Electrical engineering interview questions and answers book


 

Whether you are preparing to interview a candidate or applying for a job, review our list of top Electrical Engineer interview questions and answers. Electrical engineering Interview Questions and Answers - Free download as PDF File .pdf), Text File .txt) or read online for free. This book is based on some of the Electrical and Electronics Engineering interview questions with answers. I think so; it can help you to increase your basic .

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Electrical Engineering Interview Questions And Answers Book

Electrical Engineering Interview Questions and Answers ( + Important good book for electrical engineers but need a little bit more clarification of answers. In above article, we have kept the most asked electrical engineering Interview Questions with their detailed answers to it. + INTERVIEW QUESTIONS: FOR FRESH ELECTRICAL ENGINEERS This Book contains + Electrical Interview Question for Electrical Engineering you can answer almost 80% questions asked in any electrical interview session.

This book is based on some of the Electrical and Electronics Engineering interview questions with answers. I think so; it can help you to increase your basic knowledge and confidence in the interview and also written examination. I collect all the data from some books and with the help of internet. Any suggestion in favour of this book will be cordially and thankfully received. However, I am responsible for any remaining errors or inadequacies. Dhaka, February Why are not 4 or something else? One end of the wire is connected to the phase and the remaining one connected to earth instead of neutral. The bulb will glow or not? If yes then what is the need of neutral? And in an Electric train during running, we did not feel any Shock? Define with cause and where be use it Device? C motor is used in the fan ceiling fan, exhaust fan, pedestal fan, bracket fan etc which are find in the houses? Pi value and simple definition of polarization index? Why can't use ACB?

Battery banks are in connected in series or parallel and why? Battery banks are always connected in series in order to get a multiplied voltage where the AH or current capacity remaining same.

What is inrush current? Inrush current is the current drawn by a piece of electrically operated equipment when power is first applied. It can occur with AC or DC powered equipment, and can happen even with low supply voltages. In a Tap changing transformer where is the tap connected, is it connected in the primary side or secondary side? Tapings are connected to high voltage winding side, because of low current. If we connect tapings to low voltage side, sparks will produce while tap changing operation due to high current.

Why transformer ratings are in kva? Since the power factor of transformer is dependent on load we only define VA rating and does not include power factor. In case of motors, power factor depend on construction and hence rating of motors is in KWatts and include power factor. Define what is difference between fuse and breaker? Fuses are burned at the time of over current flows in the circuit but breakers are just open not burn at the time of over current flow.

Fuses are used in only one time but breakers are used by multiple number of times. What is the difference between delta-delta, delta-star transformer? Delta-star is a distribution kind of transformer where from secondary star neutral is taken as a return path and this configuration is used for Step down voltage phenomena.

Capacitor is load free component but why ampere meter shows current when capacitor bank breaker close? As we know that Electrical is having two type of load, Active and Reactive. Traction implies with the electric power for traction system i. Now a day, magnetic traction is also utilised for bullet trains. Essentially dc motors are utilized for electric traction systems.

Pu stands for per unit in power system. Define stepper motor. What is the use of stepper motor? The motor which work or act on the applied input pulse in it, is called as stepper motor. This stepper motor is under the category of synchronous motor, which often does not fully depend of complete cycle. It likes to works in either direction related to steps. What is a differential amplifier?

Also, explain CMRR. Differential Amplifier: The amplifier, which is used to amplify the voltage difference between two input-lines neither of which is grounded, is called differential amplifier. This reduces the amount of noise which is injected into the amplifier, because any noise appearing simultaneously on both the input-terminals as the amplifying circuitry rejects it being a common mode signal.

It can be defined as the ratio of differential voltage-gain to common made voltage gain. If a differential amplifier is perfect, CMRR will be infinite because in that case common mode voltage gain would be zero.

What is use of lockout relay in ht voltage? This relay is powered by the same electrical source as the control power which is operated by a key lock switch. What types domain of Laplace transforms? What behavior can Laplace transform predict how the system work? Types domain of Laplace transforms is s-domain, Laplace transforms provide a method to find position, acceleration or voltage the system will have.

