Exam Question
(a) Sketch a diesel electric propulsion arrangement for a ship (8)
(b) Describe the operation of the propulsion arrangement sketched in (a), including in your description how reversal of the propulsion motor is achieved (8)
Class 4 (4th Engineer)
MET
📅 May 2024
Reference Answer
### (a) Sketch of a Diesel Electric Propulsion Arrangement
A diesel-electric propulsion system decouples the prime movers (diesel engines) from the propeller, allowing the diesel engines to operate at optimal speeds to generate electricity, which then powers an electric motor directly coupled to the propeller. For the purpose of describing speed control and reversal as historically taught and for 'Surveyor-Grade' detail, a Ward-Leonard control system for a DC propulsion motor is detailed.
**Main Components to be Illustrated:**
1. **Diesel Generators (DG Sets):** Comprising high-speed diesel engines (prime movers) driving electrical generators. In a Ward-Leonard system, these would typically be DC generators, though AC generators feeding rectifiers are also common. Multiple DG sets are usually installed for redundancy, load sharing, and efficient part-load operation.
A diesel-electric propulsion system decouples the prime movers (diesel engines) from the propeller, allowing the diesel engines to operate at optimal speeds to generate electricity, which then powers an electric motor directly coupled to the propeller. For the purpose of describing speed control and reversal as historically taught and for 'Surveyor-Grade' detail, a Ward-Leonard control system for a DC propulsion motor is detailed.
**Main Components to be Illustrated:**
1. **Diesel Generators (DG Sets):** Comprising high-speed diesel engines (prime movers) driving electrical generators. In a Ward-Leonard system, these would typically be DC generators, though AC generators feeding rectifiers are also common. Multiple DG sets are usually installed for redundancy, load sharing, and efficient part-load operation.
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