Guardian 4389 Repair Manual page 123

OPERATIONAL TESTS
AND ADJUSTMENTS
DANGER
THE TRANSFER SWITCH IS NOW ELECTRI-
CALLY "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 genera-
tor 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 ELEC-
TRICAL 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)
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 volt-
age 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.
PART 5
SYSTEM FUNCTIONAL TESTS
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 cir-
cuit 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 posi-
tion, 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 MANU-
AL. 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 stand-
by generator.
9. Turn ON electrical loads connected to transfer switch T1
and T2. Apply an electrical load equal to the full rated
wattage/amperage capacity of the installed generator.
10.Connect an accurate AC voltmeter and a frequency
meter across Terminal Lugs E1 and E2. Voltage should
be greater than 230 volts; frequency should be greater
than 58 Hertz.
11.Let the generator run at full rated load for 20-30 minutes.
Listen for unusual noises, vibration or other indications
of abnormal operation. Check for oil leaks, evidence of
overheating, etc.
12.When testing under load is complete, turn off electrical
loads.
13.Set the generator main circuit breaker to its OFF (or
open) position.
14.Let the engine run at no-load for a few minutes.
SECTION 5.1
Page 121