8290-186 WOODWARD

Failed Speed Signal Override 

Circuits in the 2301A Speed Control constantly monitor the signal from the MPU. 

Should this signal be below a minimum threshold the control sends a minimum 

fuel signal to the actuator (maximum fuel signal on a reverse acting control). 

Manual 82020 2301A Speed Control 

Woodward 11 

Before start-up of the prime mover, the speed signal is nonexistent, activating the 

failed speed signal circuit. On units with cranking motors, the cranking speed is 

usually sufficient to provide a speed signal, so an override contact is not needed 

for starting. On some steam turbine systems, the Close for Override of Failed 

Speed Signal contact must be closed to allow the actuator to open and provide 

steam for starting. 

The failed speed-signal override switch should be a momentary switch so the 

failed-speed-sensor circuit will be enabled after start-up. 

Idle/Rated Ramp Contact 

Connect a single-pole, single throw switch to terminal 5 as shown on the 

appropriate plant-wiring diagram. Close the contact for rated, open for idle. Oil 

pressure is often used to close this contact. When closed, 10 to 40 Vdc is applied 

to terminal 5, and the prime mover can be operated at a speed higher than idle. 

When the contact is open, the voltage is removed from terminal 5, and the prime 

mover's speed decelerates to idle. The ramp rate applies only to the acceleration 

mode. When the ramp time potentiometer is full cw the ramp time from idle to 

rated is 22 ±4 seconds. When the ramp time potentiometer is fully ccw (be 

careful not to overtorque the pot), the ramp rate is less than 1 second from 

idle to rated. 

The ramp time from rated to idle is always less than 1 second, regardless of the 

setting of the ramp-time potentiometer. 

Actuator Output 

The actuator wires connect to terminals 9 (+) and 10 (–). Use shielded wires with 

the shield connected to the grounded post on the panel. Do not connect the 

shield to the actuator or to any other point. The shield must have continuity the 

entire distance to the actuator and must be insulated from all other conductors. 

Some 2301As may be used to operate prime movers in tandem by wiring the two 

actuators in series as shown in detail A of the wiring diagram. Tandem operation 

with a single 2301A control requires that the two engines provide identical power 

response to identical current signals to each of the actuators.