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Q2. a) Sketch a circuit diagram of a push button direct online contactor starter for a three phase Incorporating overload and short circuit protection. (8)

b) Indicate, on a sketch of the typical characteristic curves of current and torque against Speed, disadvantages of a direct online start squirrel cage induction motor. (8)

Q3. With reference to the provision of a shore electrical supply to a ship:

a) Sketch an arrangement for taking A.C. Shore supply and checks to be carried out prior taking shore connection? (8)

b) Describe the methods of safely connecting the arrangement sketched in (A) to the shore supply? (8)

Q3. a) Sketch a main engine shaft driven generator arrangement with an electronic system for frequency correction. (8)

b) Describe the operation of the generator arrangement sketched in (a). (8)

Q4. A) Explain the potential hazards if liquid-cooled transformers are used. (6)
b) What are the losses in transformers? Mention the various factors which affect these losses. In a 25 KVA, 3300/233 V, single phase transformer, the iron and full-load Cu. Losses are respectively 350 and 400 w. Calculate the efficiency at half-full load 0.8 power factor. (10)

Q5. a) List the factors that determine the starting torque of the three-phase induction motor. How does this torque generally compare with the value of the rated torque? (6)
b) The low-voltage release of an a.c. motor-starter consists of a solenoid into which an iron plunger is drawn against a spring. The resistance of the solenoid is 35 ohm. When connected to a 220 V, 50 Hz, a.c. supply the current taken is at first 2 A, and when the plunger is drawn into the “full-in” position the current falls to 0.7 A. Calculate the inductance of the solenoid for both positions of the plunger, and the maximum value of flux-linkages in weber-turns for the “full-in” position of the plunger. (10)

Q6. A) With the aid of delta and star connection diagrams, state the basic equation from which the delta-star and star- delta conversion equation can be derived. (6)
B) Three batteries A, B, and C have their negative terminals connected together. Between the positive terminals of A and B there is a resistor of 0.5 ohm and between B and C there is a resistor of 0.3 ohm
Specifications of the three batteries are given below.
Battery A 105 V, Internal resistance   0.25 ohm
Battery B 100 V, Internal resistance   0.2 ohm
Battery C   95 V, Internal resistance   0.25 ohm
Determine the current values in the two resistors and the power dissipated by them. (10)

Q7. (a) As per Annex II of MARPOL. Describe categories in which substances are divided. (8)

(b) Give conditions under which they can be discharged outside special areas? (8)

Q8. With reference to “ISM code” write short notes on. (16)

a) Management Review

b) Advantage of drills and procedure

c) Master overriding authority.

d) Advantage of internal audit.

Q9. a) Sketch and describe a total flooding CO₂ gas system suitable for the protection of machinery spaces. (6)

b) State, with reasons, which valve should be operated first in the system shown in (a) (4)

c) State the periodic maintenance required on the system. (6)