Voltage Regulator Adjustment; Section 4 - Maintenance; Maintenance Performed By Authorized Service Facilities - Generac Power Systems QuietSource 005031-2 Owner's Manual

Switch Position 8 — Selects whether the control is
in the Normal Mode of operation or Test Mode. In the
Normal Mode of operation, pre-determined governor
gains are used and the gain trimpots on the control
board (Gain, Stability, and Differential) are not active
and have no effect on the gains. In Test Mode the gain
trimpots are active and can be adjusted. See Section
3.4.
3.9 VOLTAGE REGULATOR
ADJUSTMENT
Four adjustment potentiometers are provided on
the voltage regulator installed in the control panel
(Figure 3.4). These are (a) voltage adjust, (b) gain, (c)
stability and (d) underfrequency adjust. The voltage
regulator potentiometers have been factory set and
SHOULD NOT be adjusted. If however, adjustments
are necessary, contact the local Dealer to implement
the following procedure.

High voltage is present inside the control panel
during this procedure.
1. Disconnect all electrical loads from the generator
(initial adjustments are done under no-load con-
ditions).
Figure 3.4 — Voltage Regulator
2. Connect an accurate AC voltmeter and AC fre-
quency meter to the generator's AC output leads.
3. On the voltage regulator, set the potentiometers
as follows:
A. Turn the Voltage Adjust pot fully counterclock-
wise (CCW).
B. Set the GAIN pot to its centered (mid) position.
C. Set the STABILITY pot to its centered (mid)
position.
D. DO NOT adjust the UNDERFREQUENCY
ADJUST pot.
4. Start the engine. Let it stabilize and warm up at
no-load.
Section 4 — Maintenance
Liquid-cooled 25 kW Generators
5. Verify that the three voltage regulator's LED's are
ON.
6. Check the reading on the AC frequency meter.
7. Turn the voltage regulator's VOLTAGE ADJUST
pot to obtain a line-to-line voltage of:
A. 240 VAC if the generator has been configured for
60 Hertz operation.
B. 200 VAC if the generator has been configured for
50 Hertz operation.
8. If the RED REGULATOR LED is flashing, adjust
the STABILITY pot in either direction until the
flashing stops.
9. Apply an electrical load and check the engine
speed recovery.
A. Adjust the UNDERFREQUENCY ADJUST pot
CCW to reduce load during engine recovery.
B. For flat regulation (no voltage decrease as fre-
quency drops) set the UNDERFREQUENCY
ADJUST pot fully CW.
C. To obtain a constant voltage regulation as fre-
quency decreases, set the UNDERFREQUENCY
ADJUST pot fully CCW.
10. With the electrical load still applied, check the
REGULATOR LED for flashing. If the LED is
flashing, adjust the STABILITY pot until the flash-
ing stops.
11. If better response is needed, adjust the GAIN pot
clockwise (CW) as needed. Then (if needed) cor-
rect for stability by adjusting the STABILITY pot.
12. Turn OFF the electrical loads.
13. Verify that all the voltage regulator's LED's are
ON.
14. Turn OFF the generator.
4.1 MAINTENANCE PERFORMED BY
AUTHORIZED SERVICE FACILITIES
EVERY THREE MONTHS
1. Check battery condition.
2. Inspect and test fuel system.
3. Check transfer switch.
4. Inspect exhaust system.
5. Check engine ignition system.
6. Check fan belts.
ONCE EVERY SIX MONTHS
1. Test Engine Safety Devices (low oil pressure, low
coolant level, high coolant temperature).
ONCE ANNUALLY
1. Test engine governor; adjust or repair, if needed.
2. Clean, inspect generator.
3. Flush cooling system.
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