The MX321 is a three phase, thyristor type Automatic Voltage
Regulator (AVR) and forms part of the excitation system for a
In addition to regulating the generator voltage, the AVR circuitry
includes protective features to ensure safe reliable control of
the generator. Excitation power is derived from a permanent
magnet generator (PMG) to guarantee low Radio Frequency
Interference (RFI) and immunity from thyristor type loads.
The AVR is linked with the main stator windings and controls
the power fed to the exciter stator and hence the main rotor to
maintain the machine output voltage within the specified limits,
compensating for load, speed, temperature and power factor
of the generator.
Soft start circuitry is included to provide a smooth controlled
build up of generator output voltage.
Sustained overvoltage caused by open circuit sensing terminals
is avoided by overvoltage detection circuitry which provides
internal shutdown of the AVR output device.
A frequency measuring circuit continually monitors the
generator output and provides underspeed protection of the
excitation system by reducing the generator output voltage
proportionally with speed below a presettable threshold. A
further enhancement of this feature is an adjustable volts/Hz
slope to improve frequency recovery time on turbo charged
Current limiting may be included to allow control over the
amount of short circuit current flowing during three phase and
single phase short circuits on the generator output.
Uncontrolled over excitation is limited to a safe period by internal
shutdown of the AVR output device. This condition remains
latched until the generator has been stopped.
For complete protection, a circuit breaker option is available
providing circuit isolation in event of a short circuit power device.
Provision is made for the connection of a remote voltage trimmer
allowing the user fine control of the generator’s output.
Accessories are available for this AVR. Please refer to factory
for further details.
*The stated voltage regulation may not be maintained in the presence
of certain transmitted radio signals. Any change in regulation will fall
within the limits in Criteria B of EN50082-2.