DieselShip's Online Content Library

Q5. With reference to the condition monitoring of electrical machinery:

(a) State TWO important parameters that may be recorded (8)

(b) Explain how the parameters are measured and what defects may be revealed (8)

Q2. Draw and explain the shape of the characteristic curve of a p-n junction diode in forward and reverse bias modes (16)

Q4. With the aid of a circuit diagram, explain how a Galvanometer can be used as an Ammeter. (16)

Q4. With the aid of a simple circuit diagram, explain the electrical distribution system for essential loads on board a cargo ship. (16)

Q4. Describe with the aid of a diagram the operation of the following components of electrical equipment and explain the purpose of each. (16)

a) Under voltage protection.

b) Miniature circuit breakers.

c) Reverse power tripping.

Q6. a) The current transformer (CT) and potential transformer (PT) or voltage transformer are both measuring devices. List their shipboard application. (6)

b) Sketch and describe any one type of current transformer. (10)

Q7. (a) Explain how excitation of the rotor is produced and supplied. (6)

Q7. (b) A one-turn armature coil has an axial length of 0.4m and a diameter of 0.2m. It is rotated at a speed 500 rev/min in a field of uniform flux density of 1.2 T. Calculate the magnitude of the e.m.f. induced in the coil. (10)

Q8. a) Describe in detail the method used to measure the capacitance of a capacitor.(6)

b) A circuit has a resistance of 3R and an inductance of 0.01 H. The voltage across its ends is 60V and the frequency is 50Hz. Calculate (a) the impedance. (b) the power factor (c) the power absorbed.(10)

Q9. a) Differentiate between resistance, induction and impedance in an A.C. circuit. (6)

Q9. b) A 4-pole, 32 conductor, Lap-wound DC shunt generator with terminal voltage of 200 V delivering 12 A to the load has Ra = 2 and field circuit resistance of 200 Ω. It is driven at 1000 RPM . Calculate

i) The flux per pole in the machine.

ii) If the machine has to be run as a motor with the same terminal voltage and drawing 5 A from mains, maintaining the same magnetic field, find the speed of the machine. (10)