The regulation with relays can be split up into five steps.
# Range Description Comment
1 Static range Fix up signal
The regulation is active, but the increase relay will be constantly activated because of the
size of the regulation deviation.
2 Dynamic range Up pulse
The regulation is active, and the increase relay will be pulsing in order to eliminate the
regulation deviation.
3 Dead band area No reg.
In this particular range no regulation takes place. The regulation accepts a predefined dead
band area in order to increase the lifetime of the relays.
4 Dynamic range Down pulse
The regulation is active, and the decrease relay will be pulsing in order to eliminate the
regulation deviation.
5 Static range Fix down signal
The regulation is active, but the decrease relay will be constantly activated because of the
size of the regulation deviation.
As the drawing indicates, the relays will be fixed ON if the regulation deviation is big, and they will be pulsing if it is closer to the set
point. In the dynamic range the pulses get shorter and shorter when the regulation deviation gets smaller. Just before the dead band
area the pulse is as short as it can get. This is the adjusted time "GOV ON time"/("AVR ON time"). The longest pulse will appear at
the end of the dynamic range (45 Hz in the example above).
4.7.1 Relay adjustments
The time settings for the regulation relays can be adjusted in the control setup. It is possible to adjust the "period" time and the "ON
time". They are shown in the drawing below.
Adjustment
Description Comment
Period time Maximum relay time The time between the beginnings of two subsequent relay pulses.
ON time Minimum relay time
The minimum length of the relay pulse. The relays will never be activated for a shorter time
than the ON time.
As it is indicated in the drawing below, the length of the relay pulse will depend on the actual regulation deviation. If the deviation is
big, then the pulses will be long (or a continued signal). If the deviation is small, then the pulses will be short.
PERIOD PERIOD PERIOD PERIOD PERIOD
t [sec]
Relay ON
HIGH <DEVIATION> LOW
ONONONONON
DESIGNER'S HANDBOOK 4189341275A EN Page 81 of 196
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