Guardian Technologies 4758 - Manual (Page 36)

SECTION 2.4
DIAGNOSTIC TESTS
AC GENERATORS
INTRODUCTION
This section is provided to familiarize the service
technician with acceptable procedures for the testing
and evaluation of various problems that could be
encountered on prepackaged standby generators with
air-cooled engine. Use this section of the manual in
conjunction with Section 2.3, "Troubleshooting Flow
Charts". The numbered tests in this section
correspond with those of Section 2.3.
Test procedures in this section do not require the use
of specialized test equipment, meters or tools. Most
tests can be performed with an inexpensive volt-ohm-
milliammeter (VOM). An AC frequency meter is
required, where frequency readings must be taken. A
clamp-on ammeter may be used to measure AC
loads on the generator.
Testing and troubleshooting methods covered in this
section are not exhaustive. We have not attempted to
discuss, evaluate and advise the home standby
service trade of all conceivable ways in which service
and trouble diagnosis might be performed. We have
not undertaken any such broad evaluation.
Accordingly, anyone who uses a test method not
recommended herein must first satisfy himself that
the procedure or method he has selected will
jeopardize neither his nor the product’s safety.
SAFETY
Service personnel who work on this equipment must
be made aware of the dangers of such equipment.
Extremely high and dangerous voltages are present
that can kill or cause serious injury. Gaseous fuels
are highly explosive and can be ignited by the
slightest spark. Engine exhaust gases contain deadly
carbon monoxide gas that can cause
unconsciousness or even death. Contact with moving
parts can cause serious injury. The list of hazards is
seemingly endless.
When working on this equipment, use common sense
and remain alert at all times. Never work on this
equipment while you are physically or mentally
fatigued. If you don’t understand a component, device
or system, do not work on it.
TEST 1- CHECK MAIN CIRCUIT BREAKER
DISCUSSION:
Often the most obvious cause of a problem is
overlooked. If the generator main line circuit breaker
is set to OFF or "Open", no electrical power will be
supplied to electrical loads. If loads are not receiving
power, perhaps the main circuit breaker is open or
has failed.
PROCEDURE:
The generator main circuit breaker is located on the
control panel. If loads are not receiving power, make
sure the breaker is set to "On" or "Closed".
If you suspect the breaker may have failed, it can be
tested as follows (see Figure 1):
1. Set a volt-ohm-milliammeter (VOM) to its "R x 1" scale
and zero the meter.
2. With the generator shut down, disconnect all wires from
the main circuit breaker terminals, to prevent interaction.
3. With the generator shut down, connect one VOM test
probe to the Wire 11 terminal of the breaker and the
other test probe to the Wire E1 terminal.
4. Set the breaker to its "On" or "Closed" position. The
VOM should read CONTINUITY.
5. Set the breaker to its OFF or "Open" position and the
VOM should indicate INFINITY.
6. Repeat Steps 4 and 5 with the VOM test probes
connected across the breaker's Wire 44 terminal and
the E2 terminal.
RESULTS:
1. If the circuit breaker tests good, go on to Test 2.
2. If the breaker tests bad, it should be replaced.
Figure 1. Generator Main Circuit Breaker Test Points
PART 2
Page 2.4-1