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Q4. A) Calculate the Line and Phase current at full load of a 50 kW, 440 Volt 3 phase deltas connected motor having full load efficiency 90% and power factor O.8 lagging. B) Calculate the starting current if motor is started by star/delta starter and Auto transformer starter which has transformer tapping 65 %

Q8. A. What is Silicon controlled rectifier (SCR)? How is the breakover voltage of the SCR defined? (6)

B. A d.c. motor takes an armature current of 110 A at 480 V. The resistance of the armature circuit is 0.2𝛀. The machine has six poles and the armature is lap-connected with 864 conductors. The flux per pole is 0.05 Wb. Calculate: (a) The speed; (b) The gross torque developed by the armature. (10)

Q7. An oil tanker 160m long and 22m beam floats at a draught of 9m in seawater. C_w is 0.865. The midships section is in the form of a rectangle with 1.2m radius at the bilges. A midships tank 10.5m long has twin longitudinal bulkheads and contains oil of 1.4 m³/t to a depth of 11.5m. The tank is holed to the sea for the whole of its transverse section.  Find the new draught.

Q10. A. List the precautions necessary before an inclining experiment is carried out.

B. A box shaped vessel, 50 metres long × 10 metres wide, floats in salt water on an even keel at a draft of 4 metres. A centre line longitudinal watertight bulkhead extends from end to end and for the full depth of the vessel. A compartment amidships on the starboard side is 15 metres long and contains cargo with permeability 30%. Calculate the list if this compartment is bilged. KG = 3 metres.

Q10. The daily fuel consumption of a ship at 17 knots is 42 tonne. Calculate the speed of the ship if the consumption is reduced to 28 tonne per day, and the specific consumption at the reduced speed is 18% more than at 17 knots.

Q10. A. Explain the use of KN curves. B. A ship of 6000 tonnes displacement has drafts 7m. f and 8m. A. MCT 1cm. 100 tonnes-m. TPC 20 tonnes, centre of flotation is amidships. 500 tonne of cargo is discharged from each of the following four holds.

No.1 hold, center of gravity 40m forward of amidships

No.2 hold, center of gravity 25m forward of amidships

No.3 hold, center of gravity 20m forward of amidships

No.4 hold, center of gravity 50m forward of amidships

The following bunkers are also loaded:  150 tonnes at 12m forward of amidships 50 tonnes at 15m aft of amidships Find the new drafts forward and aft.

Q4. (a) List the components of residuary resistance. (b) A ship model 6m long has a total resistance of 40N when towed at 3.6 knots in fresh water. the ship itself is 180m long and displaces 20400 tonne. the wetted surface area may be calculated from the formula S= 2.57, Calculate ePn for the ship at its corresponding speed in sea water. f (model)fw =0.492; f (ship)sw =0.421; n=1.825.

Q6. (a) Describe the movement of a ship with negative metacentric height. (b) A ship of 8000 tonne displacement has its centre of gravity 4.5m above the keel and transverse metacenter 5m above the keel when a rectangular tank 7.5m long and 15m wide contains seawater. A mass of 10 tonne is moved 12m across the deck. Calculate the angle of heel:(10) (i) If there is no free surface of water. (ii) if the water does not completely fill the tank.

Q9. A. Describe briefly the inclining experiment and explain how the results are used. B. A ship of 8500 tonne displacement has a double bottom tank 11m wide extending for the full breadth of the ship, having a free surface of seawater. If the apparent loss in metacentric height due to slack water is 14cm, find the length of the tank.

Q6. a) Derive the expression for current and voltage relations between line and phase values in the star and delta cases. Draw vector diagram.

b) Three impedances Z=5+j4 are connected in the form of a delta to the three loads of a balanced 3-phase circuit. The line voltage is 120 Volts.

Find (a) The phase current, (b) Power factor, (c) The volt-ampere in the circuit.

10.A box-shaped barge of uniform construction is 80 m long, 12 m beam and has a light displacement of 888 tonne. The barge is loaded to a draught of 7 m in sea water of density 1025 kg/ m? with cargo evenly distributed. over two end compartment of equal length. The empty midship compartment extending to the full width and depth of the barge is bilged and the draught increases to 10m.

Determine:

(a) the length of the midship compartment.

(b) the longitudinal still water bending moment at midships:

(i) in the loaded intact condition

(ii) in the new bilged condition

Q10. A. Describe the relationship between frictional resistance and: (i)Ship speed; (ii) the wetted area; (iii) surface roughness; (iv) The length of the vessel.  B.A ship travels at 15 knots and has a QPC of 0.865 with a delivered power of 2600 KW. The apparent slip is 5% and the real ship is 28%Calculate the total resistance and the wake friction.