Hobart 60CU20 Operation And Maintenance Manual With Illustrated Parts List page 35

OM-2226 / Operation and Maintenance Manual
60CU20 / Series 500062 / 400 Hz. Generator Set
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When a load is removed from the alternator, the alternator voltage rises. The rectified three-
phase voltage-sensing signal increases, causing this signal to be higher than the reference
signal. The associated voltage regulator circuitry causes the field power of the rotary exciter
to decrease, lowering the alternator voltage until the voltage returns to regulated value.
The line-drop voltage compensation circuit consists of a current transformer on each phase of the
load circuit, and fixed resistance in parallel with each current transformer. The current
transformers detects the magnitude of current flowing through the power cables from the
alternator to its load and feeds a signal into the voltage regulator PC board. The PC board
processes this signal to change the output voltage proportional to the current draw. The regulator
output increases slightly so that the alternator output voltage is equal to the regulated voltage
plus the voltage drop in the lines. The line-drop compensation potentiometer may be adjusted to
match exactly the voltage drop of the power cables carrying the load current.
The under/over frequency protection, EF signal, and lost neutral detection are also monitored by
the REG and will signal the CTL when a fault has occurred. The CTL issues the appropriate
command that corresponds to the fault.
May 2, 2013
Figure 10: Voltage Regulator PC Board
Chapter 1-1
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