4
Electric Power Generation
2019.10 / e
Installation and maintenance
R180
AVR
5599 en -
1 - GENERAL DESCRIPTION
The R180 is a fully solid- state automatic
voltage regulator (AVR) which is used for
excitation of a brushless alternator powered
by a Permanent- Magnet (PMG) exciter or
by auxiliary windings.
The alternator voltage between phases V- W
is sampled, processed and converted to a
direct current value. This signal is compared
to the reference value which is internally
generated depending upon the voltage
setting. The comparison is made by a PID
controller, which controls the alternator
excitation. The power circuit uses a pulse
width modulated (PWM) IGBT circuit to
adjust the field current, which gives a good
dynamic/transient response.
It takes a 1 and 5 A signal from a droop
current transformer in U phase to give a
voltage droop which allows the alternator to
operate in parallel.
The R180 has an accessory input, which
can be used as a remote potentiometer
terminal when connected to a 1 KΩ
potentiometer or takes ± 4.5 VDC in order to
change the terminal voltage.
It has an under frequency voltage roll- off
function to prevent alternator overfluxing in
the event of underspeed operation. The
AVR has a potentiometer for setting the
knee- point for under frequency roll- off and
a 50 Hz/60 Hz selection jumper. This jumper
makes it easy to select the AVR frequency
for a 50 Hz/60 Hz alternator.
The AVR output is limited to 6 A. This limiter
is delayed type so that it does not interfere
with field forcing. In the event of loss of the
sensing input, the AVR provides 9 A DC
excitation current for 5 seconds and
reduces the excitation current.
The R180 is triggered from the alternator
remanent voltage.