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Voltage Regulators
SMCS Code: 4467
VR6
Personal injury or death can result from high
voltage.
When power generation equipment must be in
operation to make tests and/or adjustments, high
voltage and current are present.
Improper test equipment can fail and present a
high voltage shock hazard to its user.
Make sure the testing equipment is designed for
and correctly operated for high voltage and cur-
rent tests being made.
When servicing or repairing electric power gener-
ation equipment:
• Make sure the unit is off-line (disconnected
from utility and/or other generators power
service) , and either locked out or tagged DO
NOT OPERATE.
• Remove all fuses.
• Make sure the generator engine is stopped.
• Make sure all batteries are disconnected.
• Make sure all capacitors are discharged.
Failure to do so could result in personal injury or
death. Make sure residual voltage in the rotor,
stator and the generator is discharged.
Accidental engine starting can cause injury or
death to personnel working on the equipment.
To avoid accidental engine starting, disconnect
the battery cable from the negative (−) battery ter-
minal. Completely tape all metal surfaces of the
disconnected battery cable end in order to pre-
vent contact with other metal surfaces which
could activate the engine electrical system.
Place a Do Not Operate tag at the Start/Stop
switch location to inform personnel that the
equipment is being worked on.
For generators with Auxiliary Winding Regulation
Excitation Principle (AREP), the voltage regulator is
powered by two auxiliary windings. These windings
are independent from the circuit for detection of
voltage. The first winding is labeled as “X1” and “X2” .
This winding has a voltage that is proportional with
the output voltage of the generator. The second
winding is labeled as “Z1” and “Z2” . This winding has
a voltage that is proportional to the current of the
stator. The voltage from the power supply is rectified
and filtered before being used by the regulator
monitoring transistor. This principle ensures that
regulation is not affected by interference that is
generated by the load.
For generators with PMG excitation, a permanent
magnet generator is added to the generator at the
rear of the generator. The PMG supplies the voltage
regulator with a voltage that is independent of the
main generator winding. The generator has a short
circuit capability of 3 X In for 10 seconds. The
generator also has good immunity to distortion from
the generator load.
The voltage regulator monitors the output voltage
and the voltage regulator corrects the output voltage
of the generator by adjusting the excitation current.
74
SEBU7125-13
Operation Section
Voltage Regulators
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