Q1:- A series inductor is normally added in a thyrister circuit for achieving protection against:
(1) High current
(2) High voltage
(3) High di/dt
(4) High dv/dt
ANSWER:-3
Q2:-Clamp on ammeter is used for measurement of:
(1) Large alternating currents
(2) Small direct currents
(3) Small alternating currents
(4) Large direct currents
ANSWER:-1
Q3:- Consider the following statements Over head transmission lines are provided with earth wires:
1. To protect the transmission line from direct lightning strike
2. To protect the transmission line insulation from the indirect lightning strike
3. To balance the line currents
4. To provide path for neutral current
Which of these statement/s is/are correct?
(1) 1 and 3
(2) 1 and 4
(3) 1 only
(4) 2 only
ANSWER:-3
Q4:- An ammeter has a current range of 0–5 A, and its internal resistance is 0.2Ω. In order to change the range to 0–25 A, what should be the value of resistance added and how it would connect with meter (i.e. series/parallel)?
(1) (0.05Ω/series)
(2) (0.05Ω /parallel)
(3) (0.20Ω/parallel)
(4) (0.20Ω/series)
ANSWER:-2
Q5:- Power consumed by a balanced 3-phase, 3-wire load is measured by two wattmeter method. The first wattmeter reads twice that of the second. Then what will be the load impedance angle in radian?
(1) (π/6)
(2) (π/3)
(3) (π/2)
(4) (π/4)
ANSWER:-1
Q6:-The X/R ratio for distribution lines is:
(1) Less than unity
(2) More than unity
(3) Equal to unity
(4) None of these is necessary
ANSWER:-2
Q7:- Corona loss is minimum in:
(1) Monopolar HVDC line
(2) Bipolar HVDC line
(3) Both in Monopolar& Bipolar HVDC lines
(4) EHV AC lines
ANSWER:-1
Q8:-The potential transformers’ Nominal Ratio is defined as the ratio of:
(1) Primary winding voltage and secondary winding voltage
(2) Rated primary winding voltage and rated secondary winding voltage
(3) Primary winding turns and secondary winding turns
(4) Any of the above
ANSWER:-2
Q9:-Whenever a 3–phase fault takes place at the terminals of an induction generator, the sustained fault current is:
(1) Equal to the full load current
(2) About 20 times the full load current
(3) Much less than full load current
(4) About 10 times the full load current
ANSWER:-3
Q10:-For complete protection of a 3– phase line:
(1) Three phase and three–earth fault relays are required
(2) Three phase and two–earth fault relays are required
(3) Two phase and two–earth fault relays are required
(4) Two phase and one–earth fault relays are required
ANSWER:-4
Q11:-When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their
(1) KVA rating are identical
(2) Efficiencies are equal
(3) P u impedance are equal
(4) Equivalent impedance are equal
ANSWER:-3
Q12:- The most efficient torque – producing actuating
structure for induction – type relay is:
(1) Shaded pole structure
(2) Watt – hour – meter structure
(3) Induction – cup structure
(4) Single – induction loop structure
ANSWER:-3
Q13:-Triac are usually operated at:
(1) All frequencies
(2) High frequency only
(3) Power frequency
(4) None of these
ANSWER:-3
Q14:- Earth wire on EHV overhead transmission line is provided to protect the line against:
(1) Lightning surge
(2) Switching surge
(3) Excessive fault voltage
(4) Corona effect
ANSWER:-1
Q15:- The measurement range of an ammeter can increased by using a
(1) High resistance in shunt
(2) Low resistance in shunt
(3) High resistance in series
(4) Low resistance in series
ANSWER:-2
Q16:- Three equal resistors, connected in series across a
source of emf, dissipated 10W of power. What would be
the power dissipated in the same resistor when they are connected in parallel across the same source?
(1) 10W
(2) 30W
(3) 90W
(4) 270W
ANSWER:-3
Q17:-If a 3-pahse, 400V, 50Hz, 4 pole induction motor is
running at a slip of 5% then the relative speed of rotor
field with respect to stator filed is:
(1) Zero
(2) 75 rpm
(3) 142.5 rpm
(4) 1500 rpm
ANSWER:-1
Q18:- A 3-phase induction motor is running at slip ‘s’. If its
two supply leads are interchanged, then the operating slip at that instant will be
(1) 2s
(2) (1-s)
(3) (2-s)
(4) Zero
ANSWER:-3
Q19:- In a 3-phase voltage source inverter used for speed control of induction motor, anti-parallel diodes are used across each switching device. The main purpose of diodes is to:
(1) Protect the switching devices against over voltage
(2) Provide path for freewheeling current
(3) Allow the motor to return energy during regeneration
(4) Help in switching off the devices
ANSWER:-3
Q20:- Skewing of rotor bars eliminate the:
(1) Effect of space harmonics
(2) Entire effect of crawling
(3) Magnetic noise
(4) Vibration due to unequal force developed on rotor
ANSWER:-1
