DieselShip's Online Content Library

Q3. Explain the matching of an induction electric motor to a pump required for main circulating duty, with the aid of pump characteristic and torque/ship diagrams (16)

Q1.a) Explain the meaning of the term power factor correction (4)

b) State advantages of power factor correction (4)

c) Explain, with the aid of a circuit diagram, how power factor correction can be effected in a three phase circuit using capacitors. (4)

d) Explain one method other than the use of capacitors by means of which power factor correction may be effected. (4)

Q3. What is soft starting of an Induction Motor? Describe with a circuit using thyristors used for soft starting. Discuss its advantages and disadvantages. (16)

Q4. (a) Explain the significance of the root- mean- square value of an alternating current or voltage waveform. Define the form factor of such a wave form.  (6)

(b) A total load of 8000 kW at 0.8 power factor is supplied by two alternators in parallel. One alternator supplies 6000 kW at 0.9 power factor. Find the kVA rating of the other alternator and the power factor. (10)

Q5. A) By means of a schematic circuit diagram illustrate the peak rectifier. If the supply voltage is v(t) = Vm Sinwt, what is the voltage across the load resistor? (6)

b) A battery-charging circuit is shown below in fig. The forward resistance of the diode can be considered negligible and the reverse resistance infinite. The internal resistance of the battery is negligible. Calculate the necessary value of the variable resistance R so that the battery charging current is 1.0 A. (10)

Q6. A) What is back emf? Derive the relation for the back emf and the supplied voltage in terms of armature resistance. (6)

b) A three-phase induction motor is wound for four poles and is supplied from a 50 HZ system.

Calculate:

(i) The synchronous speed

(ii) The speed of the rotor when the slip is 4 percent

(iii) The rotor frequency when the speed of the rotor is 600 r/min. (10)

Q7. Explain the cargo hold fire detection system used on ships. Discuss the maintenance procedures for this system and outline the steps taken when a fire is detected in the cargo hold. (16)

Q8. Discuss the following with respect to international safety Management (ISM) Code: (16)

a) Management Review and its agenda

b) Functional requirement and objectives of code.

c) Master responsibility and Authority.

d) Certification and periodical verification.

Q9. With reference to free fall lifeboat of an ocean-going ships:
a) Periodical maintenance, tests and checks on lifeboat and releasing gear. (6)
b) Secondary means of lowering. (5)
c) Lifeboat Drills. (5)