In the magnetic fluxes, what is the role of armature reaction? The armature flux has an important role for the running condition. This armature flux can oppose the main flux or it may support the main flux for better running condition.

This effect of supporting and opposing of main flux to armature flux is called armature reaction. Explain thin film resistors and wire-wound resistors Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate. Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. During this process, the value of the resistance is monitored closely and cutting of grooves is stopped as soon as the desired value of resistance is obtained.

Wire wound resistors — length of wire wound around an insulating cylindrical core are known as wire wound resistors. These wires are made of materials such as Constantan and Manganin because of their high resistivity, and low temperature coefficients.

The complete wire wound resistor is coated with an insulating material such as baked enamel. What are the operation carried out in Thermal power station? The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine, the turbine which is coupled with the generator generates the electricity. What is the difference between Electronic regulator and ordinary rheostat regulator for fans?

The difference between the electronic and ordinary regulator is the fact that in electronic reg. In electronic regulator triac is employed for speed control. A two phase motor is often a motor with the the starting winding and the running winding have a phase split. What does quality factor depend on in resonance? Quality factor q depends on frequency and bandwidth. What are the types of power in electrical power? There are normally three types of power are counted in electrical power.

They are,. What are the advantages of VSCF wind electrical system? Advantages of VSCF wind electrical system are:. What is slip in an induction motor? Slip can be defined as the distinction between the flux speed Ns and the rotor speed N. Speed of the rotor of an induction motor is always less than its synchronous speed. State the difference between generator and alternator?

Generator and alternator are two devices, which converts mechanical energy into electrical energy. Both have the same principle of electromagnetic induction, the only difference is that their construction.

Generator persists stationary magnetic field and rotating conductor which rolls on the armature with slip rings and brushes riding against each other, hence it converts the induced emf into dc current for external load whereas an alternator has a stationary armature and rotating magnetic field for high voltages but for low voltage output rotating armature and stationary magnetic field is used. What is ACSR cable and where we use it? Why star delta starter is preferred with induction motor? Star delta starter is preferred with induction motor due to following reasons:.

State the difference between generator and alternator Generator and alternator are two devices, which converts mechanical energy into electrical energy. Why AC systems are preferred over DC systems? Due to following reasons, AC systems are preferred over DC systems: It is easy to maintain and change the voltage of AC electricity for transmission and distribution.

Plant cost for AC transmission circuit breakers, transformers etc is much lower than the equivalent DC transmission c. When a large fault occurs in a network, it is easier to interrupt in an AC system, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt. How can you relate power engineering with electrical engineering? Power engineering is a sub division of electrical engineering. It deals with generation, transmission and distribution of energy in electrical form.

Design of all power equipments also comes under power engineering. Power engineers may work on the design and maintenance of the power grid i. What are the various kind of cables used for transmission? Cables, which are used for transmitting power, can be categorized in three forms:.

Why back emf used for a dc motor? The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back emf.

Its value depends upon the speed of rotation of the armature conductors. In starting, the value of back emf is zero. Slip can be defined as the difference between the flux speed Ns and the rotor speed N. Explain the application of storage batteries. Storage batteries are used for various purposes, some of the applications are mentioned below:.

Explain advantages of storage batteries Few advantages of storage batteries are mentioned below:. What are the different methods for the starting of a synchronous motor.

Electrical and Electronics Engineering Interview Questions and Answers

Starting methods: Synchronous motor can be started by the following two methods:. Name the types of motors used in vacuum cleaners, phonographic appliances, vending machines, refrigerators, rolling mills, lathes, power factor improvement and cranes.

Following motors are used: State Maximum power transfer theorem The Maximum power transfer theorem explains about the load that a resistance will extract from the network. This includes the maximum power from the network and in this case the load resistance is being is equal to the resistance of the network and it also allows the resistance to be equal to the resistance of the network.

This resistance can be viewed by the output terminals and the energy sources can be removed by leaving the internal resistance behind. Explain different losses in a transformer. There are two types of losses occurring in transformer:. Explain different types of D. C motors? Give their applications Different type of DC motors and their applications are as follows: Explain the process of commutation in a dc machine.

