ECON-4, SW version 1.4 rev.1, ©ComAp – March 2016 Draft 36
ECON-4 Reference guide.pdf
Speed governor function in parallel mode
When engine is in parallel to Mains, Econ4 works just as amplifier and converts Speed request signal
to Gas Dose signal according Speed/Fuel line as follows
Transition to parallel from zero local load.
When engine is running without load, speed request from controller is in bias position and engine has
a throttle in Idle position. So if those values are properly set in to ECON4 setpoints while going to
parallel, engine startso to run in SGO Bias and Idle Fuel point on Speed/Fuel line. When request for
load is increased in controller, Speed request is increased and throttle is opened and vice versa.
Transition to parallel from non-zero local load.
There could be situation in SPtm for example, when just GCB is closed and generator supply a local
load. So MCB is opened and GCB is closed and PID with Load parameters is used to control speed
and Throttle position. It is clear than Throttle is not in Idle position but on higher position. Now after
synchronization, MCB is closed, throttle stays in the same position because no Higher Power is
generated just after synchronization and Actual speed request is in Bias position because no power
control has been done in previous stage. So there is difference between actual speed request and
speed request corresponding to actual throttle position. This difference is called Speed request offset
and we keep it to make transition bumpless. When controller increase speed request to provide more
power to Mains, we move throttle to higher position on the Speed/fuel line and it works fine. But we
can not keep speed request offset all time, because when controller decrease speed request throttle
would go to zero position and even to negative value (theoretically). So we keep Speed request offset
just for one minute from MCB and GCB breaker closing and then starts to decrease this offset. This
will move throttle down, but controller will notify decreasing of power and increase speed request.
After a while, using this mechanism Speed request offset is zero and actual throttle position respects
speed request and Speed/fuel line.
Speed request offset is decreased according ramp, which is set in setpoint SGOoffsetRamp. Time in
this setpoint is time needed to change Speed request offset from 10V to 0V.
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