Woodward ProAct I, Product Manual

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ProAct I/II Manual 04121
14 Woodward
This feature eliminates the potentially damaging jiggle of the actuator and fuel
system. The control automatically increases gain by an adjustable gain ratio
when speed error exceeding an adjustable window occurs, or is anticipated to
occur, based on measurements of the instantaneous rate of change of the entire
engine. Operation with base gain is restored once the control senses the return
to steady-state speed. The Window Width speed is a ± value, centered around
zero speed error.
Variable Dynamics
The control is designed to compensate for non-linear fuel systems and changes
in engine dynamics with load. The control gain is mapped as a function of
actuator position.
Four break points work with four gain settings to map the actuator against
expected non-linear conditions. This provides optimal dynamics and smooth
steady-state operation for all conditions from no load to full engine load. The four
different response rates are achieved by the creation of four different gain
settings. Gas engine installations will usually require all four gain settings for
different fuel flows, especially if the actuator is direct-coupled to the butterfly.
Most diesel applications will need only one or two of the gain settings with the
break points of the other settings moved up out of the way (set to 100%).
Fuel Limiters
Start Fuel Limit
The ProAct control has a start fuel limiter to provide smoother transitions and
less over-fueling during start-up. The limiter is set to provide the desired position
during starts. The control will reduce the fuel when the start speed set point is
reached as required to control engine speed, but will not exceed the Start Limit.
The Start Fuel limit is removed when the engine speed reaches the Start Speed
set point.
The Start Fuel limit is combined with a user-tunable ramp that will increase the
Start Fuel limit at a programmable rate while the engine speed is below the Start
Speed set point. This ramp is designed to allow for easier starting of the engine
during various temperature conditions, such as a cold start, which may require an
increase in fuel.
Maximum Fuel Limit
This programmable actuator position limit is in place when rated speed is
selected. This is the maximum actuator position setting allowed for steady-state
full load.