Test 26 - Utility Control Circuit; Test 27 - Test Limit Switches - Generac Power Systems 7 kW NG Repair Manual

TRANSFER SWITCH
TERMINAL STRIP
CUSTOMER SIDE
N1
N2 T1
209 210 0 194 23
209 210 0 194 23
TERMINAL BLOCK
Figure 79. Transfer Relay Test Points
15. Continue to have Wire 23 disconnected on the customer
side.
16. Disconnect the J4 connector from the controller.
17. Set VOM to measure resistance.
18. Connect one meter test lead to Wire 23 connected at the
terminal strip (see Figure 79) and connect the other meter
test lead to a clean frame ground.
a. If INFINITY or OPEN was measured, replace the
controller.
b. If CONTINUITY was measured, Wire 23 is shorted to
ground. Repair or replace Wire 23 between the J4
connector and the Generator terminal strip.
TEST 26 – UTILITY CONTROL CIRCUIT
Discussion
Refer to Figure 78. The utility coil (C1) requires 240 VAC to
energize. When the transfer relay (TR1) de-energizes, 240 VAC
is applied to the C1 coil. Once energized, the coil will pull the
CONTACTOR up to the "Utility" position. Once in the "Utility"
position, the limit switch (SW2) will open, removing AC voltage
from the C1 coil.
Procedure
Refer to Figure 78.
1. Set the AUTO-OFF-MANUAL switch to the OFF position.
Disconnect Wire 194 from the transfer switch terminal
strip.
2. Set Volt-Ohm-Milliammeter (VOM) to measure AC voltage.
3. Disconnect Utility supply voltage from the transfer switch.
4. Verify the transfer switch is in the "Standby" position.
5. Turn on Utility supply voltage to the transfer switch.
PART 3
a. If transfer to Utility occurs, the transfer relay (TR1) was
energized preventing a re-transfer to Utility. Proceed to
Test 25 "Check Wire 23 Circuit".
b. If transfer to Utility does NOT occur, proceed to Step 7.
6. Remove Wire N2A from the utility coil (C1).
7. Measure across points A and B, the VOM should indicate
240 VAC.
a. If 240 VAC is NOT measured, verify Utility source is ON.
b. If 240 VAC was measured, proceed to Step 8.
8. Measure across point C (Wire N2A previously remove)
and B, the VOM should indicate 240 VAC.
a. If 240 VAC was NOT measured, repair or replace Wire
N2A.
b. If 240 VAC was measured, proceed to Step 9.
9. Measure across points A and D, the VOM should indicate
240 VAC.
a. If 240 VAC was NOT measured, repair or replace Wire
N1A.
b. If 240 VAC was measured, proceed to Step 10.
10. Measure across points A and E, the VOM should indicate
240 VAC.
a. If 240 VAC was NOT measured, repair or replace Wire
N1A.
b. If 240 VAC was measured, proceed to Step 11.
11. Measure across points A and F, the VOM should indicate
240 VAC.
a. If 240 VAC was NOT measured, replace transfer relay.
b. If 240 VAC was measured, proceed to Step 12.
12. Measure across points A and G, the VOM should indicate
240 VAC.
a. If 240 VAC was NOT measured, repair or replace Wire
126.
b. If 240 VAC was measured, proceed to Step 13.
13. Measure across points A and H, the VOM should indicate
240 VAC.
a. If 240 VAC was not measured, verify the limit switch
(SW2) is wired correctly and proceed to Test 27 "Test
Limit Switches"
b. If 240 VAC was measured, proceed to Step 14.
14. Measure across points A and I, the VOM should indicate
240 VAC.
a. If 240 VAC was not measured, repair or replace Wire A.
b. If 240 VAC was measured, replace the C1 coil.
TEST 27 – TEST LIMIT SWITCHES
Discussion
Wired to the normally CLOSED contacts, the limit switches
provide a means to interrupt the transfer circuits. When the
Section 3.4
Diagnostic Tests
Page 83