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1) During load test on 3 phase induction motor, the readings of the two wattmeters are -5.5 kW and +12.5 kW respectively. If the line voltage is 420 V then the line current will be a. 38.91 A b. 41.02 A c. 42.10 A d. 43.94 A
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2) The two wattmeters used for the measurement of power input read 50 kW each. What will be the readings of the two wattmeter if the power factor is changed to 0.8 leading keeping the total input power same? a. 28.35W, 71.65W b. 31.25W, 73.71W c. 33.33W, 73.33W d. 38.35W, 75.5W
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3) Ballistic galvanometer are principally used for the measurement of a. Current b. Voltage c. Power d. Electric charges
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4) Vibration galvanometer are generally used a. For measuring electric charges b. As null-point detectors in ac bridges c. As null-point detectors in dc bridges d. For measuring power
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5) The meter of a vibrating reed frequency meter depends for its indications on the a. Electrical resonance of thin flat steel reeds b. Mechanical resonance of thin flat steel reeds c. Mechanical resonance of thick flat steel reeds d. Electrical resonance of thick flat steel reeds
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6) The electrodynamic frequency meters have a. Linear scale and their readings does not depends on voltage b. Linear scale and their readings depends on voltage c. Non linear scale and their readings does not depends on voltage d. Non linear scale and their readings depends on voltage
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7) A moving iron frequency meter consists of a. Two inductive circuits connected in parallel b. One inductive and one non inductive circuit connected in parallel c. Two non inductive circuits connected in parallel d. One inductive and one non inductive circuit connected in series
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8) If the frequency of electrodynamic power factor meter is doubled then its reading will become a. Twice of the original reading b. Half of the original reading c. Four times of the original reading d. Remains unaffected
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9) Moving iron power factor meter are suitable for 3 phase balanced circuits. It consists of a. One control spring b. Two control spring c. Three control spring d. No control spring
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10) In Nalder-Lipman moving iron power factor meter, the magnetic field produced a. Rotates in clockwise direction b. Rotates in anticlockwise direction c. Rotates in both clockwise and anticlockwise direction alternately d. No rotating magnetic field is produced
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11) A series reactance coil is used in Weston frequency meter. This coil is used to a. Suppress harmonics present in the current flowing through the meter b. Minimizes the waveform errors c. Both (a) and (b) d. None of these
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12) The coils of rotating type phase sequence indicator are mounted at a. 60 degree apart in space b. 90 degree apart in space c. 120 degree apart in space d. 180 degree apart in space
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13) The instrument which works only with dc is a. Electrolytic motor b. Mercury motor c. Induction motor d. Both (a) and (b)
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14) The electrolytic energy meters are essentially a. A true watt-hour meter b. An ampere hour meter c. Either watt-hour or ampere hour meter d. Neither watt-hour nor ampere hour meter
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15) An electrolytic ampere hour meter can be converted into watt-hour meter by a. Multiplying them by the voltage of the circuits in which it is used b. Multiplying them by the current of the circuits in which it is used c. Multiplying them by the power of the circuits in which it is used d. Cannot be converted
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16) Commutator type meters can be used for a. AC supply b. DC supply c. Both AC and DC supply d. None of these
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17) In case of motor meters, the speed of rotation is a. Directly proportional to the current in case of ampere hour meter and to power in case of watt-hour meter b. Directly proportional to the current in case of ampere hour meter and inversely proportional to the power in case of watt-hour meter c. Inversely proportional to the current in case of ampere hour meter and directly proportional to the power in case of watt-hour meter d. Inversely proportional to the current in case of ampere hour meter and to power in case of watt-hour meter
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18) In motor meters, the speed control of the rotating system is done by using a. Permanent magnet b. Train of gear wheels and dials c. Pinion d. All of these
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19) Commutator motor meters are a. Ampere hour meter b. True watt-hour meter c. Either ampere hour meter or true watt-hour meter d. None of these
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20) The induction type single-phase watt-hour meters uses a. Control spring b. Pointer c. Brake magnet and spindle d. All of these
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