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Remove jumper from test point TP6 and TP7
on the timer module.
Now when the test switch to terminal 9 is clos
ed, the AR output relay should pickup momentari
ly and reset even though the test switch is left clos
ed. Remember that the BF timer setting should be
16 ms or more longer than the Control Timer.
Reduce voltage to relay terminal 1 8 to 60% of
rated relay voltage. Close test switch and note that
A R relay does not pickup.
Return voltage to normal and reduce voltage to
terminal 9 to 60% of rated relay voltage. Close test
switch and note that A R relay does not pick up.
0
Set voltage to terminal 9 and 1 8 to 80% of
rated relay voltage. Close switch to terminal 1 8
and then 9 . See that A R relay picks up momen
tarily.
Indicating Contactor
Switch ( I C S)
There are two I CS units used. Each may be
checked by placing the ICS tap screw in the
desired tap (0. 2 or 2 Amps). Adj ust the de current
to the tap value.
Test for seal-in by closing switch to terminal 9
and see that each I C S picks u p and seals itself in
the closed position.
The contact gap should be approximately
.047". Both stationary contacts should make with
the moving contacts simultaneously. The in
dicating target should drop just prior to or at the
same time the contacts make.
Routine Maintenance
The relay should be inspected periodically. The
operation of the overcurrent circuits, timers and
indicating contactor switch should be checked
similar to procedure described under SETT INGS.
In addition inspect the X and AR relay contacts. A
contact burnisher S#1 82A836 H 0 1 is recommend
ed for cleaning contacts. The use of abrasive
material for cleaning contacts should be avoided
because of the danger of embedding small particles
in the face of the contact material which might im
pair the contact operation.
Calibration
Use the following procedure for calibrating the
relay if the relay has been taken apart for repairs
or the adj ustments have been disturbed. This
procedure should not be used unless it is apparent
that the relay is not in proper working order.
Overcurrent Detector
Refer to Fig. 7 and 8 or 9 when replacing com
ponents.
If a new module is inserted, it will require
calibration of the dial plate. Other replacement
parts such as a transformer or certain components
on the module such as the reference zener,
operational amplifier, rheostat, etc. m ight require
new scale markings. I n that case a new dial plate
will be necessary.
To mark the dial, first j umper test point TP6
and TP7 on the timer board. Energize the relay
with rated de voltage and apply 0.48 Amps ac
current to phase A. With the tap in the 0.5 position
and the phase multiplier dial knob fully counter
clockwise, rotate the phase A trim pot slowly CCW
(to lower pickup) . Operation of the overcurrent
unit is indicated when the A R output relay picks
up. Verify this adj ustment by increasing the ac
current until the relay again picks up. This should
be between 0.47 and 0.49 amps. N ow turn the front
panel dial knob fully CW. Check to see that
t o
pickup is 1 . 5 5
1 . 80 amps. If it is slightly below
1 .5 5 amps, rotate the phase A trimpot slightly
clockwise to raise the pickup to 1 .5 5 amps. Go
back and check to see that the pickup with the dial
knob fully CCW is no higher than .495 amps. Ad
just knob on shaft so that the high and low operate
point are equidistant from the knob lock. Apply
0 . 5 , 0 . 7 , 0.9, 1 . 1 , 1 .3 , and 1 .5 amps and scribe the
scale at the knob pointer setting at which the out
put relay just operates.
After scribing the scale, set the dial at 0 . 5 amp
(X 1 ) pickup and note what value current the out
put relay operates. Apply current source to phase
C and note at what current value the output relay
operates. If the difference is greater than .025 amp
from phase A, adj ust the phase C trimpot t o bring
the operate point within .025 amps of phase A .
Repeat for phase B i f used.
I. L. 41-776.5A
7
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