Class 4 (4th Engineer) MET 📅 Oct 2022

Exam Question

(a) Sketch and describe an arrangement for automatic connection of emergency batteries upon loss of main power. Include in your answer:

(i) Means of obtaining d.c charging supply from a.c mains (3)

(ii) A method of maintaining charge on lead acid batteries (3)

(iii) The arrangement to check the batteries operate at a loss of main power. (2)

(iv) The length of time for which emergency battery of passenger and cargo ship must provide power (2)

(b) write short notes on primary and secondary cells. (6)

Reference Answer

### (a) Automatic Connection of Emergency Batteries
#### Description of Arrangement
The system is designed to provide an uninterruptible power supply (UPS) to essential services in the event of a main power failure (blackout). The core of the system is an Automatic Transfer Switch (ATS) or a set of interlocked contactors controlled by an under-voltage relay.
1. **Normal Operation**: The main power from the ship's generators supplies the Main Switchboard (MSB). The Emergency Switchboard (ESB) is fed from the MSB via a tie-line circuit breaker. A battery charger, also powered from the MSB (or ESB), maintains the emergency batteries in a fully charged state.

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