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Q10. With reference to 3-phase transformers;

(a) Discuss the essential and desire conditions to be fulfil for operating two three-phase transformers in parallel.

(b) What are the advantages of transformer bank of three 1-phase transformers over a unit three phase transformer of the same kVA rating?

(c) In a 25 kW, 3300/233V, 1- phase transformer the iron and full load copper losses are 350 watts and 400 watts respectively. Calculate the efficiency  at half load, 0.8 p.f.

Q1. Two Diesel Generators running in parallel with D/G # 1 having 2000 KW capacity having 3 % speed droop setting and D/G # 2 having 2000 KW capacity with 4% speed droop settings. The frequency for Diesel Generator on no load has been set at 62 Hz.

A) Calculate the load on each Diesel Generator KW if total ship load is 1000 KW. B) Justify the load difference shared by both Diesel Generator.

Q8. A. What is slip? What are the factors on which the torque or an induction motor depends? B. A 220-V, 3-  4-pole, 50Hz, Y-connected induction motor is rated 3.73 KW The equivalent circuit parameters are: R1=0.45 , X1=0.8 , R2=0.4 , B0=1/30ohm. The stator core loss is 50W and rotational loss is 150W. For a slip of 0.04, find (i) input current (ii) p.f. (iii) air-gap power (iv) mechanical power (v) electro-magnetic torque (vi) output power and (vii) efficiency?

Q8. A. Explain the purpose of interpoles and state their magnetic polarity relative to the main poles of both generators and motors. (6)

B. A 200V, long-shunt compound-wound generator has a full-load output of 20kW. The various resistances are as follows: armature (including brush contact) 0.15 ohm, series field 0.025 ohm, interpole field 0.028 ohm, shunt field (including the field-regulator resistance) 115 ohm. The iron losses at full load are 780W, and the friction and windage losses 590W. Calculate the efficiency at full load. (10)

Q10. (a) What is meant by Quasi Propulsive Coefficient?

A ship of 15000 tonne displacement has mechanical efficiency of the machinery is 83%, shaft losses 6%, propeller efficiency 65% and QPC 0.71. At a particular speed the thrust power is 2550 KW. Calculate: (i) Indicated Power; (ii) Effective power.

Q8. A. Why is it important in a tender ship to keep the double bottom tanks pressed up?

B. A ship of 6000 tonne displacement has a wetted surface area of 2500 m2 and a speed of 15 knots.

(i) Calculate the corresponding speed and wetted surface area of as similar ship of 2000 tonne displacement.

(ii) If the ship resistance is of the form R=0.45 S V1.83 N; find the resistance of the 6000 tonne Ship.

Q8. A box shaped vessel is 80 m long, 12 m wide and floats at a draught of 4m.

A full width midships compartment 15 m long is bilged and this results in the draught increasing to 4.5 m. Calculate EACH of the following,

(a) The permeability of the compartment;

(b) The change in metacentric height due to bilging.

Q4. A ship of displacement 11000 tonne has a length 120 m, breadth 16 m, and even keel draught of 5.5 m in sea water of density 1025 kg/m3. The area of the waterplane is 1440 m2 and the second moment of area of the waterplane about a transverse axis through midships is 1.2 × 106 m4 with the LCF at midships. The ship has a full depth empty rectangular compartment of length 12 m and breadth 10 m.  The center of the compartment is on the centerline of the ship 40 m forward of midships.

Calculate the end draughts after the compartment is bilged.

Q6. A. Explain how wave profile affects the shear force and bending moment curves. B. A ship 125m long displaces 12000 tonne. When a mass of 100 tonnes is moved 75m from forward to aft there is a change in trim of 65 cm by the stem. Calculate - MCTI cm; The longitudinal metacentric height; The distance moved by the centre of gravity of the ship.

Q10: A. Explain the term volumetric heeling moments. B. A box barge 33m long and 5.5m wide has a light displacement and KG of 216 tonne and 2.75 m respectively. 80 tonne of machinery are put on board and in order to maintain stability 54 tonne of Ballast are at Kg 0.15m.  The final GM is 0.13 m. Calculate the Kg of the added machinery.

Q7. A) Why is an inclining experiment carried out? Write short account of the method adopted.

b) An inclining experiment was carried out on a ship of 8000 tonne displacement. The inclining ballast was moved transversely through 12 m and the deflections of a pendulum 5.5m long, measured from the centreline, were as follows

3 tonne port to starboard 64 mm S

3 Tonne 116 mm S

Ballast restored 3 mm S

3 Tonne starboard to port 54 mm P

3 tonne starboard to port 113 mm P

Calculate the metacentric height of the vessel. (10)

Q8. A. Explain the purpose of non-watertight longitudinal subdivision of tanks.

B. A ship 160m long and 8700-tonne displacement floats at a waterline with ½ ordinates of 0, 2.4, 5.0, 7.3, 7.9, 8.0, 8.0, 7.7, 5.5, 2.8, 0m respectively. While floating at this waterline, the ship develops a list of 10° due to instability. Calculate the negative metacentric height when the vessel is upright in this condition.