AC GENERATORS
PART 2
Page 41
Voltage Regulator
The Automatic Voltage Regulator (AVR) is an integral component
of the main controller. The AVR receives unregulated AC output
voltage from the stator excitation winding (DPE) through Wires
2 and 6. The AVR rectifies the AC voltage, and regulates it
based on the sensed voltage output of the stator. The regulated
DC excitation voltage (current) is then delivered to the rotor
windings through Wires 0 and 4, the brushes and slip rings.
The voltage regulator senses the AC output voltage of the
alternator through Wires 11 and 44.
The control panel provides both Under-voltage and Over-
voltage fault protection. During an over or under-voltage fault
condition the control panel will shut the unit down and display
the applicable Alarm.
•Under-voltage (0H6680A Controller) – If the Generator
voltage falls below 60% of rated (144V for a 240V unit) for
more than 5 seconds, the generator will shut down and an
ALARM will display.
•Under-voltage (0H6680B Controller through Rev B) – If the
Generator voltage falls below 85% of rated (204V for a 240V
unit) for more than 10 seconds, the generator will shut down
and an ALARM will display.
•Under-voltage (0H6680B Controller rev C and greater) –
Manual:
Cranking – If the starter disengages before a voltage
has developed in the stator, the controller will initiate a
shutdown alarm for “under-voltage.”
Running – If the Generator is running and voltage
output has been gone for 10 seconds, the controller
will initiate a shutdown alarm for “under-voltage.”
Auto:
Cranking – If the starter disengages before a
voltage has developed in the stator, the controller
will shutdown, pause for 15 seconds (countdown
displayed), and re-crank 3 additional times. If after
three crank attempts and the no voltage output
continues, the controller will initiate a shutdown alarm
for “under-voltage.”
Running – If the Generator is running and voltage
output has been gone for 10 seconds, the controller
will initiate a shutdown, pause 10 seconds, and
re-crank 3 times additional times. If after three crank
attempts and the no voltage output continues, the
controller will initiate a shutdown for “under-voltage.”
Note: The 3 crank attempts are cumulative. For example,
if the unit took two under-voltage re-cranks at startup, it
would only allow one additional re-crank for under-voltage.
•Over-voltage – If the Generator voltage rises above 110% of
rated (264V on a 240V unit) for greater than 3 seconds, or
if the Generator voltage rises above 130% of rated (312V on
a 240V unit) for greater than 0.2 seconds, the generator will
shutdown and an ALARM will display.
Main Line Circuit Breaker
The main line circuit breaker protects the Generator against
electrical overload. See the “Specifications” section for
specific amperage ratings.
LOAD SIDE
E1 E2
LINE SIDE
11 44
Figure 41. Main Line Circuit Breaker
Section 2.1
Description and Components
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