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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)

Q6. a) Describe the working of a single-phase full wave rectifier with a resistive load. Draw the load voltage and current waveforms. (8)

b) Diode half wave rectifier supply a resistive load of 100Ω from a 100 V ac r.m.s voltage source. The diode is a resistance of 5Ω during conduction state. Calculate

i) The DC output voltage

ii) DC average load 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)

Q9. With reference to MARPOL Annex IV
a) Draw a biological sewage treatment plant and explain the principle of operation. (8)
b) Periodical maintenance and checks and tests required to be done to verify the effectiveness of the above system. (8)

Q8. Explain in detail a fixed gas fire extinguisher system, indicating the required quantity of the fire-extinguishing medium, the controls required for the system installation requirement and training required to bring the system to be readily operated. (16)

Q8. 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)