Woodward 2301E, Инструкция по установке и эксплуатации, Страница: 40 / 182

2301E Digital Control Manual 26641
30 Woodward
Figure 3-1. Speed Control System
The digital control compares the numeric output of the speed sensor to the
numeric number of the speed reference at the summing junction. If the speed is
lower or higher than the reference, a response calculated by the PID
(Proportional-Integral-Derivative control) is sent to the actuator driver calling for
an increase or decrease in actuator current.
The actuator responds to the signal from the actuator driver by repositioning the
fuel or steam rack, changing the speed of the prime mover until the speed signal
and the reference are equal.
A failed speed signal circuit monitors the speed signal input. When no signal is
detected, it calls for minimum fuel. The minimum fuel signal is sufficient to cause
the actuator to go to the minimum position if not restricted. However, due to
linkage adjustment or other restrictions in the external system, minimum actuator
position may not permit prime mover shutdown.
For controls with actuator current of 20 to 160 mA, minimum fuel is defined as:

Actuator current less than 10 mA for forward-acting controls

Actuator current greater than 180 mA for reverse-acting controls
A contact to override the failed speed signal circuit can be connected in series
with one of the programmable discrete input terminals, programmed for this
function. Temporarily closing the contact overrides the failed speed signal circuit
as may be required for start-up.
Control Dynamics
RESET, GAIN, and ACTUATOR COMPENSATION adjust the control to
accommodate various types of prime mover systems. RESET adjustment affects
prime mover reaction time when recovering after a sudden load change. The
magnitude of the speed change resulting from a sudden change in load is
controlled by adjusting the GAIN. ACTUATOR COMPENSATION compensates
for the time the actuator and prime mover fuel system takes to react to signals
from the control. Idle Proportional Gain and Rated Proportional Gain are used to
stabilize the engine at idle speed and rated speed settings.