An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.
The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?
A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for
Last Answer : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles
Last Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.
State the function of following parts in Induction motor. (i) Stator (ii) Slip rings
Last Answer : Name of part Function Stator 1) Stator frame supports the core, terminal box and protects the inner parts. 2) Stator core houses stator winding. 3) Stator winding ... ) Provides facility to connect external resistance to rotor circuit through brushes for starting and control.
Last Answer : The purpose of stator winding in the compensated repulsion motor is to improve power factor and provide better speed regulation.
Salient pole rotor is use for which speed?
Last Answer : Salient pole rotor is use for low and medium speed prime movers.
Which rotor is use for high speed in turbo alternators?
Last Answer : Non-salient pole rotor is used for high speed in turbo alternators.
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?
Last Answer : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.
Last Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
If the field of synchronous motor is under excited, power factor will be?
Last Answer : If the field of synchronous motor is under excited, power factor will be lagging.
Explain with neat circuit diagrams the procedures to perform no load and blocked rotor tests on three phase induction motor.
The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be
Last Answer : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be 0.5 Ohm
Ratio of the rotor reactance X to the rotor resistance R for a two-phase servo motor (A) is equal to that of a normal induction motor (B) is less than that of a normal induction motor (C) ... than that of a normal induction motor (D) may be less or greater than that of a normal induction motor
Last Answer : C
Last Answer : Locked rotor current of a shaded pole motor is slightly more than full load current.
Last Answer : The rotor of a hysteresis motor is made of chrome steel.
Last Answer : In a hysteresis motor, the rotor must have retentivity.
Last Answer : The rotor developed by a single-phase motor at starting is zero.
What is the rotor of a motor?
Last Answer : Rotor is the rotating or moving part in motor and generator.
Last Answer : The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.
If we change the excitation of synchronous machine will it affect on motor speed?
Last Answer : No, If we change the excitation of synchronous machine it will not affect on motor speed.
Synchronous motor always runs at which speed?
Last Answer : Synchronous motor always runs at synchronous speed.
The ability of materials to become polarized under an applied electric field is called _______ A) Ferroelectricity B) Paraelectricity C) Polectricity D) None of these
Last Answer : The ability of materials to become polarized under an applied electric field is called Paraelectricity
Briefly describe the electric field of a static charge.
The electric field inside a hollow conducting sphere ________ A) Depends on the diameter of the sphere B) Varies according to the direction of earth’s magnetic poles C) Is zero D) None of these
Last Answer : The electric field inside a hollow conducting sphere Is zero
MOSFET uses the electric field of?
Last Answer : MOSFET uses the electric field of gate capacitance.
Is electric potential zero when electric field is zero?
Last Answer : Yes .If electric field is zero then electric potential is zero , not even one.
What is the direction of the induced electric field?
Last Answer : It is in opposite direction to the one that produced it.
Can the electric field between two positive charges be zero?
Last Answer : It can only if they have equal charges.
What is the direction of the electric field?
Last Answer : Electric field is at right angle widh flow of current (right hand rule).
How can a magnetic field be used to generate an electric current?
Last Answer : Magnetic field can be used to generate electric current on a condition that it is on a rate of changing magnetic flux. (Faraday's law)
Last Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.
Last Answer : If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.
Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.
Field control of DC motor
Last Answer : Field control of DC motor
What is a stator in a motor?
Last Answer : Stator is the stationary part of the electrical machine both motor and generator. In motor it provide the rotating magnetic field to drive rotor and in case of generator stator convert rotating magnetic field into current.
Last Answer : For the same H.P. rating and full load speed, following motor has poor starting torque differentially compounded.
Last Answer : The speed/load characteristics of a universal motor is same as that of D.C. series motor.
A _________ is used to measure the stator % winding temperature of the generator. (A) Thermocouple (B) Pyrometer (C) Resistance thermometer (D) Thermometer
Last Answer : A Resistance thermometer is used to measure the stator % winding temperature of the generator.
Last Answer : The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a two-phase winding.
What causes stator failure?
Last Answer : Stator faliur due to moistur. Due to priodically heatup of winding.
Write the steps to rewind an electric motor
Describe the reason of using dc series motor for electric trains.
Last Answer : Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up ... torque - speed characteristics of DC series motors match, these motors are suitable for electric trains
The motor used for electric traction is (1) D.C. shunt motor (3) D.C. series motor (2) D.C. compound motor (4) Synchronous motor
Last Answer : The motor used for electric traction is D.C. series motor
Last Answer : The power mentioned on the name plate of an electric motor indicates the output power available at the shaft.
Last Answer : The electric motor used in portable drills is universal motor.
What is an electric motor drive?
Last Answer : An electric drive is a complex electromechanical system that drives various actuators in industrial and industrial work machines. In this case, control is carried out using a technological process ... calculation of the kinematic and load characteristics of the electric drive is carried out.
How does an electric motor works?
Last Answer : In the electric motor there are two types of part 1)moving and 2)stationary In stationary part containing field winding whis use to provide uniform maganetic field it at inner side of yoke In moving ... on it and this force is from all direction we can say it is torque.and motor armature rotates
What is the use of an electric motor?
Last Answer : Electrical motors are use for converting electrical energy to mechanical energy. It may be use in fans, pumps, washing machine, cranes, trains, factories, industries etc.
Speed control of the motor using TRIAC
Last Answer : Speed control of the motor using TRIAC: This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply. The variable resistor, VR1 is used ... meaning that it may not trigger at the exact same point for each positive and negative half cycle.
Why does the speed of a DC shunt motor decrease as the load increases?
Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.