Test 28 - Check Fuses F1 And F2; Test 29 - Check Fuse F3; Test 30 - Check Main Circuit Breaker - Generac Power Systems 7 kW NG Repair Manual

Section 3.4
Diagnostic Tests
CONTACTOR changes position, the limit switches contacts
change state to become OPEN.
Procedure
With the AUTO-OFF-MANUAL switch in the OFF position, the
generator main circuit breaker "Open", and Utility Voltage
disconnected from the transfer switch, test limit switches SW2
and SW3 as follows.
1. To prevent interaction, disconnect Wire 126 and Wire A
from the limit switch (SW2) terminals.
2. Set the Volt-Ohm-Milliammeter (VOM) to measure
resistance.
3. Connect the VOM meter test leads across the two
outer terminals on SW2 from which the wires were
disconnected.
4. Manually actuate the CONTACTOR to the "Standby"
position, measure and record the resistance.
5. Manually actuate the CONTACTOR to the "Utility" position,
measure and record the resistance.
6. Repeat Step 4 and 5 several times and verify the VOM
reading at each switch position.
7. To prevent interaction, disconnect Wire 205 and Wire B
from the limit switch (SW3) terminals.
8. Connect the VOM meter test leads across the two
outer terminals on SW3 from which the wires were
disconnected.
9. Manually actuate the CONTACTOR to the "Standby"
position, measure and record the resistance.
10. Manually actuate the CONTACTOR to the "Utility" position,
measure and record the resistance.
11. Repeat Step 4 and 5 several times and verify the VOM
reading at each switch position.
Coil Nominal Resistance is 480-520k ohms
Results
1. If the VOM indicated CONTINUITY in Step 4 and 10 and
INFINITY in Step 5 and 9 the limit switches are good, refer
back to flowchart
2. If the VOM did NOT indicate CONTINUITY in Step 4 or 10
and INFINITY in Step 5 or 9 the limit switch(es) are bad,
repair or replace appropriate switch(es).
TEST 28 – CHECK FUSES F1 AND F2
Discussion
Fuses F1 and F2 are connected in series with the N1 and N2
circuits, respectively. A blown fuse will open the applicable
circuit and will result in (a) generator startup and transfer to the
"Standby", or (b) failure to re-transfer back to utility source.
Page 84
PART 3
Procedure
1. On the generator panel, set the AUTO-OFF-MANUAL
switch to the OFF position.
2. Disconnect Utility from the transfer switch.
3. Remove fuse F1 and F2 from the fuse holder. (see Figure 82).
4. Inspect and test fuses for an OPEN condition with a Volt-
Ohm-Milliammeter (VOM) set to measure resistance,
CONTINUITY should be measured across the fuse.
Results
1. Replace blown fuse(s) as needed.
TEST 29 – CHECK FUSE F3
Discussion
Connected in series with Load Wire T1, F3 provides 120 VAC to
the generator to operate the battery charger. A blown fuse will
result in a possible dead battery situation.
Procedure
1. On the generator panel, set the AUTO-OFF-MANUAL
switch to the OFF position.
2. Disconnect Utility from the transfer switch.
3. Remove fuse F3 from the fuse holder.
4. Inspect and test fuses for an OPEN condition with a Volt-
Ohm-Milliammeter (VOM) set to measure resistance,
CONTINUITY should be measured across the fuse.
Results
1. Replace blown fuse as needed.
TEST 30 – CHECK MAIN CIRCUIT BREAKER
Discussion
Often the most obvious cause of a problem is over-looked. If
the Generator main line circuit breaker (MLCB) is set to "Open",
the electrical loads will not receive power. If the connected
loads are not receiving voltage a possible cause could be, the
MLCB has failed OPEN.
Procedure
The Generator Main Line Circuit Breaker (MLCB) is located
underneath the control panel side cover. If loads are not
receiving power, make sure the breaker is set to the "Closed"
position. If you suspect the beaker has failed, test it as
follows.
1. Set the Volt-Ohm-Milliammeter (VOM) to measure
resistance.
2. With the Generator shutdown, disconnect all wires from
the MLCB terminals, to prevent interaction.
TRANSFER SWITCH