1. Sketch and describe a main engine shaft driven generator arrangement with an electronic system for frequency correction. (16)
ANSWER CLICK2. State the applications of the synchronous motors. Discuss how a synchronous motor can function as a synchronous capacitor. Compare synchronous motors with induction motor drives.
3.a) Explain three methods of overcurrent protection for electrical circuit.
b) Explain with aid of diagram, the meaning of the term inverse current time characteristic.
ANSWER CLICK
4. With respect to Alternators onboard:
a) Briefly explain True Power, Apparent Power and Power Factor?
b) The alternator is rated for 750 KVA at 0.85 PF. What is the maximum load (Kilo Watt) that can be put on it? Would you be overloading the alternator if the Kilowatt reading were now 620 KW and the power factor 0.80?
5. Explain with the help of a neat diagram the operation of a Brushless alternator. What would likely happen if one of the rotating Diodes fails and becomes:
(a) An open circuit?
(b) A Short Circuit?
6. With Reference to 3-phase Transformers:
a) Discuss the essential and desirable 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? (5)
c)In a 25kW, 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.
. With Refererice to Maritime Labour Convention (MLC) answer the following. -
ANSWER CLICK
7a) Explain the structure of the convention with titles.
b) Briefly, discuss DMLC Part I and Part II covering welfare measures for seafarers.
ANSWER CLICK
8. Explain how PSC is different from FSC? Discuss Clear Grounds under SOLAS, MARPOL and the STCW with examples.
9. Discuss the following with respect to International Safety Management (ISM) Code:
a) Emergency preparedness, drills & training.
b) Reporting of near miss, non-conformities, accidents/incidents, and hazardous occurrences.
c)Risk assessment Identification of critical equipment, tests, and minimum spares requirement.
FEB – 2025
1. a) State essential electrical services on board that are
able to be operable under fire conditions.
b) Explain how electric cables for the essential services in
part (a) pass
through bulkheads whilst maintaining gas tight and watertight
integrity.
c) State the requirements for the cables which supply
electrically driven
emergency fire pumps
2.a) Sketch a circuit diagram of a push button direct online
contactor starter for a three phase Incorporating overload and short circuit
protection
b) Indicate, on a sketch of the typical characteristic curves
of current and
torque against Speed, disadvantages of a direct online start
squirrel cage induction motor.
3. Differentiate between half and full wave rectification.
State where half
wave rectification may be used and the purpose for which it is
not weli
adapted. Sketch a bridge connection by which full wave rectification may be obtained..
SECTION II
4.a) Explain the potential hazards if liquid-cooled
transformers are used.
b) What are the losses in transformers? Mention the various
factors which affect these losses. C) in a 25 KVA, 3300/233 V, single phase
transformer, the iron and full-load Cu. losses are respectively 350 and 400
watts. Calculate the efficiency at half-full load, 0.8 power factor.
5.a) List the factors that determine the starting torque of
the three phase induction motor How does this torque generally compare with the
value of the rated torque?
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 ohm. When connected to a 220 V, 50 Hz, a.c.
supply the current taken is at first 2 A, and when the plunger is drawn into
the "full-in" position the current falls to 0.7 A. 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.
6.a) With the aid of delta and star connection diagrams, state
the basic
equation from which the delta-star and star-delta conversion
equation can be derived.
b) Three batteries A, B, and C have their negetive terminals
connected
together. Between the positive terminals of A and B there is a
resistor of 0.5 ohm and between B and C there is a resistor of 0.3 ohm. Specifications
of the three batteries are given below.
Battery A 105 V, Internal resistance 0.25 ohm
Battery B 100 V, ,, ,, ,, 0.2 ohm
Battery C 95 V, ,, ,, ,, 0.25 ohm
Determine the current values in the two resistors and the
power dissipated by them.
7. With respect to MARPOL 73/78, Annex II, Noxious liquid
chemicals are divided into categories;
a). State the number of categories, and what does each
category signify.
b) State the requirement of Procedures and Arrangements
Manual, and what information is available.
8. With reference to free fall lifeboat of an ocean-going
ships:
a) Periodical maintenance, tests and checks on lifeboat and
releasing gear.
b) Secondary means of lowering.
c) Lifeboat Drills.
9. Briefly discuss the following with respect to safety of
navigation:
a) Bridge Navigation Watchkeeping Alarm System (BNWAS)
b) Long Range Identification and Tracking of ships (LRIT)
c) Voyage Simplified Voyage Recorder (VDR/S-VDR)
MARCH – 2025
SECTION-I
1. a) What precautions must be taken when testing the
insulation of
generator cables and wiring connected to an AVR unit?
b) How could you monitor the correct instant for
synchronising, if
synchroscope and synchronising lamps are not working?
c) How is the air gap of an alternator measured and why the
air gap of an
alternator to be checked periodically?
2. a) Explain with the aid of a diagram, a controller
utilizing proportional plus integral action.
b) List out the Advantages and Disadvantages of electric
propulsion system
c) Explain briefly what you know about "Pulse Width
Modulation" and how it can be applied for propulsion control.
3. With Respect to PLC's used onboard ships:
a) Draw and explain the block diagram of a PLC.
b) Name the onboard ship equipment where PLC's are used.
c) What are the advantages of PLC controllers over other type
of controllers?
SECTION II
4.a) What design factor limits the maximum torque of a d-c
motor?
b) A shunt motor runs on no load at 700 r/min off a 440 V
supply. The
resistance of the shunt circuit is 24012. The following table
gives the
relationship between the flux and the shunt current:
Shunt current (A) 0.5 0.75 1.0 1.25 1.5 1.75 2.0
Flux per pole (mWb) 6.0 8.0 9.4 10.2 10.5 11.2 11.5
Calculate the additional resistance required in the shunt
circuit to raise the no-load speed to 1000 r/min
2024/NOV/04 2023/JAN/04 2025/MAR/04
5. a) On what factors does the capacitance of a parallel -
plate capacitor
depend?
b) A tuned circuit consisting of a coil having an inductance
of 200μ H and a resistance of 20Ω in parallel with a variable capacitor is
connected in series with a resistor of 8000Ω across a 60 V supply having a
frequency of 1 MHz. Calculate:
a) The value of C to give resonance.
b) The dynamic impedance and the Q factor of the tuned
circuit.
c) The current in each branch.
6.a) The capacitor - start induction run motor has a much
higher starting torque than the resistance split-phase motor. Explain.
b) An 8-pole armature is wound with 480 conductors. The
magnetic flux and the speed are such that the average e.m.f. generated in each
conductor is 2.2 V, and each conductor is capable of carrying a full load
current of 100 A.
Calculate the terminal voltage on no load, the output current
on full load and the total power generated on full load when the armature is
(i) lap connected.
(ii) Wave connected
SECTION-III
7. With reference to port State control
a) List the certificates and documents which a Port State
Control Officer
(PSCO) may like to see during inspection.
b) List the Life Saving Appliances and Fire Fighting Equipment
which are
likely to be inspected by PSCO.
8. Explain the following with respect to MARPOL Annex-l
a) Pump room bottom protection.
b) Intact stability of oil tankers.
c) Subdivision and damage stability of oil tankers.
9. With reference to MLC answer the following
a) Briefly discuss DMLC Part I and Part II covering the
welfare points for
seafarers.
b) Briefly discuss the grievance redressal mechanism for
seafarers of Indian flagged vessel.
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