Relay Control - Deif GPC-3 Designers Reference Handbook

GPC-3 DRH 4189340587 UK

6.3 Relay control

45Hz
Fix up signal Up pulse
The regulation with relays can be split up into five steps.
# Range Description
1 Static range Fixed up
signal
2 Dynamic Up pulse
range
3 Deadband No reg.
area
4 Dynamic Down pulse
range
5 Static range Fixed down
signal
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 deadband area, the pulse is as short as it can get. This is the adjusted
time "GOV ON time". The longest pulse will appear at the end of the dynamic range (45 Hz in the example
above).
DEIF A/S
Regulator
output
50Hz 55Hz
No reg. Down pulse
Comment
The regulation is active, but the increase relay will be constantly activa-
ted because of the size of the regulation deviation.
The regulation is active, and the increase relay will be pulsing in order to
eliminate the regulation deviation.
In this particular range no regulation takes place. The regulation accepts
a predefined deadband area in order to increase the lifetime of the re-
lays.
The regulation is active, and the decrease relay will be pulsing in order
to eliminate the regulation deviation.
The regulation is active, but the decrease relay will be constantly activa-
ted because of the size of the regulation deviation.
Hz
Fix down signal
PID controller
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