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5. Remove Wire N2A from the utility coil C1.
6. Turn on utility power supply to the transfer switch.
a. If transfer to utility occurs, Wire 23 is grounded.
Proceed to Test 31.
b. If transfer to utility does not occur, proceed to
Step 7.
7. Measure across points A and B. 240 VAC should be
measured.
a. If 240 VAC is not measured, verify utility source.
b. If 240 VAC is measured, proceed to Step 8.
8. Measure across points C (Wire N2A previously removed)
and B. 240 VAC should be measured.
a. If 240 VAC is not measured, repair or replace
Wire N2A.
b. If 240 VAC is measured, proceed to Step 9.
9. Measure across points A and D. 240 VAC should be
measured.
a. If 240 VAC is not measured, repair or replace
Wire N1A.
b. If 240 VAC is measured, proceed to Step 10.
10. Measure across points A and E. 240 VAC should be
measured.
a. If 240 VAC is not measured, repair or replace
Wire N1A.
b. If 240 VAC is measured, proceed to Step 11.
11. Measure across points A and F. 240 VAC should be
measured.
a. If 240 VAC is not measured, replace transfer
relay.
b. If 240 VAC is measured, proceed to Step 12.
12. Measure across points A and G. 240 VAC should be
measured.
a. If 240 VAC is not measured, repair or replace
Wire 126.
b. If 240 VAC is measured, proceed to Step 13.
13. Measure across points A and H. 240 VAC should be
measured.
a. If 240 VAC is not measured, verify limit switch
SW2 is wired correctly. Proceed to Test 33.
b. If 240 VAC is measured, proceed to Step 14.
14. Measure across points A and I. 240 VAC should be
measured.
a. If 240 VAC is not measured, repair or replace
Wire A.
b. If 240 VAC is measured, replace utility coil C1.
Coil nominal resistance is 1-2 megohms.
TEST 33 – TEST LIMIT SWITCH SW2 AND SW3
DISCUSSION:
The limit switches are wired to the normally closed
contacts. When the switches are activated the
contacts open.
PROCEDURE:
With the generator shut down, the generator main
circuit breaker turned OFF, and with the utility power
supply to the transfer switch turned OFF, test limit
switch SW2/SW3 as follows:
1. To prevent interaction, disconnect Wire 126 and Wire A
from limit switch SW2 terminals.
2. Set a VOM to its “R x 1” scale and zero the meter.
3. See Figure 1. Connect the VOM meter test leads
across the two outer terminals from which the wires
were disconnected.
4. Manually actuate the main contacts to their Standby
position. The meter should read CONTINUITY.
5. Manually actuate the main contacts to their Utility
position. The meter should read INFINITY.
6. Repeat Steps 4 and 5 several times and verify the VOM
reading at each switch position.
7. To prevent interaction, disconnect Wire 205 and Wire B
from limit switch SW3 terminals.
8. See Figure 1. Connect the VOM meter test leads
across the two outer terminals from which the wires
were disconnected.
9. Manually actuate the main contacts to their Standby
position. The meter should read INFINITY.
10. Manually actuate the main contacts to their Utility
position. The meter should read CONTINUITY.
11. Repeat Steps 4 and 5 several times and verify the VOM
reading at each switch position.
RESULTS:
1. If Limit Switch SW2 or SW3 fails the test, remove and
replace the switch or adjust switch until it is actuated
properly.
TEST 34 – CHECK FUSES F1 AND F2
DISCUSSION:
Fuses F1 and F2 are connected in series with the N1
and N2 circuits, respectively. A blown fuse will open
the applicable circuit and will result in (a) generator
startup and transfer to “Standby”, or (b) failure to
retransfer back to the utility source.
Page 82
PART 3
TRANSFER SWITCH
SECTION 3.4
DIAGNOSTIC TESTS