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Momentarily (one second or so) apply 125 Vdc to the
terminals shown in the chart. Starting with both
shunts all the way in, turn out the right-hand shunt
screw until the relay closes its right-hand trip contact
at 14 volts dc.
NOTE: In the calibration of a PM-23, the alarm unit (2)
contact must be blocked open so as not to
affect the tripping unit pickup. (This will give
approximately 2 mA through the relay coil.)
Now draw out the left-hand shunt until the relay
resets with toggle action (not gradually) at not
less than 10 volts dc. When the calibration is
approximately correct, again apply 125 volts dc
to the indicated terminals, then recheck the
pickup and dropout voltage, making any neces-
sary trimming adjustments of the shunts. When
the relay is properly adjusted, the application
of 125 volts dc will not change the pickup or
dropout voltage points. The relay should trip
and reset with toggle action in this application.
This will require both shunt screws to be with-
drawn farther than for floating action.
9.1.9.
Ground Alarm Unit (5)
For the PM-5 relay, turn both shunt screws all the
way in, then back them out five turns each. Pass a
current of 0.3 mA dc in terminal 6 and out terminal 7.
Following the same general procedure as described
previously in the section entitled "Alarm Unit (1),"
adjust the shunt screws so that the left-hand contact
closes at 0.3 mA. Now pass 0.3 mA dc in terminal 9
and out terminal 8, and adjust for closing of the right-
hand contact at 0.3 mA. Recheck both pickup points
several times, and make trimming adjustments of
both shunts as required to obtain contact closing at
0.3 mA dc in each direction.
For the ground unit (5) of the PMA, PMD, and PMG-
13 relays, connect a variable resistance of about
50,000 ohms in series with a 0-1 dc milliammeter
between the terminals indicated in the following
table:
Turn the shunts all the way in, then back them out
five turns each. With the relay connected as shown in
Courtesy of NationalSwitchgear.com
Relay Terminals
Relay
L.H. Contact Check
†
PMA
3
and 6
PMD
†
5
and 6
PMG-13
†
3
and 8
†
Milliammeter positive to this terminal
the left-hand column of the table, apply rated voltage
to the relay and adjust the 50,000 ohm resistor for 0.3
mA dc. Now following the procedure in the previous
paragraph for the PM-5 relay, adjust the shunts until
the left-hand contact closes at 0.3 mA dc. Change
the connections as indicated in the right-hand col-
umn, and adjust the opposite shunt until the right-
hand contact closes. Recheck back and forth several
times and make necessary trimming adjustments to
obtain pickup at 0.3 mA in each direction. The arma-
ture will move gradually as the current is changed for
this relay unit.
9.1.10. ICS Unit
Close the main relay tripping contact circuit with a
jumper connected directly across the contact termi-
nals of the polar unit. Pass sufficient direct current
through the relay trip circuit to close the contacts of
the ICS unit. This value of current should not be
greater than the ICS tap setting being used (0.2 or
2.0). The indicator target should drop freely. The con-
tact gap should be approximately 0.047 inch between
the bridging moving contact and the adjustable sta-
tionary contacts. The bridging moving contact should
touch both stationary contacts simultaneously.
10. RENEWAL PARTS
Repair work can be done most satisfactorily at the
factory. However, interchangeable parts can be fur-
nished to the customers who are equipped for doing
repair work. When ordering parts, always give the
complete nameplate data.
I.L. 41-973.5Q
R.H. Contact Check
†
3 and 7
†
5 and 7
†
3 and 9
13
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