Question

(a) With the aid of a block diagram state the usual check points for maintenance of an electronic governor fitted to an auxiliary diesel engine. (8)

(b) An engine fitted with an electronic governor behaves erratically during load changes. Explain the possible causes. (8)

Answer 1

Part (a)

Part (b)

The problem may be with the governor or prime mover. To ascertain which, the governor actuator may be disconnected from the fuel pump control and the control lever held manually firm at a position that will maintain the required RPM. This should be done carefully when the ship is in open waters so that sudden tripping of the alternator due to low voltage does not expose the ship to a hazardous situation.

The electric load may be increased slightly when the RPM will drop which may be restored by operating the control lever manually. Next, the electric load is reduced slightly when the RM will rise which again may be restored manually. If the operation is still erratic, the problem is with the engine. If the operation is normal then the problem is with the governor.

If the problem is with the engine, the following may be the causes:

Fuel pump racks sticking
Air lock in the fuel system
Water in fuel
Fuel pump plungers occasionally sticking

If the problem is with the governor, the erratic operation may be due to following causes:

Actuator linkage sticking
The Magnetic Pick Up unit (MPU) not adjusted properly, slack and moving thus the air gap varying
Defective MPU
Governor not adjusted properly; too high a gain may cause hunting; gain should be reduced in such case
Loose electric connection
Other problems in the electronic circuitry, PCB

✓ Verified Model Answer (Text Solution)