external connections,
and the inner block has terminals for the internal
connections.
The relays may be surface or semiflush mounted.
Surface mounted relays have studs extending from
the back of the case and are mounted on the panel
surface. Semiflush mounted relays have a flange
around the front of the case and are mounted in panel
openings, the flange being attached to the panel
surface.
The cover page shows a typical drawout-case
relay. The component parts such as the cradle, case,
connecting plug, and cover, are shown in Fig.
The relay mechanism is mounted in the steel
framework, called the cradle, and is a complete unit
with all leads being terminated at the inner block.
This cradle is held fi r mly in the case by a latch at
both top and bottom and by a guide pin at the back
of the case. The connecting plug, besides making the
electric connections between the respective blocks
of the cradle and case, also locks the lower latch in
place. The cover, which is drawn to the cradle by
thumbscrews, holds the connecting plug in place.
To draw out the cradle, the cover must first be
removed. Then the connecting plug can be drawn
out. In so doing, the trip circuit is first opened, then
the voltage circuits are opened. After the connecting
plug has been removed, the lower latch can be re­
leased and the cradle easily drawn out. To replace
the cradle, the reverse order should be followed.
VOLTAGE RELAYS
TYPE IAV
1.
This element has its coil
1.
Note: Care must be taken to insert the connecting
plug slowly on relays that have contacts which are
closed when de-energized but open under
operating conditions. Put the plug in until its con­
tacts just touch those of the terminal blocks, which
can easily be felt. After relay contacts open, push
plug in all the way.
Application
These relays are protective devices to close trip
or alarm circuits whenever the voltage applied to
their operating coils reaches some predetermined
value. The functions are described in greater detail
in the following paragraphs.
Operating Characteristics
The IA VS lA relay has single-circuit closing con­
tacts which close as the voltage 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 at the top of the shaft. The time-voltage
characteristics of the IA VSlA relay are shown in
Fig. 2.
The IAV52A relay is similar to the IAVSlA relay
except that it has additional contacts for closing a
second circuit.
The IA V53A relay has double-throw contacts. The
left-hand contacts close as the voltage increases to
some predetermined value. The right-hand contacts
close when the voltage decreases to some lower value.
Between these two voltage values both contacts are
open. Time voltage characteristics are shown in
Fig. 3.
The IA V54A relay has single-circuit contacts
which close when the voltage is reduced to some
predetermined
value. Thus, the contacts are closed
when the relay has no voltage applied to its ter­
minals. Time-voltage characteristics are shown in
Fig. 4.
The IA VSSA relay is similar to the IA V54A relay
except that it has additional contacts for closing a
second circuit.
Ratings
The operating circuit ratings available are 115 or
230 volts at 60, 50 or 25 cycles. The operating coil
will stand rated voltage continuously on any tap and
will stand tap voltage continuously on the taps above
rated voltage.
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 seal-in coil as indicated in the follow­
ing table:
·
normal
3