Exam Question
(a) With the aid of a block diagram describe the operation of an electronic governor fitted to an auxiliary diesel engine. (10)
(b) State the reasons for fitting a droop governor to a diesel generator. (6)
Class 4 (4th Engineer)
MEKM
📅 Mar 2025
Reference Answer
### (a) Operation of an Electronic Governor
An electronic governor is a closed-loop control system designed to maintain the speed of a diesel engine at a desired setpoint, irrespective of load variations. Its operation is based on the continuous comparison of the engine's actual speed with a reference speed, and using the error to modulate fuel delivery.
#### 1. System Components
* **Speed Sensing Unit:** This is typically a Magnetic Pickup Unit (MPU) installed adjacent to the engine flywheel's ring gear. It consists of a permanent magnet with a coil wound around it. As the gear teeth pass the MPU, they alter the magnetic flux, inducing an AC voltage pulse in the coil. The frequency of these pulses is directly proportional to the engine's rotational speed (RPM).
An electronic governor is a closed-loop control system designed to maintain the speed of a diesel engine at a desired setpoint, irrespective of load variations. Its operation is based on the continuous comparison of the engine's actual speed with a reference speed, and using the error to modulate fuel delivery.
#### 1. System Components
* **Speed Sensing Unit:** This is typically a Magnetic Pickup Unit (MPU) installed adjacent to the engine flywheel's ring gear. It consists of a permanent magnet with a coil wound around it. As the gear teeth pass the MPU, they alter the magnetic flux, inducing an AC voltage pulse in the coil. The frequency of these pulses is directly proportional to the engine's rotational speed (RPM).
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