Explain what are inter-poles and why they are required in a dc machine. It is phenomenon when an armature coil moves under the influence of one pole- pair; it carries constant current in one direction. As the coil moves into the influence of the next pole- pair, the current in it must reverse. This reversal of current in a coil is called commutation.

Several coils undergo commutation simultaneously. The reversal of current is opposed by the static coil emf and therefore must be aided in some fashion for smooth current reversal, which otherwise would result in sparking at the brushes.

The aiding emf is dynamically induced into the coils undergoing commutation by means of compoles or interpoles, which are series excited by the armature current. These are located in the interpolar region of the main poles and therefore influence the armature coils only when these undergo commutation.

Comment on the working principle of operation of a single-phase transformer. Working principle of operation of a single-phase transformer can be explained as An AC supply passes through the primary winding, a current will start flowing in the primary winding. As a result, the flux is set. This flux is linked with primary and secondary windings. Hence, voltage is induced in both the windings.

Now, when the load is connected to the secondary side, the current will start flowing in the load in the secondary winding, resulting in the flow of additional current in the secondary winding. The voltage induced in secondary coil is known as mutually induced voltage. Hence, transformer works on the principle of electromagnetic induction. Define the following terms: It is the capacity of the power system to serve all power demands without failure over long periods.

Maximum Demand: It is maximum load demand required in a power station during a given period. Reserve generating capacity: Extra generation capacity installed to meet the need of scheduled downtimes for preventive maintenance is called reserve-generating capacity. As the percentage of the time a unit is available to produce power whether needed by the system or not. Mention the disadvantages of low power factor? How can it be improved?

Disadvantages of low power factor:. State the methods of improving power factor? Methods of improving power factor:. State the factors, for the choice of electrical system for an aero turbine. The choice of electrical system for an aero turbine is guided by three factors:. Explain the terms real power, apparent power and reactive power for ac circuits and also the units used.

Define the following: Average demand, Maximum demand, Demand factor, Load factor.

Explain forward resistance, static resistance and dynamic resistance of a pn junction diode. How does Zener phenomenon differ from Avalanche breakdown? The phenomenon when the depletion region expands and the potential barrier increases leading to a very high electric field across the junction, due to which suddenly the reverse current increases under a very high reverse voltage is called Zener effect.

Zener-breakdown or Avalanche breakdown may occur independently or both of these may occur simultaneously. Diode junctions that breakdown below 5v are caused by Zener Effect. Junctions that experience breakdown above 5v are caused by avalanche-effect. The Zener-breakdown occurs in heavily doped junctions, which produce narrow depletion layers. The avalanche breakdown occurs in lightly doped junctions, which produce wide depletion layers.

Explain thin film resistors and wire-wound resistors a. Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate.

This reduces the amount of noise injected into the amplifier, because any noise appearing simultaneously on both the input-terminals as the amplifying circuitry rejects it being a common mode signal.

If a differential amplifier is perfect, CMRR would be infinite because in that case common mode voltage gain would be zero. What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans? The difference between the electronic and ordinary electrical regulator is that in electronic regulator power losses are less because as we decrease the speed the electronic regulator gives the power needed for that particular speed but in case of ordinary rheostat type regulator, the power wastage is same for every speed and no power is saved.

In electronic regulator, triac is employed for speed control by varying the firing angle speed and it is controlled but in rheostatic ,control resistance is decreased by steps to achieve speed control. What does the KVAR means?

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DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load. What is meant by armature reaction? The effect of armature flu to main flux is called armature reaction.

The armature flux may support main flux or opposes main flux. What is ACSR cable and where we use it? What is vacuum circuit breaker? A breaker is normally used to break a circuit. While breaking the circuit, the contact terminals will be separated.

At the time of separation an air gap is formed in between the terminals. Due to existing current flow the air in the gap is ionized and results in the arc. Various mediums are used to quench this arc in respective CB's. But in VCB the medium is vacuum gas. Since the air in the CB is having vacuum pressure the arc formation is interrupted. VCB's can be used up to 11kv. What is the link between Voltage and Form Factor?

Voltage is an electrical field form factor is the actual size and shape of a device or piece of hardware. What will happen when power factor is leading in distribution of power? If there is high power factor, i. Losses in form of heat will be reduced, 2. It also reduces over heating of transformers.

