Brochure

8
Options and Accessories
Permanent Magnet Generator
(PMG)
PMG supplies continuous power to the exciter
through the voltage regulator in order to
maintain up to 300% short circuit current from
the alternator during a fault condition. It provides
full exciter power, regardless of the generator
voltage.
Neutral Grounding Resistor (NGR)
The NGR acts to limit generator fault current to a low level when a phase-to-
ground fault occurs. It also serves to protect the generator from excessively high
magnetic stresses and temperatures caused by high fault currents. The NGR is
time-rated.
AVR
EXCITER
ARMATURE
BRUSHLESS
EXCITER
SYNCHRONOUS
GENERATOR
ROTOR
FIELD
STATOR
WINDINGS
CT
PT
GCB
SYSTEM
BUS
NGR
1000A
EXCITER
FIELD
SETPOINT
INPUT
AUTOMATIC VOLTAGE REGULATOR
(DECS UNIT OR EQUIVALENT)
CT
PT
FIELD
OUTPUT
PMG
POWER IN
IDC
(3A to 15A)
DIODE
RECTIFIER
10 or 30
0
8
EXE
PERMANENT
MAGNET
GENERATOR
EXCITER
FIELD
(PERM. MAGNET)
PMG
ARMATURE
10
or
30
CT1 (1)
NEUTRAL
CURRENT
13,800:120/240 V
10A/10 sec
50/5A, C10
HEATER
RS
AVR
EXCITER
ARMATURE
BRUSHLESS
EXCITER
SYNCHRONOUS
GENERATOR
ROTOR
FIELD
STATOR
WINDINGS
CT
PT
GCB
SYSTEM
BUS
NGR
1000A
EXCITER
FIELD
SETPOINT
INPUT
AUTOMATIC VOLTAGE REGULATOR
(DECS UNIT OR EQUIVALENT)
CT
PT
FIELD
OUTPUT
PMG
POWER IN
IDC
(3A to 15A)
DIODE
RECTIFIER
10 or 30
0
8
EXE
PERMANENT
MAGNET
GENERATOR
EXCITER
FIELD
(PERM. MAGNET)
PMG
ARMATURE
10
or
30
CT1 (1)
NEUTRAL
CURRENT
13,800:120/240 V
10A/10 sec
50/5A, C10
HEATER
RS
Automatic Voltage
Regulation (AVR)
The AVR utilizes a fast response
microprocessor to control its AC to DC
converter power stage output that
provides excitation to the generator
to regulate the dierence between
the generator stator voltage reference
set point and feedback signal to
zero. Reactive power sharing during
parallel operation of generator with
other generators or a power system
is achieved by the use of droop
compensation where the voltage
feedback signal is increased by
typically 0% to 5% as lagging reactive
load current increases from 0% to
100%. The following four operating
control modes with a bumpless
transfer between modes are available
to suit the site requirements:
• Sequence of events recording
& oscillography, which is useful
during commissioning diagnostics
• AVR automatic voltage regulation
(with switchable reactive power
droop compensation for basic
parallel operation)
• Generator PF power factor control
(for connection to large power
system)
• Generator VAR reactive power
control (for connection to large
power system)
• Brushless exciter eld current
(manual mode) regulation
Other functions of the AVR include:
• Voltage soft-start build up
• Minimum and maximum excitation
and stator current limiters