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
Last Answer : Answer: A
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 : 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 : 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 : 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
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 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 : 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 : If stator field is rotating in clockwise direction rotor rotates in (A) any direction (B) cannot predict (C) anticlockwise (D) clockwise
Last Answer : If stator field is rotating in clockwise direction rotor rotates in clockwise
Description : The rotating shaft or rotor vibrates with excessive lateral vibration at angular speed at which occurs is called as A) rotating speed B) critical speed C) vibrating speed D) None of the above
Last Answer : B) critical speed
Description : In a 3-phase synchronous motor (A) the speed of stator MMF is always more than that of rotor MMF. (B) the speed of stator MMF is always less than that of rotor MMF. (C) the speed of ... speed while that of rotor MMF is zero. (D) rotor and stator MMF are stationary with respect to each other.
Last Answer : Ans: D Because, Motor is magnetically locked into position with stator, the rotor poles are engaged with stator poles and both run synchronously in same direction Therefore, rotor & stator mmf are stationary w.r.t each other.
Description : What is the main advantage of the rotating field alternator?
Last Answer : Output voltage is taken directly from the armature (not through brushes or slip rings).
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 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 : In a TDR system connected for addition in what direction will the TDR rotor field turn when the TX rotor to which it is connected turns counterclockwise?
Last Answer : Clockwise.
Description : Which gyro rotor in figure 3-6, view (A) view (B) view (C), will have the greatest rigidity if all are rotated at the same speed?
Last Answer : C.
Description : In an AC generator, direct current from a separate source is passed through the windings of the rotor _____________. A. by means of slip rings and brushes B. by means of a commutator C. by means of rotating bar magnet D. to minimize the danger of arc over
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 ____ pump consists of a reciprocating or rotating cavity between two lobes or gears and a rotor. a. positive c. negative b. centrifugal d. hand
Last Answer : a. positive
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 : A charged particle is rotating in uniform circular motion in a uniform magnetic field . Let r= radius of circule, v= speed of particle k = kinetic ene
Last Answer : A charged particle is rotating in uniform circular motion in a uniform magnetic field . Let r ... angular speed. then match the following two columns.
Description : The most practical way to control the voltage output of an AC generator is to vary the _____________. A. number of windings B. speed of the rotating field C. strength of the rotating magnetic field D. power factor of the load
Last Answer : The speed of the rotating magnetic field in an induction motor is known as the synchronous speed.
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 : Frequency of centrifugal pendulum absorber is always proportional to A) Oscillating motion B) Transfer motion C) Speed of rotating body D) All of the above
Last Answer : C) Speed of rotating body
Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field
Last Answer : Answer: D
Description : Under normal conditions, the speed of a two-speed squirrel cage induction motor is changed by varying the ____________. A. frequency of the applied voltage B. resistance in the rotor circuit C. number of field poles D. amplitude of the applied voltage
Description : The speed of a wound-rotor induction motor _____________. A. will be fixed by the number of field poles B. can be varied by a rheostat-type control C. can only be synchronous speed at full load D. can only attain synchronous speed at no load
Description : The purpose of a cage rotor winding placed on the rotor of a synchronous motor is to _____________. A. provide excitation to the DC field B. start the machine as an induction motor C. contribute extra torque at synchronous speed D. prevent the machine from falling out of step
Description : What is the speed of the rotor magnetic field with respect to rotor?
Last Answer : Answer: Currents flowing through the rotor windings due to induction caused by stator will have a frequency of ( f ', which is equal to sf where f is the applied frequency to stator). This current flowing through the rotor sets up a magnetic field equal to s x Ns with respect to the rotor.
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 : 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 : Rotating the plane of polarization of a wavefront by passing it through a ferrite device is called what?
Last Answer : . Faraday rotation.
Description : A specialty product is ________ intensively distributed than a shopping product A. More B. Less C. Somewhat more D. Substantially more
Last Answer : B. Less
Description : In developing a new herbicide, Atwell Chemicals comes up with two formulations. Option 1 is more effective in killing weeds but has a questionable impact on ground water. Option ... following moral philosophies? A)Egalitarianism B)Utilitarianism C)Ethical directionism D)Contract theory E)Pluralism
Last Answer : B)Utilitarianism
Description : No load current in a transformer: (A) lags the applied voltage by 90° (B) lags the applied voltage by somewhat less than 90° (C) leads the applied voltage by 90° (D) leads the applied voltage by somewhat less than 90°
Last Answer : Ans: B The primary input current under no load conditions has to supply (i) iron losses in the core i.e hysteresis loss and eddy current loss (ii) a very small amount of Cu loss in the primary (there being no Cu loss in secondary as it is open)
Description : Which of the two types of deflection coils (fixed or rotating) is used most often?
Last Answer : Fixed.
Description : What is the purpose of rotating the gimbal assembly in a gyro using a mercury erection system?
Last Answer : Applies torque at the proper point for correct precession.
Description : Why is no emf induced in a rotating coil when it passes through the neutral plane?
Last Answer : No flux lines are cut.
Description : Do you find that email and social networking has made you less likely to pick up a phone or go speak to someone in person, and phone calls and live interaction has become somewhat laborous?
Last Answer : answer:Personally, I'd prefer to talk on the phone. So many of my friends and relatives have gotten to accostumed to their iLives, that I find it impossible to find a good time to chat. Recently a ... tend to email things like: It'd be faster to converse this IRL. Call me at your convenience.
Description : If an ac voltmeter is connected between the S2 and S3 windings on a TX, at what two rotor positions should the voltmeter read maximum voltage?
Last Answer : . 150º and 330º
Description : What is the amplitude and voltage induced into the rotor when the CX is turned 90º while the CT remains on electrical zero?
Last Answer : The voltage is maximum and in phase with the ac excitation voltage to the CX.
Description : When a CT is on electrical zero, what is the relationship between its rotor and the S2 winding?
Last Answer : They are perpendicular to each other.
Description : What three things prevent a CT rotor from turning when voltages are applied to its stator windings?
Last Answer : The rotor is specially wound, it is never connected to an ac supply, and its output is always applied to a high-impedance load.
Description : What is the angular position of a TX rotor when it is
Last Answer : The S1 and S3 leads are reversed between the TX and the TDX, and the R1 and R3 leads are reversed between the TDX rotor and the TR.
Description : In a TDX system when does the TR rotor follow the TX rotor exactly?
Last Answer : . When the TDX rotor is on 0º.
Description : What is the name given to the angle through which a transmitters rotor is mechanically rotated?
Last Answer : Signal.