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 : 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 output voltage of a CT when it is set on electrical zero?
Last Answer : Zero or minimum voltage.
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 name given to the electrical output of a CT?
Last Answer : Error signal
Description : In a control synchro system, when is the output of the CT reduced to zero?
Last Answer : When the CX and CT rotors are in correspondence.
Description : 32 With S2 closed and S1 open, the current waveform in the delta winding will be [GATE 2009] A. a sinusoidal at fundamental frequency B. flat-topped with third harmonic C. only third-harmonic D. none of these
Last Answer : C. Only third harmonic
Description : A CT has 2 – secondary windings. If we use only one secondary winding can we keep the unused secondary winding short circuited?
Last Answer : No. If it is short-circuited then the ratio will not get correctly. The turns of primary winding will be shared between 2 secondary windings. So the unused secondary winding should kept open.
Description : A single-phase induction motor will only start if you spin the rotor rapidly with the line switch closed. After starting, its speed fluctuates between very slow and half-speed. The problem ... in the ________. A. starting winding B. centrifugal mechanism C. centrifugal switch D. running winding
Last Answer : Answer: D
Description : If the residual flux is absent in the rotor iron of the isolated induction generator, a) it will not run. b) it will run as induction motor c) it will burn the winding d) it will not affect the characteristic of the generator
Last Answer : Ans: A
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
Last Answer : Answer: B
Description : A single-phase induction motor fails to start. The rotor is spun rapidly with the line switch closed. Having started by this method it is noted that the motor fluctuates between a very slow ... lies in the ______ A. starting winding B. centrifugal mechanism C. centrifugal switch D. running 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. rotor conducting bars resistance
Description : A characteristic of a wound-rotor induction motor, with a high resistance rotor winding, is _____________. A. low starting torque B. high starting torque C. high speed D. low starting voltage
Description : A characteristic of an induction motor with a low resistance rotor winding is _____________. A. high starting voltage B. high starting current C. high slippage D. low starting voltage
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 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 : Which of the following statements is true concerning a polyphase synchronous propulsion motor? A. The motor is started as an induction motor. B. Resistance is gradually added to the rotor circuit. C. ... is held below the rated current. D. The field winding is energized for starting purposes only.
Last Answer : Answer: A
Description : An operating characteristic appearing on the name plates of shipboard AC motors is _____________. A. the type of winding B. input kilowatts C. temperature rise D. locked rotor torque
Last Answer : Answer: C
Description : Will rotor earth fault relay operate for earth fault in main exciter winding or RCU Diode Bridge also?
Last Answer : Yes.
Description : Harmonics are eliminated by using a) Skewing of rotor b) Distribution winding c) Short pitch winding d) All of the above
Last Answer : Ans: All of the above
Description : A synchro has (A) a 3-phase winding on rotor and a single-phase winding on stator. (B) a 3-phase winding on stator and a commutator winding on rotor. (C) a 3-phase winding on stator and a single-phase winding on rotor. (D) a single-phase winding on stator and a commutator winding on rotor.
Last Answer : Ans: C Synchros : The basic synchro unit called a synchro transmitter. It’s construction similar to that of a Three phase alternator.
Description : Direct water cooling of rotor winding presents (a) no mechanical difficulties (b) lesser mechanical difficulties (c) greater mechanical difficulties (d) none of the above
Last Answer : (c) greater mechanical difficulties
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 : A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: (1) Slip frequency (2) Supply frequency (3) Frequency corresponding to rotor speed (4) Zero
Last Answer : A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: Slip frequency
Description : What type of excitation is given to the rotor winding of a synchronous motor? (A) DC supply at 100 -250 V (B) AC supply at 400 V (C) Revolving field (D) Induction from stator currents
Last Answer : Dc supply of 100 to 250v is applied on the field circuit to make stable magnetic field which thens follow the rotating magnetic feild of stator or armature circuit.
Description : With the inputs shown below, what will be the output of S1, S2, and C2?
Last Answer : MSD of the sum.
Description : S1 and S2 are the draw downs in an observation well at times t1 and t2 after pumping. For discharge Q and coefficient of transmissibility T, the relationship, is (A) S2 - S1 = (2.3Q/ ) log10 (t2/t1) (B) S2 - S1 ... - S1 = (2.3Q/4 ) loge (t2/t1) (D) S2 - S1 = (2.3Q/4 ) loge (t1/t2
Last Answer : (B) S2 - S1 = (2.3Q/4 ) log10 (t2/t1)
Description : Our weight will be zero under all of the following conditions EXCEPT a.107 dynes b.We are at the centre of the earth c.When we are ascending in a lift with acceleration of 4.9 m/s2 d.We are orbiting in a satellite e.When we are freely faling
Last Answer : c. When we are ascending in a lift with acceleration of 4.9 m/s2
Description : An error signal is the difference between what two quantities fed to the CT (error detector)?
Last Answer : Input signal and feedback.
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 : 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.
Description : In a TDX system with standard synchro connections, the TX rotor is at 120º and the TDX rotor is at 40º. What position will the TR indicate?
Last Answer : . 80º.
Description : On the synchro schematic symbol, what indicates the angular displacement of the rotor?
Last Answer : . The position of the arrow.
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 : 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 causes a voltage to be developed across the secondary winding of a transformer?
Last Answer : The magnetic lines generated by the current in the primary cut
Description : . What three factors determine the amplitude of the voltage induced into a stator winding?
Last Answer : The amplitude of the primary voltage, the turns ratio, and the angular displacement between the rotor and the stator winding.
Description : Which of the two main types of rotors can have either a single winding or three Y-connected windings?
Last Answer : The drum or wound rotor.
Description : What is used to bias a magnetic amplifier so that the control winding remains free to accept control (input) signals?
Last Answer : A bias winding and associated circuitry.
Description : When winding a tape onto a plastic or metal reel, should the tape ever touch the reel’s flanges?
Last Answer : No. The reel is designed to hold the tape on its hub without letting the tape touch the sides of the flanges.
Description : A tape pack has gaps in the tape winding as shown in figure 2-5. What causes this condition?
Last Answer : Tape is loosely wound on reel.
Description : Tape winding errors can cause a deformed tape pack. What are four common types of tape pack deformation?
Last Answer : Cinching, pack slip, spoking, and windowing.
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 : In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
Last Answer : In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
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 air gap in an induction motor should be checked periodically with a feeler gage to detect ____________. A. rotor contact with the laminations B. changes in armature magnetic strength C. excessive bearing wear D. electrical damage to the rotor