Uninterrupted power supply is mainly use for short time. Means according to ups VA it gives backup. Online ups having high volt and amp for long time backup with high dc voltage. But ups start with 12v dc with 7 amps. But inverter is start with 12v,24,dc to 36v dc and amp to amp battery with long time backup. What is the significance of vector grouping in Power Transformers? Every power transformer has a vector group listed by its manufacturer.

Fundamentally it tells you the information about how the windings are connected delta or wye and the phase difference between the current and voltage. What is 2 phase motor? A two phase motor is a motor with the starting winding and the running winding have a phase split. Where the auxiliary winding and the control winding have a phase split of 90 degree.

What is the advantage of vvvf drives over non vvvf drives for EOT cranes? Advantages- 1. Smooth start and stop. No jerking of load. Exact positioning 4. Better protection for motor. Reliability of break shoe.

Programmable break control. Easy circuitry 9. Reduction in controls Which type of A. Its Single Phase induction motor which mostly squirrel cage rotor and are capacitor start capacitor run. Give two basic speed control scheme of DC shunt motor? By using flux control method: So by changing the current the flux produced by the field winding can be changed, and since speed is inversely proportional to flux speed can be controlled 2. Armature control method: What is the Polarization index value?

Its ratio between insulation resistance IR i. In simple, synchronous generator supplys both active and reactive power but asynchronous generator induction generator supplys only active power and observes reactive power for magnetizing.

This type of generators is used in windmills. Why syn. Synchronous machines have capability to work on different power factor or say different imaginary power varying the field emf.

Hence syn. Enlist types of dc generator? Generators are classified into two types 1 Separately excited d. It is important part in Synchronous Generators; it controls the output voltage of the generator by controlling its excitation current.

7 Electrical Engineer Interview Questions and Answers | nbafinals.info

Thus it can control the output Reactive Power of the Generator. What is an exciter and how does it work? There are two types of exciters, static exciter and rotary exciter. Purpose of exciter is to supply the excitation dc voltage to the fixed poles of generator.

Rotary exciter is an additional small generator mounted on the shaft of main generator. Initial voltage is built up by residual magnetism. It gives the starting torque to the generator. What is the difference between a four point starter and three point starter? The shunt connection in four point starter is provided separately form the line where as in three point starter it is connected with line which is the drawback in three point starter.

Actually the thing is vacuum has high arc quenching property compare to air because in VCB, the die electric strengths equal to 8 times of air. That y always vacuum used as in HT breaker and air used as in LT. What is the difference between surge arrestor and lightning arrestor? LA is installed outside and the effect of lightning is grounded, where as surge arrestor installed inside panels comprising of resistors which consumes the energy and nullify the effect of surge.

What is synchronous Condenser? An overexcited synchronous motor running at no- load and used for power-factor correction is called synchronous condenser. It is also called synchronous capacitor. It is used in a large system where the use of static capacitor is inefficient and expensive.

It is used for power-factor correction. What happens if I connect a capacitor to a generator load?

ELECTRICAL ENGINEERING INTERVIEW QUESTIONS AND ANSWER

Connecting a capacitor across a generator always improves power factor, but it will help depends up on the engine capacity of the alternator, other wise the alternator will be over loaded due to the extra watts consumed due to the improvement on pf. Secondly, don't connect a capacitor across an alternator while it is picking up or without any other load. Explain the working principal of the circuit breaker? Circuit Breaker is one which makes or breaks the circuit.

Under normal condition the moving contact comes in contact with fixed contact thereby forming the closed contact for the flow of current. How many types of cooling system it transformers? ONAN oil natural, air natural 2.

ONAF oil natural, air forced 3. OFAF oil forced, air forced 4. ODWF oil direct, water forced 5. Why the capacitor works on ac only? Generally capacitor gives infinite resistance to dc components i. It allows the ac components to pass through.

What is the function of anti-pumping in circuit breaker? When breaker is close at one time by close push button, the anti pumping contactor prevent re close the breaker by close push button after if it already close. What is stepper motor? Stepper motor is the electrical machine which acts upon input pulse applied to it. It is one type of synchronous motor which runs in steps in either direction instead of running in complete cycle. So, in automation parts it is used. What is meant by insulation voltage in cables?

