EGCP-2 Engine Generator Control Package Manual 26086
102 Woodward
Voltage Bias Output
The Voltage Bias Offset in the Calibration menu is used to impose an offset
voltage on the voltage bias output to the automatic voltage regulator. This DC
voltage offset is applied to the voltage bias input of the automatic voltage
regulator, and is maintained as a starting point for all voltage bias operations
used by the EGCP-2.
Most regulators which have a voltage trim bias input require a 0.0 Vdc voltage
bias offset. These types of regulators operate with a ±DC voltage applied to this
trim input. The voltage is then centered around zero volts offset, or zero Voltage
Bias.
110% Rated Generator Voltage
90% Rated Generator Voltage
Relationship Between Voltage Bias and Generator Voltage
(Voltage Regulators which take a +/0/- voltage bias input)
0% Voltage Bias Offset (0.0 VDC)
-100% Bias
+100% Bias
Rated Generator Voltage
Figure 5-1. Relationship Between Voltage Bias and Generator Voltage
Some regulators cannot accept a ± voltage trim input, and require a voltage bias
signal that is only positive (or negative) in value. In cases such as these the
Voltage Bias offset can be used to raise the offset of the voltage bias output to a
level which allows more positive and less positive voltage adjustment around a
positive offset voltage.
Voltage Bias Offset will affect the rated voltage of the generator at synchronous
speed prior to the generator breaker closing. The effect the voltage bias offset
has on the generator voltage can be observed by running the unit in a test mode,
and measuring the generator voltage. It is recommended that the voltage
adjustment of the automatic voltage regulator be set for the desired rated voltage
of the generator with the EGCP-2 Voltage Bias Offset applied to the regulator.
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