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Q9. Describe, with the aid of a circuit diagram, the operation of an automatic voltage regulator (AVR) which employs the use of thyristors. (10)

Q2. (a) Explain EACH of the following control terms:

(i) cascade; (2)                              (ii) split range. (2)

(b) Describe, with the aid of a sketch, a control system that may be enhanced by the inclusion of cascade control. (6)

Q4. State the inspections, instructions and maintenance that should be carried out on main sea water pipelines, strainers and ship's side valves to minimise the risks of engine room flooding. (10)

Q5. (a) Describe TWO systems of priming centrifugal pumps. (6)

(b) List the advantages of EACH of the priming methods described in part (a). (4)

Q7. With reference to the lubrication of refrigeration compressors:

(a) state the advantage of using fully synthetic oils; (2)

(b) explain why oil may be carried over from the compressor; (3)

(c) describe a device which returns oil from the compressor discharge to the compressor sump; (3)

(d) state TWO reasons why an accumulation of oil in the evaporator is undesirable. (2)

Q11. With reference to large electrical transformers on board ships:

(a) state where these transformers may be used; (1)

(b) state a typical efficiency range for a transformer; (1)

(c) state the regulations pertaining to transformers; (3)

(d) state the protective devices that are fitted; (2)

(e) describe the maintenance requirements. (3)

Q11. (a) With reference to an alkaline battery cell:

(i) describe a typical cell, stating the materials used; (4)

(ii) describe the electro-chemical process that takes place during discharge and charge. (2)

(iii) state the effect of overcharge. (2)

(b) State the advantages of an alkaline cell compared with a lead acid cell. (2)

13. Explain, with the aid of a mid-ship half sectional sketch of a container ship, how strength is built into this type of vessel whilst still allowing access to the cargo holds. (10)

Q12. (a) Describe, with the aid of sketch, how a hydraulically operated folding hatch cover opens and closes. (7)

(b) Explain how the water tightness and security of the hatch cover sketched in part (a) can be ascertained before proceeding to sea. (3)

Q13. (a) Explain why fatigue cracks occur in a ship's hull, stating the locations where they may be found. (3)

(b) Describe the hull inspection that should be carried out m drydock to ascertain the maintenance and repairs that may need to be carried out. (7)