Top 150+ Solved Electromagnetic Interference MCQ Questions Answer
Q. In an electro dynamometer type of wattmeter
a. the current coil is made fixed
b. the pressure coil is fixed
c. any of the two coils current coil or pressure coil can be made fixed.
d. both the coils should be movable.
Q. In electro dynamometer type of wattmeter current coils designed for carryingheavy currents use stranded wires or laminated conductors :
a. to reduce iron losses
b. to reduce hysteresis losses
c. to reduce eddy current losses in the conductors
d. all of the above.
Q. In an electro dynamometer type of wattmeter , the inductance of the pressurecoil circuit produces error :
a. which is constant irrespective of the power factor of the load
b. which is higher at low power factors
c. which is lower at low power factors
d. none of the above.
Q. The power in 3ph 4 wire circuit can be measured by using:
a. five watt meters
b. four watt meters
c. three watt meters
d. 1 watt meter.
Q. The resistance in the circuit of the moving coil of a dynamometer wattmetershould be
a. almost zero
b. low
c. high
d. none of the above
Q. A dynamometer wattmeter can be used for
a. both d.c. and c.
b. d.c. only
c. a. only
d. any of the above
Q. The pressure coil of a wattmeter should be connected on the supply side ofthe current coil when
a. load impedance is high
b. load impedance is low
c. supply voltage is low
d. none of the above
Q. In a low power factor wattmeter the pressure coil is connected
a. to the supply side of the current coil
b. to the load side of the current coil
c. in any of the two meters at connection
d. none of the above
Q. In a low power factor wattmeter the compensating coil is connected
a. in series with current coil
b. in parallel with current coil
c. in series with pressure coil
d. in parallel with pressure coil
Q. In a dynamometer 3-phase power factor meter, the planes of the twomoving coils are at
a. 0°
b. 60°
c. 90°
d. 120°
Q. The power factor of a single phase load can be calculated if theinstruments available are
a. one voltmeter and one ammeter
b. one voltmeter, one ammetqr and one wattmeter
c. one voltmeter, one ammeter and one energy meter
d. any of the above
Q. The power of a n-phase circuit can be measured by using a minimum of
a. (n - 1) wattmeter elements
b. n wattmeter elements
c. (n + 1) wattmeter elements
d. 2n wattmeter elements
Q. A Dynamometer type wattmeter responds to the:
a. average value of the active power
b. average value of the reactive power
c. peak value of the active power
d. peak value of the reactive power
Q. The power measurement in a balanced 3-phase circuit can be done by:
a. one wattmeter method
b. two wattmeter method
c. three wattmeter method
d. any of the above method
Q. The braking torque provided by a permanent magnet in a single phase energymeter is proportional to the
a. square of the flux of the permanent magnet
b. speed of the meter
c. distance of the permanent magnet from the centre of the revolving disc
d. all of the above.