Kohler APM402, Operation

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1.3.2 Voltage Regulator and Calibration Specifications
The controller has a voltage regulation function that is internal to the processor. This means that no external voltage regulator
is necessary. The voltage regulation of the controller uses root mean square (rms) sensing for fast response to changes in
indicated and regulated voltages resulting in excellent regulation accuracy.
1.3.3 Voltage Regulator Adjustments
The descriptions of the voltage regulator adjustments and features follow. Refer to the Factory-Defined Settings List shown in
the section titled: Status Event and Fault Specifications for voltage regulator adjustments. See Appendix titled: Voltage Regulator
Definitions and Adjustments, for additional information and to customize adjustments for specific applications.
Voltage Adjustment. The voltage adjustment allows the user to enter the desired generator set output level. This regulated
level setting is the average of the three line-to-line voltages in three-phase configurations or L1-to-L2 in single phase
configurations.
Submenus display the individual line-to-line voltages. These voltages are for reference only and are relevant in unbalanced load
conditions. The voltage adjust setpoint can be changed to accommodate an important phase in an unbalanced system.
Underfrequency Unload Frequency Setpoint. This adjustment affects the voltage droop (volts per Hz) when load is applied
and underfrequency occurs. The underfrequency unload setting defines the setpoint where underfrequency starts. Any frequency
below the setpoint causes the voltage to drop thus reducing the load allowing the engine speed to recover according to the
underfrequency unload slope setting.
Engine speed recovery depends upon characteristics such as engine make, fuel type, load types, and operating conditions. The
underfrequency unload setting should match the engine speed recovery characteristics for the application.
Underfrequency Unload Slope. This setting determines how much the voltage drops during an underfrequency condition.
Typically, applying a large electrical load causes a dip in engine speed and frequency. The voltage regulator reduces voltage,
allowing engine speed recovery. The volts-per-Hz setting determines the amount of voltage drop.
Regulator Gain. Regulator gain refers to the gain of the control system. Generally, the higher the gain the faster the system
responds to changes and the lower the gain, the more stable the system.
If the voltage is slow to recover when loads are applied or removed, increase the regulator gain. If the voltage is unstable,
decrease the regulator gain.