It is the property of a cable by virtue of it can withstand the applied voltage without rupturing it is known as insulation level of the cable. What is Ferranti effect? Output voltage is greater than the input voltage or receiving end voltage is greater than the sending end voltage. What is power factor? Power factor should be high in order to get smooth operation of the system. Low power factor means losses will be more. It has to be ideally 1. If pf is poor ex: Tell me in detail about c. The term C.

T means current transformer, and the term P. T means potential transformer. In circuit where measurements of high voltage and high current is involved they are used there. Particularly when a measuring device like voltmeter or ammeter is not able to measure such high value of quantity because of large value of torque due to such high value it can damage the measuring device. So, CT and PT are introduced in the circuits.

They work on the same principle of transformer, which is based on linkage of electromagnetic flux produced by primary with secondary.

They work on the ratio to they are designed. Same is the operation of PT but measuring voltage. There are a Transformer and an induction machine. The motor has max load current compare to that of transformer because the motor consumes real power. And the transformer is only producing the working flux and its not consuming. Hence the load current in the transformer is because of core loss so it is minimum.

Why in a three pin plug the earth pin is thicker and longer than the other pins? It is longer because the First to make the connection and last to disconnect should be earth Pin. This assures Safety for the person who uses the electrical instrument. How to calculate capacitor bank value to maintain unity power factor with some suitable example?

What is boucholz relay and the significance of it in to the transformer? Boucholz relay is a device which is used for the protection of transformer from its internal faults; it is a gas based relay. What is SF6 Circuit Breaker? SF6 is Sulpher hexa Fluoride gas. What is the difference between Isolator and Circuit Breaker? Isolator is an off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintenance on downstream circuits.

It is manually operated and does not contain any solenoid unlike circuit breaker. It should not be operated while it is having load. First the load on it must be made zero and then it can safely operated.

Its specification only rated current is given. But circuit breaker is onload automatic device used for breaking the circuit in case of abnormal conditions like short circuit, overload etc.

MCB is miniature circuit breaker which is thermal operated and use for short circuit protection in small current rating circuit. MCCB moulded case circuit breaker and is thermal operated for over load current and magnetic operation for instant trip in short circuit condition.

Under voltage and under frequency may be inbuilt. Normally it is used where normal current is more than A. Define IDMT relay? It is an Inverse Definite Minimum Time relay. In IDMT relay its operating is inversely proportional and also a characteristic of minimum time after which this relay operates.

It is inverse in the sense; the tripping time will decrease as the magnitude of fault current increase. What are the transformer losses? Copper losses are caused by the resistance of the wire I2R. Magnetic losses are caused by eddy currents and hysteresis in the core. Copper loss is a constant after the coil has been wound and therefore a measurable loss. Hysteresis loss is constant for a particular voltage and current.

Eddy-current loss, however, is different for each frequency passed through the transformer. Where should the lighting arrestor is placed in distribution lines? Near distribution transformers and out going feeders of 11kv and incoming feeder of 33kv and near power transformers in sub-stations. Why we do 2 types of earthing on transformer i.

The two types of earthing are Familiar as Equipment earthing and system earthing. In Equipment earthing: System Earthing: In this neutral of the supply source Transformer or Generator should be grounded. With this, in case of unbalanced loading neutral will not be shifted. So that unbalanced voltages will not arise. We can protect the equipment also.

With size of the equipment transformer or alternator and selection of relying system earthing will be further classified into directly earthed, Impedance earthing, resistive NGRs earthing. What is the general difference between DC and AC machine? In DC machine armature rotates and the field is stationary, In AC machine armature is stationary and the field is rotating. DC machine contains commutator and brush, AC machine contains slip ring and brush.

What are the advantages of star-delta starter with induction motor? Starting current is reduced to times of current of Direct online starting. Hence the starting current is reduced; the voltage drops during the starting of motor in systems are reduced.

Why is the starting current high in a DC motor? At starting, E b is zero. What is meant by regenerative braking? When the supply is cut off for a running motor, it still continue running due to inertia. In order to stop it quickly we place a load resistor across the armature winding and the motor should have maintained continuous field supply.

