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This set of Electromagnetic Interference Multiple Choice Questions & Answers (MCQs) focuses on Electromagnetic Interference Set 4
Q1 | In an electro dynamometer type of wattmeter
- the current coil is made fixed
- the pressure coil is fixed
- any of the two coils current coil or pressure coil can be made fixed.
- both the coils should be movable.
Q2 | In electro dynamometer type of wattmeter current coils designed for carryingheavy currents use stranded wires or laminated conductors :
- to reduce iron losses
- to reduce hysteresis losses
- to reduce eddy current losses in the conductors
- all of the above.
Q3 | In an electro dynamometer type of wattmeter , the inductance of the pressurecoil circuit produces error :
- which is constant irrespective of the power factor of the load
- which is higher at low power factors
- which is lower at low power factors
- none of the above.
Q4 | The power in 3ph 4 wire circuit can be measured by using:
- five watt meters
- four watt meters
- three watt meters
- 1 watt meter.
Q5 | The resistance in the circuit of the moving coil of a dynamometer wattmetershould be
- almost zero
- low
- high
- none of the above
Q6 | A dynamometer wattmeter can be used for
- both d.c. and a.c.
- d.c. only
- a.c. only
- any of the above
Q7 | The pressure coil of a wattmeter should be connected on the supply side ofthe current coil when
- load impedance is high
- load impedance is low
- supply voltage is low
- none of the above
Q8 | In a low power factor wattmeter the pressure coil is connected
- to the supply side of the current coil
- to the load side of the current coil
- in any of the two meters at connection
- none of the above
Q9 | In a low power factor wattmeter the compensating coil is connected
- in series with current coil
- in parallel with current coil
- in series with pressure coil
- in parallel with pressure coil
Q10 | In a dynamometer 3-phase power factor meter, the planes of the twomoving coils are at
- 0°
- 60°
- 90°
- 120°
Q11 | The power factor of a single phase load can be calculated if theinstruments available are
- one voltmeter and one ammeter
- one voltmeter, one ammetqr and one wattmeter
- one voltmeter, one ammeter and one energy meter
- any of the above
Q12 | The power of a n-phase circuit can be measured by using a minimum of
- (n - 1) wattmeter elements
- n wattmeter elements
- (n + 1) wattmeter elements
- 2n wattmeter elements
Q13 | A Dynamometer type wattmeter responds to the:
- average value of the active power
- average value of the reactive power
- peak value of the active power
- peak value of the reactive power
Q14 | The power measurement in a balanced 3-phase circuit can be done by:
- one wattmeter method
- two wattmeter method
- three wattmeter method
- any of the above method
Q15 | The braking torque provided by a permanent magnet in a single phase energymeter is proportional to the
- square of the flux of the permanent magnet
- speed of the meter
- distance of the permanent magnet from the centre of the revolving disc
- all of the above.
Q16 | Which of the following is integrating instruments?
- power factor meter
- energy meter
- voltmeter
- ammeter
Q17 | The phenomenon of creeping occurs in
- voltmeter
- ammeter
- wattmeter
- watt-hour meter
Q18 | Hole s are drilled on the opposite sides of the spindle of an energy meter toavoid
- balance of the disc
- dissipate heat generated due to eddy currents
- avoid creep on load
- increase the deflection torque
Q19 | The pressure coil of an induction type energy meter is
- highly inductive
- highly resistive
- purely inductive
- purely resistive
Q20 | Which type of damping is used in Induction type energy meter?
- air friction
- fluid friction
- gravity
- eddycurrent
Q21 | In an Induction type energy meter, maximum torque is obtained when theparameter of the rotating disc are
- r=0
- x=0
- r=x
- none of the above
Q22 | An Induction meter meter can handle current upto
- 10a
- 30a
- 200a
- 100a
Q23 | In an induction type energy meter, compensation for static friction isprovided by
- drilling holes in the disc
- lag circuits
- shading bands
- none of the above
Q24 | Which of the following statements is wrong
- there is control spring
- there is a brake magnet
- creeping error is present
- disc revolves continuously
Q25 | Which of the following is an essential part of a induction type of meter ?
- an operating torque system
- a braking device
- revolution registering device
- all of the above