Guardian 4389 Diagnostic Repair Manual page 124

OPERATIONAL TESTS
AND ADJUSTMENTS
2. Set the generator AUTO-OFF-MANUAL switch to the
"OFF " position.
3. Turn off all loads connected to the transfer switch
terminals T1 and T2.
4. Turn on the utility power supply to the transfer switch
using the means provided (such as a utility main line
circuit breaker).
DANGER
The transfer switch is now electrically hot.
Contact with hot parts will result in extremely
hazardous and possibly fatal electrical shock.
Proceed with caution.
5. Use an accurate AC voltmeter to check utility power
source voltage across transfer switch terminals N1 and
N2. Nominal line-to-line voltage should be 240 volts AC.
6. Check utility power source voltage across terminals N1
and the transfer switch neutral lug; then across terminal
N2 and neutral. Nominal line-to-neutral voltage should
be 120 volts AC.
7. When certain that utility supply voltage is compatible
with transfer switch and load circuit ratings, turn OFF
the utility power supply to the transfer switch.
8. On the generator panel, set the AUTO-OFF-MANUAL
switch to MANUAL. The engine should crank and start.
9. Let the engine warm up for about five minutes to allow
internal temperatures to stabilize. Then, set the
generator main circuit breaker to its "ON" (or closed)
position.
DANGER
Proceed with caution! Generator power voltage
is now supplied to the transfer switch. Contact
with live transfer switch parts will result in
dangerous and possibly fatal electrical shock.
10.Connect an accurate AC voltmeter and a frequency
meter across transfer switch terminal lugs E1 and E2.
Voltage should be 242-252 volts; frequency should read
about 61-63 Hertz.
11.Connect the AC voltmeter test leads across terminal lug
E1 and neutral; then across E2 and neutral. In both
cases, voltage reading should be 121-126 volts AC.
12.Set the generator main circuit breaker to its OFF (or open)
PART 5
SYSTEM FUNCTIONAL TESTS
position. Let the engine run at no-load for a few minutes to
stabilize internal engine generator temperatures.
13.Set the generator AUTO-OFF-MANUAL switch to OFF.
The engine should shut down.
NOTE: It is important that you do not proceed until
you are certain that generator AC voltage and
frequency are correct and within the stated limits.
Generally, if both AC frequency and voltage are high
or low, the engine governor requires adjustment. If
frequency is correct, but voltage is high or low, the
generator voltage regulator requires adjustment.
GENERATOR TESTS UNDER LOAD
To test the generator set with electrical loads applied,
proceed as follows:
1. Set generator main circuit breaker to its OFF (or open)
position.
2. Turn OFF all loads connected to the Transfer Switch
Terminals T1 and T2.
3. Set the generator AUTO-OFF-MANUAL switch to OFF.
4. Turn off the utility power supply to the transfer switch,
using the means provided (such as a utility main line
circuit breaker).
Do not attempt manual transfer switch
operation until all power voltage supplies to the
transfer switch have been positively turned off.
Failure to turn off all power voltage supplies
will result in extremely hazardous and possibly
fatal electrical shock.
5. Manually set the transfer switch to the STANDBY
position, i.e., load terminals connected to the generator
E1/E2 terminals. The transfer switch operating lever
should be down.
6. Set the generator AUTO-OFF-MANUAL switch to
MANUAL. The engine should crank and start
immediately.
7. Let the engine stabilize and warm up for a few minutes.
8. Set the generator main circuit breaker to its ON (or
closed) position. Loads are now powered by the
standby generator.
9. Turn ON electrical loads connected to transfer switch T1
SECTION 5.1
Page 5.1-2