How do induction heaters work?

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Description : How does a single phase induction motor work?

Answer : As we know that single phase induction is not self started because for self started we require atleast two revolving field but single phase induction motor has only one. So we provide extra ... 1phase IM classified as split phase IM, capacitor start capacitor run, capacitor start induction run.

Description : How does electric locomotive work?

Answer : Electric  locomotives  are  powered   by  motors  connected  to  battery  or  any  supply . The  electric  supply  is  connected  to  a  motor  which  drives  set  of  gears  connected  to  wheels.

Description : Why using megger ? how to work megger?

Answer : Megger is all about safety. You need to use cables that can meet your demand without putting anyone at risk through earth leakages. So Megger is all about testing cable insulation. You use an insulation tester resistant meter to make sure your cables are standard and properly insulated.

Description : How does the Arduino work?

Description : How does a PSC motor work?

Description : What is a transducer and how does it work?

Answer : An electronic device that converts one form of energy to another form.for example a transducer is used in microphone to convert speech signals to electrical signal.on the other hand,transducer is used to convert an electrical signal to speech signals in speakers.

Description : How does signal processing work?

Description : What is a servo motor and how does it work?

Answer : It is a simple electrical motor that is operated by AC or DC signal in order to provide a precise angular motion for a given electrical signal.

Description : How does an operational amplifier work?

Description : The range of frequencies used in induction heating is :  (A) 0-25 Hz  (C) less than 200 Hz  (B) 50 to 100 Hz  (D) more than 1 kHz

Answer : The range of frequencies used in induction heating is : more than 1 kHz

Description : Is induction heating safe?

Description : What to eat at work?

Answer : If your work schedule does not provide for a clear lunch break, and the company does not have kitchens or canteens, then you will have to take care of your meals at work yourself. What foods are commonly ... add a jar of baby puree to it. You will receive a delicious, quick and very healthy lunch.

Description : Draw a neat sketch and explain the accessory used to support long work.

Answer : Accessory to support long work: A steady rest is a tool for a lathe, enabling a machinist to make deep cuts in long, slender stock, bore out thin pieces of metal, and generally keeps thin stuff straight. ... tool that follows the cutter, a steady rest is firmly attached to the bed of a lathe.

Description : State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows:  1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine 

Description : The unit of work or energy in S.I. units is

Answer : The unit of work or energy in S.I. units is joule.

Description : What is the work of MOSFET?

Description : Why does a transformer only work with an AC supply?

Answer : The transformer work depends on the induction as main principle ,for that AC is the right means

Answer : Unit of work is Joule denoted by capital J .

Description : Do AC induction motors have back EMF?

Description : How is a three phase cage induction motor self starting?

Answer : Any type of induction motor is self starting. Because the reason for torqe production require two flux displaced by some angle theta.If theta is constant with time then torqe will be constant;if ... torqe also pulsating. In induction motor this angle theta is not it is self starting 

Description : how can we reverse the direction of rotation of three phase induction motor ?

Answer : The direction of rotation of three phase induction motor can be reversed by plugging i.e by changing any two out of three phases of the supply to the stator of the Induction motor terminal.

Description : Explain the working principle of induction motor. 

Answer : Working principle of induction motor: * When the motor is excited with three-phase supply, three-phase stator winding carries three-phase currents & produces a rotating magnetic field of constant magnitude and ... , which tend to move the rotor in the same direction as the rotating magnetic field. 

Description : Explain the activities carried out during weekly maintenance of 3 ph. Induction motor. 

Answer : Activities Carried out During Weekly Maintenance of 3 ph. Induction Motor:  1) Check belt tension. In cases where this is excessive it should immediately be reduces and in the case of sleeve ... and cooled by oil mist systems its important to check the oil mist flow paths/pressure components.

Description : State the function of following parts in Induction motor. (i) Stator (ii) Slip rings

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.

Description : Electro Magnetic Induction

Answer : Electro Magnetic Induction

Description : List the energy conservation technique in induction motor. 

Answer : Following are the list of energy conservation techniques in electrical motors: 1) Reduction in iron losses by using low loss silicon steel core material laminated to thinner dimension. 2) Using bigger length ... at light load. 13) By rewinding in induction motor 14) By motor survey

Description : With a neat sketch give the working of shaded pole induction motor.

Answer : Explanation: It has squirrel cage rotor and salient pole stator. The stator poles are shaded partially by short circuited conductor band to create the phase difference between the fluxes emerging from shaded ... rotating magnetic field in the air-gap and torque is exerted on the squirrel cage rotor.

Description : Define Faraday’s first law of electromagnetic induction. 

Answer : Faraday’s First Law: Whenever a changing magnetic flux links with a conductor, an emf is induced in that conductor.  OR  When a conductor cuts across magnetic field, an emf is induced in that conductor.

