If stator field is rotating in clockwise direction rotor rotates in clockwise
Description : The rotor of a synchronous motor operates in synchronism with the rotating field because ______________. A. of the amortisseur windings B. the rotor is magnetically locked into step with the ... field strength varies directly with rotor slip D. the stator flux rotates in the opposite direction
Last Answer : Answer: B
Description : A synchronous motor maintains synchronism with the rotating field because _____________. A. field strength varies directly with rotor slip B. DC current applied to the rotor coils causes the rotor ... the flux created by the excitation current D. the stator flux rotates in the opposite direction
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 : An electric motor in which both stator field and rotor rotates with same speed is called?
Last Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.
Description : In a three-phase, squirrel-cage type, induction motor the rotating magnetic field is established by the _____________. A. current induced in the rotor windings B. application of a three-phase voltage ... caused by the induced current in the squirrel-cage bars with the magnetic field of the stator
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
Last Answer : Answer: A
Description : In an induction motor, rotor currents are circulated in the rotor by _____________. A. slip rings and brushes B. an armature and brushes C. inductive reaction of the rotating stator field D. external variable resistors
Last Answer : Answer: C
Description : A rotating electrical machine its self-inductances of both the stator and the rotor windings, independent of the rotor position will be definitely not develop (A) starting torque (B) synchronizing torque (C) hysteresis torque (D) reluctance torque
Last Answer : A rotating electrical machine its self-inductances of both the stator and the rotor windings, independent of the rotor position will be definitely not develop synchronizing torque
Description : What is the direction of rotation of rotor with respect to the rotating magnetic field?
Last Answer : Answer: Rotating Magnetic Field is set up when 3 phase ac supply is provided to the stator windings of the induction motor. Rotating Magnetic Field rotates at synchronous speed. Rotor rotates in the direction of the rotating magnetic field
Description : In the diagram shown below, if rotor X and rotor Z rotate in same direction and rotor Y rotates in opposite direction, then specify the type of node vibration. A. Three node vibration B. Two node vibration C. Single node vibration D. None of the above
Last Answer : B. Two node vibration
Description : In the diagram shown below, if rotor X and rotor Z rotate in same direction and rotor Y rotates in opposite direction, then specify the no of degree of freedom vibration.a. Three degree of freedom vibration b. Two degree of freedom vibration c. Single degree of freedom vibration d. None of the above
Last Answer : b. Two degree of freedom vibration
Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.
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 : Which of the following statements is/are true? A. Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction B. Shaft vibrates with maximum frequency when rotors ... C. Zero node behavior is observed in rotors rotating in opposite direction D. All of the above
Last Answer : A. Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction
Description : Which of the following statements is/are true? A) Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction B) Shaft vibrates with maximum frequency when rotors ... C) Zero node behavior is observed in rotors rotating in opposite direction D) All of the above
Last Answer : A) Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction
Description : Which of the following statements is/are true? a. Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction b. Shaft vibrates with maximum frequency when rotors ... c. Zero node behavior is observed in rotors rotating in opposite direction d. All of the above
Last Answer : a. Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction
Description : A DC generator is used to supply direct current in order to maintain an AC generator field and is known as a/an _____________. A. rotor B. stator C. exciter D. armature
Description : In the illustrated device, the part labeled '1A' _________. EL-0001 A. are start and run windings for a single phase shaded pole induction motor B. is the stator for a polyphase induction ... armature for a squirrel cage rotor motor D. are direct current shunt field windings for a universal motor
Description : For a DC motor, what major component in addition to the field winding and the armature winding is necessary? w) a commutator x) a stator y) a battery z) a rotor
Last Answer : ANSWER: W -- A COMMUTATOR
Description : in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure:
Last Answer : in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure: At synchronous speed in the direction of stator field
Description : If an AC generator experiences voltage failure, the cause may be _____________. A. an open in the field circuit B. the brushes shifting out of the neutral plane C. excessive locked-rotor current D. a rotating slip ring
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
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 : A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60
Last Answer : 0
Description : 1. Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop. -Physics-10
Last Answer : Solution: For the downward direction of the current, the direction of the magnetic field will be as if emerging from the table outside the loop and merging with the table inside the loop. Similarly, ... the table outside the loop and merging with the table inside the loop, as shown in the figure.
