Woodward 723PLUS Technical Manual page 100

723PLUS Digital Marine Control
Symptom
Engine will not stabilize.
Control may be erratic or
vary with load.
90
Cause
1. Speed control dynamics
adjustments.
2. Improper linkage
adjustments.
3. Faulty dynamics #2
contact.
4. Erratic speed setting
devices.
5. Mechanical governor
interference/problem.
Test/Remedy
1. A dynamics adjustment problem generally appears as a
sinusoidal hunt or oscillation. There are several dynamics
adjustments that take effect during loaded or unloaded
conditions at different speeds. Verify the proper dynamics are
being adjusted at the proper time. Disable gain slope and/or
gain ratio functions to isolate problem. See dynamics
adjustments to correctly adjust 723PLUS control response.
2a. Make sure the actuator terminal shaft movement is
approximately 2/3 of the total actuator movement from no load
to full load. For most diesels, turbines, and fuel injected prime
movers, the actuator linkage should be linear. For the other
prime movers, a non-linear linkage should be used. See the
actuator manual regarding linkage arrangements.
2b. Make sure the linkage, ball-ends, and associated fuel rack
links are in good condition and not worn. Make sure the fuel
rack is not binding.
3. Dynamics #2 contact may be intermittently open or closing,
causing the dynamics selection to be intermittent. This is
especially true if an oil pressure or speed switch is used to
select between the two dynamics.
4. The speed setting device signal may be erratic, causing the
speed reference to move around erratically. The 723PLUS
control will attempt to follow the changing the speed reference.
View the speed setting input in control and verify that the
speed reference is stable.
5a. Often referred to as ballhead interference. The mechanical
ballhead governor and 723PLUS control speed settings are too
close to each other. The speed control governors (electrical
and mechanical) are attempting to control the engine speed at
the same time. Separate the two speed settings, lower
723PLUS control speed setting, or increase the mechanical
speed setting. There must be at least a 1.7% difference in
speed setting between the 723PLUS and the mechanical
governor.
5b. Possible actuator stability problem. Check actuator drive
rotation and actuator hydraulic pressure. Check condition of
actuator oil and supply system. For electric actuators, check
electronic driver module power supply, and associated wiring.
See the actuator manual for troubleshooting.
Manual 26482
Woodward