Description : Explain with neat circuit diagrams the procedures to perform no load and blocked rotor tests on three phase induction motor.

Description : Explain the need and steps to conduct the reduced voltage running up test on the three phase induction motor.

Description : What will happen if the induction motor runs at synchronous speed ?

Answer : Since there is always slip present in rotor it cannot run at synchronous speed no current will be developed hence no torque will developed

Description : Define Slip of Induction Motor.

Answer : Slip: It is the ratio of relative speed of rotor (difference between synchronous speed and rotor speed) to the synchronous speed of rotating magnetic field.  Slip = (NS – N) / NS  where , NS = synchronous speed, N = speed of rotor

Description : Enlist any four advantages of induction heating. 

Answer : Advantages of Induction heating

Description : Explain the working of a single phase capacitor start induction motor. 

Answer : Single phase capacitor start induction motor

Description : State any four advantages of three phase induction motor. 

Answer : Advantages of three phase induction motor

Description : With a neat diagram explain doubly fed induction generator (DFIG). 

Answer : Diagram of Doubly fed induction generator (DFIG):  Explanation :-  DFIG can feed power through the stator as well as rotor to the grid. The stator is directly connected to the fixed frequency ... voltage is 690 V AC. So it must be step up to 33 KV to connect to power grid.  

Description : Explain Squirrel Cage Induction Generator (SCIG) and also draw a diagram. 

Answer : Explanation (Operation):- In this system gearbox is used to increase the speed of high speed shaft as per design. IG require reactive power for excitation. Rotor of SCIG is ... , variable voltage output of the generator into the fixed frequency, fixed voltage output required for grid. 

Answer : Energy conservation technique in induction motor by minimizing idle and redundant running of motor: 1) Loss of energy as the no load power drawn is approximately about 12% to 16% of rated ... to unnecessary line losses. 4) Reduction in overall system energy efficiency over period of time.

Description : State and explain any four factors governing selection of induction motor.

Answer : The factors governing the selection of Induction motor: 1) Load torque required at normal speed matches with available torque of motor. 2) Break down torque or pull out torque or maximum torque ... If selecting energy efficient motor the cost benefit analysis over the long run must be worked out.

Description : Explain energy conservation technique “by improving power quality” for induction motor.

Answer : Energy conservation method in induction motor by improving power quality: Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage unbalance, maintaining ... losses can be minimized by using harmonic filter thus reducing the harmonics in the system.

Description : Split phase induction motor

Answer : Split phase induction motor : There are two windings used in split phase induction motor. It is a type of single-phase induction motor. There are two winding one is called main winding and ... motor have low starting torque it is used for small fans, blowers, centrifugal pumps, grinders etc.

Description : State starters used for i) 3-Ph squirrel cage induction motor (3HP) ii) D.C. motor 

Answer : Name the starters used for following motors : i) 3 H.P. 3-Ph squirrel cage I.M: i) DOL starter OR ii) Star-Delta Starter OR ii) Auto transformer starter OR iii) Soft start starter.  ii) D.C Shunt Motor : 1) Armature resistance starter (Three Point Starter) OR 2) Four Point Starter 

Description : State the function and shape of following parts used in induction type energy meter: i) Series magnet ii) Shunt magnet iii) Al disc iv) Brake magnet

Answer : i) Series magnet: produce flux proportional to current (load current) of circuit and interact in the aluminum disc with flux produced by voltage magnet for torque production. Its shape is like letter U.  ii) ... : brakes the motion of the aluminum disc or slows it down. Its shape is like letter C. 

Description : Draw a neat sketch of 1-ph induction type energy meter and write operating principle of it. 

Answer : Operating Principal:- The disc is placed between the two-flux due to pressure coil and flux due to current coil, which will set up torque on the disc which is proportional to power causing the ... is proportional to voltage, the second carries a current coil so its flux is proportional to current.

Description : List any four errors in induction type energy meter. Give method of compensation for each.

Answer : Errors in Induction Type Energy Meter with their Compensation:  1) Error due to friction: This error can be compensated by the additional shading band provided on the shunt electromagnet.  2) Phase ... error: This error can be compensated by providing a flux diverter' to the current magnet. 

Description : State Faraday's law of electromagnetic induction.

Answer : First Law: - Whenever change in the magnetic flux linked with a coil or conductor, an EMF is induced in it. OR Whenever a conductor cuts magnetic flux, an EMF is induced in conductor.  Second Law: ... of induced EMF is directly proportional to (equal to) the rate of change of flux linkages.

Description : In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high ... the outer high resistance winding. (D) Large current flows through the inner low resistance winding.

Answer : In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.

Description : A change of 4% in the supply voltage to an induction motor will produce a change of approximately

Answer : A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque

Description : 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

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

Description : In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will  (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times

Answer : In an induction motor if the flux density is one-half, of its normal value then the torque will reduce to one-fourth

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