Guardian 4721, Repair Manual

Page: 101 / 115

OPERATIONAL TESTS
AND ADJUSTMENTS
SECTION 5.1
SYSTEM FUNCTIONAL TESTS
PART 5
Page 97
SYSTEM VOLTAGE TESTS
1. Turn ON the “Utility” power supply to the transfer switch
using whatever means provided (such as a “Utility” main
line circuit breaker).
DANGER: PROCEED WITH CAUTION. THE
TRANSFER SWITCH IS ELECTRICALLY HOT.
CONTACT WITH LIVE TERMINALS OR WIRES
WILL CAUSE HAZARDOUS AND POSSIBLY
DEADLY ELECTRICAL SHOCK.
2. Use an accurate AC voltmeter to check line-to-line volt-
age. On 2-pole switches, check across terminals N1 and
N2. The voltage must be correct and compatible with
rated transfer switch voltage, as listed on the transfer
switch DATA PLATE.
3. When certain that “Utility” source voltage is correct and
compatible, set the generator’s AUTO-OFF-MANUAL
switch to OFF.
4. Turn OFF the “Utility” power supply to the transfer switch.
5. Check that the generator’s main line circuit breaker is set
to ON or “Closed”.
6. On the generator panel, set the AUTO-OFF-MANUAL
switch to MANUAL. The engine should crank and start.
7. Let the generator engine stabilize and warm up for a few
minutes.
DANGER: PROCEED WITH CAUTION. THE
TRANSFER SWITCH IS ELECTRICALLY HOT.
CONTACT WITH LIVE TERMINALS OR WIRES
WILL CAUSE DANGEROUS AND POSSIBLY
DEADLY ELECTRICAL SHOCK.
8. Use an accurate AC voltmeter to check line-to-line volt-
age across Terminal Lugs E1 and E2. Rated generator
voltage should be indicated and must be compatible with
the transfer switch rated voltage.
9. Use an accurate AC frequency meter to check for proper
frequency. Connect the frequency meter test leads
across Terminal E1 and the “Neutral” block. Frequency at
no-load should be about 60 Hertz.
10.After all voltage and frequency measurements have
been completed, set the generator’s main circuit breaker
to its OFF or “Open” position.
NOTE: Do NOT proceed until generator AC output
voltage and frequency are correct. If no-load volt-
age and frequency are both correspondingly high
or low, the engine governor may require adjust-
ment. If AC frequency is good, but AC voltage is
high or low, the AC voltage regulator may require
adjustment.
GENERATOR TESTS UNDER LOAD
1. Set the generator’s main line circuit breaker to OFF or
“Open”.
2. Set the AUTO-OFF-MANUAL switch to OFF.
3. Turn OFF the “Utility” power supply to the transfer switch
using whatever means provided (such as a “Utility” main
line circuit breaker).
4. Manually actuate the transfer switch main contacts to
their STANDBY position, i.e., “Load” connected to the
“Standby” source.
5. Set the AUTO-OFF-MANUAL switch to MANUAL. The
engine should crank and start. When it starts, let it stabi-
lize and warm up for a few minutes.
6. Actuate the generator’s main circuit breaker to its ON or
“Closed” position.
7. Turn ON electrical loads equal to the full rated
wattage/amperage capacity of the generator. DO NOT
OVERLOAD THE UNIT.
8. With maximum rated load applied, check AC voltage and
frequency across Transfer Switch Terminals E1/E2 (1-
phase). Voltage should be greater than 230 volts AC.
Frequency should be greater than 58 Hz.
9. Let the generator run at its maximum rated load for 30
minutes. Listen for unusual noises, evidence of vibration,
overheating, oil and coolant leaks, etc.
10.When checkout under load is completed, set the genera-
tor’s main line circuit breaker to OFF or “Open”.
11.Let the generator run at no-load for a few minutes. Then,
set the AUTO-OFF-MANUAL switch to OFF to stop the
engine.
12.Make sure all power supplies to the transfer switch are
turned OFF. Then, actuate the transfer switch back to its
UTILITY position (“Load” connected to “Utility, power
source).
13.Turn ON the “Utility” power supply to the transfer switch.
14.Set the AUTO-OFF-MANUAL switch to AUTO. The sys-
tem is now set for fully automatic operation.
TESTING AUTOMATIC OPERATION
1. Set the generator’s AUTO-OFF-MANUAL switch to OFF.
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