So that back e. This type of breaking is called as "Regenerative Breaking". Why series motor cannot be started on no-load?

Series motor cannot be started without load because of high starting torque. Why we use ac system in India why not dc? Secondly it is much easier to change the voltage of AC electricity for transmission and distribution.

When a fault on the network occurs, a large fault current occurs. In an AC system this becomes much easier to interupt, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt. Which type of motor is used in trains, what is the rating of supply used explain Working principal? Dc series is in the trains to get high starting torque while starting of the trains and operating voltage is v dc.

Battery banks are in connected in series or parallel and why? Battery banks are always connected in series in order to get a multiplied voltage where the AH or current capacity remaining same.

Ex : 24 nos. What is inrush current? Inrush current is the current drawn by a piece of electrically operated equipment when power is first applied. It can occur with AC or DC powered equipment, and can happen even with low supply voltages. In a Tap changing transformer where is the tap connected, is it connected in the primary side or secondary side?

Tapings are connected to high voltage winding side, because of low current. If we connect tapings to low voltage side, sparks will produce while tap changing operation due to high current.

Why transformer ratings are in kva? Since the power factor of transformer is dependent on load we only define VA rating and does not include power factor.

In case of motors, power factor depend on construction and hence rating of motors is in KWatts and include power factor. Define what is difference between fuse and breaker? Fuses are burned at the time of over current flows in the circuit but breakers are just open not burn at the time of over current flow.

Fuses are used in only one time but breakers are used by multiple number of times. What is the difference between delta-delta, delta-star transformer? Delta-star is a distribution kind of transformer where from secondary star neutral is taken as a return path and this configuration is used for Step down voltage phenomena.

Capacitor is load free component but why ampere meter shows current when capacitor bank breaker close? As we know that Electrical is having two type of load, Active and Reactive. Traction implies with the electric power for traction system i. Now a day, magnetic traction is also utilised for bullet trains. Essentially dc motors are utilized for electric traction systems. Pu stands for per unit in power system.

Define stepper motor. What is the use of stepper motor?

The motor which work or act on the applied input pulse in it, is called as stepper motor. This stepper motor is under the category of synchronous motor, which often does not fully depend of complete cycle. It likes to works in either direction related to steps. What is a differential amplifier? Also, explain CMRR. Differential Amplifier: The amplifier, which is used to amplify the voltage difference between two input-lines neither of which is grounded, is called differential amplifier.

This reduces the amount of noise which is injected into the amplifier, because any noise appearing simultaneously on both the input-terminals as the amplifying circuitry rejects it being a common mode signal.

CMRR: It can be defined as the ratio of differential voltage-gain to common made voltage gain. If a differential amplifier is perfect, CMRR will be infinite because in that case common mode voltage gain would be zero. What is use of lockout relay in ht voltage? This relay is powered by the same electrical source as the control power which is operated by a key lock switch. What types domain of Laplace transforms? What behavior can Laplace transform predict how the system work?

Types domain of Laplace transforms is s-domain, Laplace transforms provide a method to find position, acceleration or voltage the system will have.

In the magnetic fluxes, what is the role of armature reaction? The armature flux has an important role for the running condition. This armature flux can oppose the main flux or it may support the main flux for better running condition. This effect of supporting and opposing of main flux to armature flux is called armature reaction. Explain thin film resistors and wire-wound resistors Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate.

Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. During this process, the value of the resistance is monitored closely and cutting of grooves is stopped as soon as the desired value of resistance is obtained. Wire wound resistors — length of wire wound around an insulating cylindrical core are known as wire wound resistors.

These wires are made of materials such as Constantan and Manganin because of their high resistivity, and low temperature coefficients. The complete wire wound resistor is coated with an insulating material such as baked enamel What are the operation carried out in Thermal power station? The water is obtained in the boiler and the coal is burnt so that steam is obtained this steam is allowed to hit the turbine, the turbine which is coupled with the generator generates the electricity What is the difference between Electronic regulator and ordinary rheostat regulator for fans?

The difference between the electronic and ordinary regulator is the fact that in electronic reg. In electronic regulator triac is employed for speed control. What is 2 phase motor?

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