Description : If the driving torque, such as that produced by a diesel engine, creates pulsations when coupled with a synchronous generator operating in parallel; the generator rotor may be periodically pulled ahead or behind ... as it rotates. This co A. hunting B. direct coupling C. peaking D. harmonic coupling
Description : If the driving torque, such as that produced by a diesel engine, creates pulsations when coupled with a synchronous generator operating in parallel; the generator rotor may be periodically pulled ... windings B. direct coupling C. increase governor speed droop D. decreasing governor speed droop
Description : If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of 400 rps. The frequency of the induced output voltage will be: A. 40 Hz B. 100 Hz C. 400 Hz D. indeterminable
Last Answer : If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of 400 rps. The frequency of the induced output voltage will be: 400 Hz
Description : Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C
Last Answer : Ans: A
Description : As shown in the illustration, the purpose of the item labeled 'Z', in assembly No. 2, is to _____________. EL-0001 A. keep the rotor in balance B. align the rotor to the stator C. dynamically balance the rotor D. cool the motor
Last Answer : Answer: D
Description : The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.
Description : On large generators, space heaters are used to ____________. A. keep the machine at ambient tmperature of the machinery space B. maintain rotor and stator winding temperatures above the dew point ... C. prevent condensation in the lube oil D. prevent electrolysis due to condensation in the bearings
Description : The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit
Description : Air gap readings for electrical generating equipment should be taken periodicly. This is to _______. I. determine the condition of the bearings II. prevent damage to the rotor and stator A. I only B. II only C. both I and II D. neither I or II
Description : The purpose of the item labeled 'Z' in assembly No. 2, shown in the illustration is to _____________. EL-0001 A. keep the rotor in balance B. align the rotor to the stator C. dynamically balance the rotor D. cool the motor
Description : In the illustrated motor, roller bearings are used because __________. EL-0001 A. of their ability to absorb moderate thrust loads B. they electrically insulate the rotor from the frame reducing ... clearance between the rotor and stator is generally as close as mechanical tolerance will permit
Description : The air gap in an induction motor should be periodically checked with a feeler gage to prevent possible ___________. A. rotor contact with the stator B. axial misalignment of the rotor C. damage to the motor bearings D. electrical damage to the bearings
Description : The speed of a multi-speed, squirrel-cage, induction motor operating in a fixed frequency system can be changed by _____________. A. reconnecting stator windings for different numbers of poles B. ... sequence of the applied voltage D. reconnecting the stator so that no poles have the same polarity
Description : The speed of a squirrel-cage induction motor is determined by the ____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. rotor conducting bars resistance
Description : The speed of a three-phase squirrel-cage induction-type motor operating in a fixed frequency system is varied by changing the _____________. A. number of phases to the motor B. number of stator poles C. locked rotor current D. resistance of the rotor winding
Description : The speed of a squirrel cage induction motor is determined by the _____________. A. diameter of the stator B. number of stator poles C. rotor winding resistance D. bar resistance of the conducting rotor
Description : The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor
Description : Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor
Description : A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit
Description : The torque produced by a motor when its shaft will not turn, even though rated voltage is applied to the stator, is known as _____________. A. locked-rotor torque B. pullout torque C. breakdown torque D. torque margin
Description : What is the relative speed between the fields set up by the stator and rotor?
Last Answer : Answer: Stationary. The speed of the stator field with respect to stator surface will be Ns and the speed of rotor with respect to the stator surface will be N. The speed of the magnetic field ... x Ns= Ns Therefore the relative motion between stator field and rotor field will be stationary or zero.
Description : What Is Meant By Stator? What Is Meant By Rotor?
Last Answer : In any electrical machine ( AC/DC motor or generator) the stationary member is called as stator. Similarly in all machines the rotating member is known as rotor.
Description : List the undesirable effects produced by certain combination of rotor and stator slots.
Last Answer : 1. The motor may refuse to start (cogging) 2. The motor may run at sub synchronous speed (Crawling) 3. Severe vibrations may develop and the noise will be excessive.
Description : What is rotor and stator resistance values?
Last Answer : Rotor resistance = 98.1 m Stator winding resistance’s R φ = 3.1 /3.1 Y φ = 3.1 /3.1 B φ = 3.1 /3.1