Guardian 4389 Repair Manual page 26

SECTION 1.7
AUTOMATIC OPERATING PARAMETERS
SEQ. CONDITION
1 Utility source voltage is
available.
2 Utility voltage dropout below
60% of rated voltage occurs.
3 Utility voltage is still below
60% of rated voltage.
4 Utility voltage is still low after
15 seconds.
5 Utility voltage still low and
the engine has started.
6 Engine running and "engine
warmup timer" times out.
AC output voltage above
50% nominal voltage.
7 Engine running and load is
powered by Standby power.
8 Utility source voltage is
restored above 80% of rated
9 Utility voltage still high after 15
seconds.
10 Utility voltage still high.
11 Engine still running, loads are
powered by Utility source.
12
13 Engine is shut down, loads are
powered by "Utility" source.
Return to Sequence 1.
Page 24
AUTOMATIC OPERATING SEQUENCES CHART
ACTION
No action
A 15-second timer on circuit
board turns on.
15-second timer runs for 15
seconds, then stops.
Circuit board action energizes a
crank relay and a run relay.
See NOTE 1.
Circuit board's "engine warmup
timer" runs for 10 seconds.
Circuit board action energizes a
transfer relay in transfer switch
and transfer to "Standby" occurs.
No further action
Circuit board "voltage pickup
sensor" reacts and a "re-transfer
time delay" turns on.
"Return to Utility Timer" times out Return to Utility Timer
Circuit board action opens the
transfer relay circuit to ground.
Transfer relay de-energizes and
retransfer to "Utility" occurs.
Circuit board "engine cooldown
timer" starts running.
After 1 minute, "engine cooldown Engine Cooldown Timer
timer" stops and circuit board's
run relay de-energizes. Engine
shuts down.
No action.
PART 1
GENERAL INFORMATION
SENSOR, TIMER OR OTHER
Voltage Dropout Sensor on circuit
circuit board.
Voltage Dropout Sensor and 15
second timer on circuit board.
Voltage Dropout Sensor and 15
second timer.
Circuit board crank and run
relays.
Engine Warmup Timer (10 seconds)
Circuit board transfer relay circuit
Transfer switch transfer relay.
Circuit board voltage pickup
sensor continues to seek an
acceptable "Utility" voltage.
Voltage Pickup Sensor (80%)
Return to Utility Timer (15 seconds)
Circuit board transfer relay circuit
Transfer switch transfer relay.
Circuit board Engine Cooldown
Timer (1 minute)
Circuit board Run Relay.
Voltage Dropout Sensor on circuit
circuit board.