Q1. Explain the principle of operation of synchronous Motors with a simple sketch. Where are synchronous motor used onboard? (16)
Q2. Briefly explain the principle of operation of Variable Frequency Drives (VFD). Discuss the
advantages and disadvantages of VFDs onboard merchant vessels? (16)
Q1.a) Explain three methods of overcurrent protection for electrical circuit. (8)
b) Explain with aid of diagram, the meaning of the term inverse current time characteristic (8)
Q3. With Respect to PLC’s used onboard ships:
a) Draw and explain the block diagram of a PLC. (8)
b) Name the onboard ship equipment where PLC’s are used. (4)
c) What are the advantages of PLC controllers over other type of controllers? (4)
Q5. With Reference to different types of transformers used onboard.
a) Discuss the basic principle of operation of a transformer (5)
b) Enumerate the different types of transformers used onboard also state their functions for which they are used. (5)
c) A 440/110 V single phase transformer supplies a load of 5kW at 0.8 power factor load. Calculate the primary and secondary currents. (Ignoring transformer power losses)? (6)
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