Description : What is the effect on speed if the load is increased on a 3 phase synchronous motor?
Last Answer : The speed of operation remains constant from no load to maximum load in the motor operating at constant frequency bus bars.
Description : A synchronous motor is operating on no-load at unity power factor. If the field current is increased, power factor will become (A) Leading & current will decrease (B) Lagging & current will increase. (C) Lagging & current will decrease. (D) Leading & current will increase.
Last Answer : Ans: A Initially synchronous motor is operating at no load and unity power factor. When field current increases, the excitation will increase. Therefore, p.f will be leading and current will be I CosΦ < I
Description : The effect of carrying field excitation excessively high on a synchronous motor will result in a _____________. A. tendency for the motor to fall out of step B. tendency for the motor to overspeed C. tendency for the motor to overheat D. loss of motor speed regulation
Last Answer : Answer: C
Description : If the input-signal-developing impedance of an amplifier is increased, what is the effect on the gain?
Last Answer : The gain increases.
Description : How may the tr tube ionization speed be increased?
Last Answer : Apply keep-alive voltage.
Description : How were processing speed and reliability increased in second generation computers?
Last Answer : By the use of small, long lasting transistors.
Description : What determines the number of field poles required to establish a rotating magnetic field in a multiphase motor stator?
Last Answer : The number of phases in the applied voltage.
Description : What is the effect of motor reaction in a dc generator?
Last Answer : A force which causes opposition to applied turning force.
Description : Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by ____________. ... an electric welder and feeding it into the armature while running the motor at full speed
Last Answer : Answer: A
Description : Which of the following statements is true concerning the operating characteristics of a squirrel-cage motor? A. Rotor slip is dependent upon the motor load. B. An increase in motor load results in ... results in less generated current. D. A decrease in rotor speed produces a weaker magnetic field.
Description : The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM
Last Answer : Answer: B
Description : Regarding an induction motor, the power developed by the rotor automatically adjusts itself to the _____________. A. power required to drive the load B. speed required to drive the load C. current flow in the motor stator D. torque developed by the rotating field
Description : In Induction motor Slip frequency of rotor current, when rotor speed is Nr. Then rotor producing slip field rotates with respect to stator is a) Slip frequency b) Nr c) Ns d) None
Last Answer : Ans: Ns
Description : A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will a) Both increases b) Both decreases c) Increases and decreases d) Decreases and increases
Last Answer : Ans: Both increases
Description : A salient pole synchronous motor is running at no load. Its field current is switched off. The motor will (A) come to stop. (B) continue to run at synchronous speed. (C) continue to run at ... more than the synchronous speed. (D) continue to run at a speed slightly less than the synchronous speed.
Last Answer : (B) continue to run at synchronous speed.
Description : If field current is decreased in shunt dc motor, the speed of the motor (a) remains same. (b) increases. (c) decreases. (d) none of the above.
Last Answer : increases
Description : If the current was increased to 4 amps, what would be the voltage drop across each resistor in the circuit described in question 17?
Last Answer : E1 = 80 volts. E2 = 240 volts. E3 = 320 volts
Description : What type of temperature coefficient material does not produce increased heat in response to increased current flow?
Last Answer : Zero-temperature coefficient.
Description : What is the effect on magnetron operation if the magnetic field strength is too high?
Last Answer : The magnetron will not oscillate.
Description : What will be the effect upon an electron traveling in the opposite direction to the lines of force in an electrostatic field?
Last Answer : The electron will be accelerated.
Description : If the constant-speed electrons in a reflex klystron remain in the repeller field for 1 3/4 cycles, what is the mode of operation?
Last Answer : Mode 2.
Description : The constant-speed electrons of an electron bunch in a reflex klystron must remain in the repeller field for what minimum time?
Last Answer : Three-quarter cycle.
Description : The speed of the rotor is always somewhat less than the speed of the rotating field. What is the difference called?
