Guardian 4721, Repair Manual

Page: 102 / 115

2. Turn OFF both the “Utility” and “Standby” power supplies
to the transfer switch.
3. If necessary, manually actuate the transfer switch main
contacts to their UTILITY position, i.e., “Load” connected
to the “Utility” source.
4. Turn ON the “Utility” power supply to the transfer switch.
5. Set the generator’s main line circuit breaker to its ON or
“Closed” position.
6. Set the generator’s AUTO-OFF-MANUAL switch to its
AUTO position.
7. Turn OFF the “Utility” power supply to the transfer switch.
a. The generator engine should crank and start.
b. After the control board’s “engine warm-up timer”
has timed out, transfer of “Load” circuits to the
“Standby” power supply should occur.
8. Wait about 10-15 minutes, then turn ON the “Utility”
power supply to the transfer switch.
a. After about six (6) seconds, retransfer back to
the “Utility” source should occur.
b. After an “engine cool down timer” (one minute)
has timed out and after any time remaining on
an “engine minimum run timer” has elapsed, the
engine should shut down.
NOTE. The “engine minimum run timer” comes on
during startup in automatic mode. Engine must
run for about 13 minutes before it can be shut
down automatically. The timer prevents shutdown
of a cold engine. Engine can be shut down manu-
ally at any time.
PART 5
Page 98
OPERATIONAL TESTS
AND ADJUSTMENTS
SECTION 5.1
SYSTEM FUNCTIONAL TESTS