Test 23 - Test Transfer Relay; Test 24 - Test Standby Control Circuit - Generac Power Systems 7 kW NG Repair Manual

TRANSFER SWITCH
a. If voltage is present, repair Wire 194 between the
Generator terminal strip and transfer switch terminal
strip.
b. If voltage is not present, proceed to Step 20.
23. Locate and disconnect the J4 connector from the
controller.
24. Set VOM to measure resistance.
25. Connect one meter test lead to Wire 194 at the Generators
customer connection terminal strip. Connect the other
meter test lead to J4 Pin 19 (Wire 194) at the connector.
26. Continuity should be measured.
a. If continuity is not measured, repair pin connection and/
or Wire 194 between the connector and terminal strip.
b. If continuity is measured, proceed to Step 24.
27. Remove the Generator fuse.
28. Reconnect J4 connector.
29. Re-install the fuse.
30. Disconnect Wire 194 from the Generators terminal strip.
31. Set VOM to measure DC voltage.
32. Connect one meter test lead to Wire 194. Connect the
other meter test lead to a clean frame ground, 12 VDC
should be measured.
a. If 12 VDC is not measured, replace the controller.
b. If 12 VDC is measured, a short exists on Wire 194 or
the TR1 relay. Repair or replace as needed
TEST 23 – TEST TRANSFER RELAY
Discussion
In automatic mode, transfer to Standby will not occur until the
transfer relay (TR1) energizes. When TR1 relay energizes,
Generator voltage is available to operate the standby closing
coil. Without Generator source voltage available, the closing
coil will remain de-energized and transfer to the "Standby"
position will not occur. This test will determine if the TR1 relay
is functioning normally.
N1A
15B
COIL NOMINAL RESISTANCE = 120 Ohms
Figure 75. Transfer Relay Test Points
PART 3
126 205
E1
23
Procedure
1. Disconnect all wires from the TR1 relay to prevent
interaction. See Figure 75.
2. Using jumper wires, connect one jumper wire from
the positive post of the battery to relay Terminal A and
connect the other jumper wire from the negative post of
the battery to relay Terminal B.
3. Set the Volt-Ohm-Milliammeter (VOM) to measure
resistance.
4. With the relay de-energized, connect the VOM test leads
across relay Terminals "A" and "B", measure and record
the resistance
5. Connect the VOM test leads across relay Terminals 6 and
9, measure and record the resistance.
a. Energize the relay, the meter should indicate INFINITY.
b. De-energize the relay ,the VOM should indicate
CONTINUITY
6. Repeat Step 5 across relay Terminals 7 and 1.
Table 16.
CONNECT VOM TEST
LEADS ACROSS
Terminals 6 and 9
Terminals 1 and 7
Terminal A and B
Results
1. Compare the results with Table 16. If the relay tests good,
refer back to flow chart.
2. Replace relay if found defective.
TEST 24 – TEST STANDBY CONTROL CIRCUIT
Discussion
Refer to Figure 76. The standby coil (C2) requires 240 VAC
to energize. When the transfer relay energizes, 240 VAC is
applied to the C2 coil. Once energized, the coil will pull the
CONTACTOR down to the "Standby" position. Once in the
"Standby" position, the limit switch (SW3) will open, removing
AC voltage from the C2 coil.
Procedure/Results
1. Set the Volt-Ohm-Milliammeter (VOM) to measure AC
voltage.
2. Verify the CONTACTOR is in the "Utility" position.
3. Remove Wire E2 from the C2 coil.
4. Set the AUTO-OFF-MANUAL switch to AUTO. Turn off
Utility power supply to the transfer switch, simulating a
utility failure. The Generator should start and the transfer
relay should energize.
Section 3.4
Diagnostic Tests
DESIRED METER READING
ENERGIZED DE-ENERGIZED
Continuity Infinity
Infinity Continuity
120 Ohms
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