Last Answer : Slip.
Description : What is the effect of increased load on power factor of induction motor?
Last Answer : Power factor of an induction motor increases with loading.
Description : If the polar moment of inertia is increased to four times, then what will be the effect on free torsional vibrations of a single motor system? A. Increases 4 times B. Increases 2 times C. Decreases 4 times D. Decreases 2 times
Last Answer : B. Increases 2 times
Description : If the mass moment of inertia is increased to four times, then what will be the effect on free torsional vibrations of a single motor system? a) Increases 4 times b) Increases 2 times c) Decreases 4 times d) Decreases 2 times
Last Answer : d) Decreases 2 times
Description : If the polar moment of inertia is increased to four times, then what will be the effect on free torsional vibrations of a single motor system? a) Increases 4 times b) Increases 2 times c) Decreases 4 times d) Decreases 2 times
Last Answer : b) Increases 2 times
Description : Trade-offs between competing effects are necessary for high speed response. Which competing effect (fast transit time, low capacitance, or high quantum efficiency) requires a thin active area?
Last Answer : Fast transit time.
Description : Why speed of the induction motor falls when load is increased?
Last Answer : As the load increases, the speed reduces to deliver theincreased torque required.
Description : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to?
Last Answer : If load on a d.c. shunt motor is increased, its speed is decreased due primarily to decrease in back e.m.f.
Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.
Last Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.
Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.
Last Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.
Description : If the amount of current in the conductor changes, what happens to the magnetic field around the conductor?
Last Answer : If the current increases the magnetic field increases; if the current decreases the magnetic field decreases.
Description : What effect does an increase in capacitance have on a capacitor’s opposition to current flow?
Last Answer : Opposition to current flow decreases.
Description : What effect does the shielding of the screen grid by the control grid have on plate current in beam-forming tetrodes?
Last Answer : By increasing the number of electrons that reach the plate, plate current is increased.
Description : During avalanche effect breakdown, what limits current flow through the diode?
Last Answer : an external current-limiting resistor
Description : What effect does an inductor have on a change in current?
Last Answer : An inductor opposes a change in current.
Description : What effect does inductance have (a) on steady direct current and (b) on direct current while it is changing in amplitude?
Last Answer : a) No effect. (b) Inductance opposes any change in the amplitude of current.
Description : What is the effect on total resistance and total current in a circuit if a short occurs in (a) a parallel branch, and (b) in a series portion?
Last Answer : (a) Total resistance decreases, total current increases (b) Total resistance decreases, total current increases
Description : What is the effect on total resistance and total current in a circuit if an open occurs in (a) a parallel branch, and (b) in a series portion?
Last Answer : (a) Total resistance increases, total current decreases (b) Total resistance becomes infinite, total current is equal to zero
Description : What is the effect of current flow through the coil in a d’Arsonval meter movement?
Last Answer : A magnetic field is generated around the coil and the attraction of this field with the permanent magnet causes the coil to move
Description : Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. ... slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.
Description : Damp armature windings in a D.C. motor may lead to ____________. A. reduced voltage B. reduced current C. increased resistance D. overheating
Last Answer : Answer: D
Description : The air gap provided in induction motors should be checked periodically with a feeler gage to detect an unequal air gap and _____________. A. decreased motor magnetizing current B. hysteresis loses C. increased power factor D. mechanical damage to the rotor
Description : Neglecting saturation, if current taken by a series motor is increased from 10 A to 12 A, the percentage increase in its torque is ........ percent
Last Answer : Neglecting saturation, if current taken by a series motor is increased from 10 A to 12 A, the percentage increase in its torque is 44 percent
Description : What is the effect on the magnitude of emf generated in an AC generator if the speed of rotation is increased?
Last Answer : The magnitude of emf generated increases.
Description : The induced current can be increased by: a. Using strong magnetic field b. moving loop faster c. Replacing loop by coil d. all of above
Last Answer : d. all of above