Section 3.4 - Diagnostic Tests; Introduction; Safety; Transfer Switch Troubleshooting - Generac Power Systems CorePower Repair Manual

TRANSFER SWITCH

INTRODUCTION

This section familiarizes the service technician with acceptable
procedure for the testing and evaluation of various problems
that can occur on pre-packaged transfer switches. Use this
section in conjunction with Section 3.3, "Troubleshooting Flow
Charts." The numbered tests in this section correspond with
those of Section 3.3.
Some test procedures in this section may require the use of
specialized test equipment, meters or tools. Most tests can be
performed with an inexpensive volt-ohm-meter (VOM). An AC
frequency meter is required, where frequency readings must be
taken. To measure AC loads it is acceptable to use a clamp-on
ammeter.
Testing and troubleshooting methods covered in this section
are not exhaustive. No attempt has been made to discuss,
evaluate and advise the home standby service trade of all
conceivable ways in which service and trouble diagnosis must
be performed. 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 products safety.

SAFETY

Service personnel who work on this equipment should be
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 ignite 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.
while you are physically or mentally fatigued. If you do not
understand a component, device or system, do not work on it.

TRANSFER SWITCH TROUBLESHOOTING

It is always good practice to continue to ask questions during
the troubleshooting process. When evaluating the problem
asking some of these questions may help identify the problem
quicker.
• What is the transfer switch doing?
• What was the transfer switch supposed to do?
• Does the transfer switch have the same fault consistently,
and when does it occur?
• Who is controlling it?
• Exactly what is occurring?
• When is it happening?
• Why would this happen?
• How would this happen?
• What type of test will either prove or disprove the cause of
the fault?
PART 3
Never work on this equipment
TEST 27 – CHECK GENERATOR VOLTAGE AT
TRANSFER SWITCH
Procedure
1. Set Volt-Ohm-Milliammeter (VOM) to measure AC voltage
2. With the generator running check generator voltage at the
generator's circuit breaker in the transfer switch. Measure
and record the voltage.
Results
1. If the VOM indicated approximately 240 VAC, refer back to
flow chart.
2. If the VOM did not indicate the correct AC voltage,
investigate the cause of the no AC output.
TEST 28 – TEST TRANSFER OPERATOR
Procedure
1. Using a jumper wire connected to a common ground;
connect a ground to the XFER terminal on the operator.
Observe the rotation of the operator.
2. Disconnect ground from XFER terminal and observe the
rotation of the operator.
Results
1. If the operator transferred to "Standby" when XFER was
grounded and re-transferred back to "Utility" when XFER
was ungrounded, the operator is functioning correctly.
2. If the operator failed to transfer to either "Standby" or
"Utility" positions, refer back to flow chart.
TEST 29 – CHECK 15B/194 CIRCUIT
Procedure
1. Set a Volt-Ohm-Milliammeter (VOM) to measure DC
voltage.
2. Connect one meter test lead to BAT + and connect the
other meter test lead to BAT - on the operator. Measure
and record the voltage.
a. If the VOM indicated battery voltage, replace transfer
operator.
b. If the VOM did not indicate battery voltage, proceed to
Step 3.
3. Connect one meter test lead to Wire 15B and the other
meter test lead to Wire 0 located on the customer
connection block. Measure and record the voltage.
a. If the VOM indicated battery voltage, repair or replace
the wiring between the transfer switch and the
generator.
Section 3.4
Diagnostic Tests
Page 43