Exam Question
(a) What is the purpose of Preferential Tripping system on ship's electrical network? (6)
(b) Explain the various stages of preferential trips with the loads connected to those stages (10)
Class 4 (4th Engineer)
MET
📅 May 2023
Reference Answer
### (a) Purpose of the Preferential Tripping System
The primary purpose of a Preferential Tripping System on a ship's electrical network is to **prevent a total blackout** during a sustained generator overload condition. It is a critical safety system that ensures the continuous supply of power to essential services required for the safe navigation and operation of the vessel.
Its key objectives are:
1. **Blackout Prevention**: In an overload scenario (e.g., generator load exceeding 100% of its rated capacity), the prime mover (diesel engine) will start to slow down, causing a drop in frequency. If uncorrected, this would eventually lead to the generator's own overcurrent protection tripping the main circuit breaker, resulting in a complete loss of power.
The primary purpose of a Preferential Tripping System on a ship's electrical network is to **prevent a total blackout** during a sustained generator overload condition. It is a critical safety system that ensures the continuous supply of power to essential services required for the safe navigation and operation of the vessel.
Its key objectives are:
1. **Blackout Prevention**: In an overload scenario (e.g., generator load exceeding 100% of its rated capacity), the prime mover (diesel engine) will start to slow down, causing a drop in frequency. If uncorrected, this would eventually lead to the generator's own overcurrent protection tripping the main circuit breaker, resulting in a complete loss of power.
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