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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)

Q2. a) Briefly Explain Intrinsically safe circuit and Explosion proof circuit. (6)

b) What is EXD and EXI? Where they are used onboard ship. (3)

c) What all Intrinsically safe equipment used on Deck, explain how they are Intrinsically safe. (3)

d) What is Zener Barrier? How flame and explosion contained inside the enclosure. (4)

Q2. a) Explain why it is necessary to have reverse power protection for alternators intended for operation. (6)

b) (i) Sketch a reverse power trip. (5)

(ii) Briefly explain the principle on which the operation of this power trip is based and how tripping is activated. (5)

Q4. With respect to circuit breakers:

a) Compare the effectiveness of a current limiting circuit breaker with that of a HRC fuse. (6)

b) A coil having a resistance of 10 ohm and an inductance of 0.15 H is connected in series with a capacitor across a 100 V, 50 Hz supply. If the current and the voltage are in phase what will be the value of the current in the circuit and the voltage drop across the coil? (10)

Q5. With reference to adjoining circuit calculate following

a) Current in each branch of circuit (8)

b) Total current (8)

Q6. A 100 KVA, 2400/240 V, 50 Hz, 1-phase transformer has no- load current of 0.64 A and a core loss of 700 W, when its high voltage side is energized at rated voltage and frequency . calculate the two components of no-load current. If this transformer supplies a load current of 40 amp at 0.8 lagging power factor at its low voltage side, determine the primary current and its power factor. Ignore leakage impedance drop. (16)

Q7. a) Describe the routine tests required for self-contained breathing apparatus sets (8)

b) Describe the procedure to be adopted to find missing personnel in a smoke-filled accommodation area. (8)

Q8. a) Describe CO2 Fixed fire fighting system for machinery spaces and cargo spaces of a bulk carrier. (8)

b) Explain safety precautions taken prior to release of CO2 to the engine room. (8)

Q7. With reference to entry into enclosed spaces onboard:
a) Define “Enclosed space” and give example of enclosed spaces onboard (6)
b) Describe the checks done for testing the atmosphere inside such enclosed spaces. (5)

c) Explain safety precautions taken prior to entry into enclosed spaces onboard vessel. (5)