DieselShip's Online Content Library

Q6. a) State Ohm's Law. (3)

b) State the limitations of Ohm's Law. (3)

c) If the resistance of a circuit is increased to 3 times and the applied Voltage is halved, what will happen to the circuit current? (10)

Q3. a) Explain the working of a Megger with the aid of its internal circuit. (12)

b) What safety measures are taken while using a Megger? (4)

Q3. a) What is the purpose of preferential Tripping system on ship's electrical network? (6)

b) Explain the various stages of preferential trips with the loads connected to those stages. (10)

Q4. a) List the applications of CT and PT (Current and voltage Transformers). (6)

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

Q5. a) What is single phasing of a 3 ph induction motor? (6)

b) What are the causes of single phasing? (6)

c) Explain any method of protection against single phasing? (4)

Q7. a) What is the difference between EMF and PD of a battery. (6)

b) Calculate the value of I1 in the following circuit. (10)

Q7. a) What is self-induction? (6)

b) A coil of 800 turns is wound on a wooden former and a current of 5A is passed through it to produce a magnetic flux of 200 micro-webers. Calculate the average value of e.m.f. induced in the coil when the current is

i) switched off in 0.08 seconds

ii) reversed in 0.2 seconds. (10)

Q8. a) What are the routine maintenance carried out on lead acid batteries? (6)

b) When a 10 Ω resistor is connected across a battery, the current is measured to be 0.18 A. If similarly tested with a 25 Ω resistor, the current is measured to be 0.08A. Find the e.m.f. of the battery and its internal resistance. Neglect the resistance of the ammeter used to measure the current. (10)

Q9. a) Name the various types of capacitors? (6)

b) A 500W, 100V bulb is to be connected across 250V, 50Hz mains. Find the value of the capacitor required to be connected in series. (10)

Q1. (a) With the aid of a circuit diagram explain the working of Bridge rectifier. (8)

(b) Compare the performance of Bridge rectifier with Full wave and Half wave rectifier. (8)

Q2. Explain with the aid of simple circuit diagram the grounded power distribution system and isolated power distribution system. (16)

Q3. a) What are non-linear resistors? (4)

b) Give three examples of non-linear resistors with their characteristics. (8)

c) Give examples of application of non-linear resistors. (4)

Q4. (a) Name at least three types of temperature sensing devices for remote indication. (4)

(b) Explain the working of a Thermocouple type temperature sensor. (8)

(c) What are various materials used in a thermocouple? (4)

Q5. a) What are the hazards associated with batteries? (6)

b) What safety precautions are to be taken while operating and maintaining the batteries including in battery room. (10)

Q6. (a) How does a moving coil ammeter measure large current (6)

(b) A moving coil instrument with a coil resistance of 1.98Ω, produces full scale deflection from a current of 10mA. Determine the value of shunt required to extend the range up to 10A. (10)

Q7. a) What is Kirchoff’s current Law. (6)

b) Calculate the value of I2 in the circuit, when I1= 3A. (10)

Q7. (a) Explain power factor with A.C. Sine wave and phasor diagram. (6)

(b) A circuit has a resistance value of 25Ω and an inductance value of 0.3H. If it is connected to a 230V, 50Hz supply, find the circuit current, the power factor and the power dissipation. (10)

Q8. (a) Compare Direct current with Alternating current. (6)

(b) A four-pole generator has a flux of 12 mWb/pole. Calculate the value of e.m.f. generated in one of the armature conductors, if the armature is driven at 900 rev/min. (10)