DieselShip's Online Content Library

Q1. With respect to the High Voltage power systems installation, explain the different types of circuit breaker that are used, comparing them on merits and de-merits. Describe the theory of arc phenomenon and the mechanism fitted to mitigate the arc. (16)

Q2. What are the condition for producing sustained oscillations? Classify oscillations with respect to frequency range, principle involved, etc. It is possible to produce oscillations with RC networks in phase shift oscillator. Discuss in detail. (16)

Q3. With reference to the condition monitoring of electrical machinery:
(a) State the important parameters that may be recorded. (8)
(b) Explain how the parameters are measured and what defects may be revealed. (8)

Q4. (a) Describe the normal criteria used for setting thermal protection relays and their

advantage compared to magnetic types. (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 Ω. When connected to a 220V, 50Hz, a.c. supply the current taken is at first 2A, and when the plunger is drawn into the ‘full-in” position the current falls to 0.7A, 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)

Q5. (a) State briefly. The meaning of the expressions ‘star-connected’ as applied to three -phase a.c. practice. What is the ratio of the maximum line voltage to the maximum phase voltage in each case. (6)
(b) Determine the line current taken by a 440 V, three-phase, star-connected motor having an output of 45 Kw at 0.88 (lagging) power factor and an efficiency of 93 per cent. (10)

Q6. (a) Why is it important to maintain high efficiency of operation and low values of voltages regulation for power transformers? (6)
(b) A 20 KVA, 2000/220V, single-phase transformer has a primary resistance of 2.1 Ω and a secondary resistance of 0.026 Ω, The corresponding leakage reactance’s are 2.5 Ω and 0.03 Ω. Estimate the regulation at full load under power-factor conditions of;
(i)  unity

(ii) 0.5 (lagging)

(iii) 0.5 (Leading) (10)

Q7. Write short notes on following:
(a) Role of Classification Society on ship who act as Recognized Organization. (6)
(b) Enhanced survey program (ESP) and its applicability (5)
(c) Condition of Class (COC). (5)

Q8. Name various statutory Certificates and Documents to be carried on board Chemical Tankers giving reference to the conventions and justify for their requirement. (16)

Q9. With respect to the hazardous areas of tankers.
(a) Explain the term flameproof (Ex d) for electrical equipment. (6)
(b) State the type of electrical equipment that would be protected in this way. (5)
(c) List likely defects of flameproof equipment. (5)