Adjustment Procedure (12.5 Kw And Older 15 Kw Units); Adjustment Procedure (Newer 15 Kw And All 17.5 Kw Units); Circuit Breakers; Rotor Residual Magnetism - Generac Power Systems GP Series Diagnostic And Repair Manual

Figure 1-5. Voltage Regulator Found on 12.5 kW and
Older Style 15 kW Units (Typical)
Figure 1-6. Voltage Regulator Found on Newer Style
15 kW Units and All 17.5 kW Units (Typical)
Adjustment Procedure (12.5 kW and Older 15
kW Units)
The voltage regulator is equipped with three light emitting
diodes (LED's). These LED's are normally on during
operation when no system faults exist. The red regulator
LED is on when the regulator is on and functioning. The
yellow sensing LED is powered by sensing input to the
regulator from the stator AC power windings. The green
excitation LED is powered by stator excitation winding
output.
The following four adjustment potentiometers are
provided:
• Voltage Adjust
•
Gain
• Stability
• Under Frequency Adjust
Connect an AC voltage/frequency meter across
1.
wires 11 and 44 at the 50A main circuit breaker.
Verify frequency is between 59-61Hz.
On the regulator, set the adjustment pots as
2.
follows:
• Voltage Adjust – turn fully counterclockwise
• Gain – turn to midpoint (12 O'clock)
•
Stability – turn to midpoint (12 O'clock)
• Under Frequency – turn to midpoint (12 O'clock)
Start the generator. This adjustment will be done
3.
under a no-load condition.
Diagnostic Repair Manual
Turn the regulator voltage adjust pot clockwise to
4.
obtain a line to line voltage of 238-242 VAC.
NOTE: If the red regulator LED is flashing, slowly turn
the Stability pot either direction until flashing stops.
Adjustment Procedure (Newer 15 kW and All
17.5 kW Units)
A single red lamp (LED) illuminates during normal
operation. The lamp will become dim if excitation winding
004711
AC output diminishes. It will extinguish on occurrence of
an open condition in the sensing AC output circuit.
An adjustment potentiometer permits the stator AC
power winding voltage to be adjusted. Perform this
adjustment with the generator running at no-load, and
with a 62 Hz AC frequency (62 Hz equals 3720 rpm). At
the stated no-load frequency, adjust to obtain a line-to-
line AC voltage of approximately 252 volts.

Circuit Breakers

Each individual outlet on the generator is protected by a
004712
circuit breaker to prevent overload.

Rotor Residual Magnetism

The generator revolving field (rotor) may be considered
to be a permanent magnet. Some residual magnetism is
always present in the rotor. This residual magnetism is
sufficient to induce a voltage into the stator AC power
windings of approximately 2-12 VAC.

Field Boost Circuit

When the engine is cranked during start-up, the start stop
relay (SSR) will be energized. The normally open contacts
of the SSR will close and wire 15 will supply 12 VDC to
wire 14. Connected to wire 14 is a resistor (R1) and a
diode (D1). The resistor will limit current flow, and the
diode will block voltage regulator DC output. Once
through the resistor and diode it becomes wire 4, and wire
4 then connects to the positive brush. The effect is to flash
the field every time the engine is cranked. Field boost
current ensures sufficient pickup voltage is available on
every startup to turn the voltage regulator on and build AC
output voltage.
While the SSR remains energized, field boost current is
always available during cranking and running. Diode D1
prevents or blocks the higher voltage regulator DC output
from reaching the wire 14 run circuit.
Field boost voltage is reduced from battery voltage by
resistor R1.
approximately 9 to 10 VDC.
Section 1 Description and Components
A digital multimeter will indicate
3