Top 36 Electrical Engineering Interview Questions You Must Prepare 02.Mar.2024

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.

It is used with generators for charging a number of capacitor in parallel and discharging them in series.It is used when voltage required for testing is higher than the available

For lighting loads, neutral conductor is must and hence the secondary must be star winding. and this lighting load is always unbalanced in all three phases. To minimize the current unbalance in the primary we use delta winding in the primary. So delta / star trformer is used for lighting loads.

Electric traction me using the electric power for traction system (i.e. for railways,trams, trolleys etc).

Electric traction me use of the electricity for railways,trams, trolleys etc. Now a days, magnetic traction is also used for bullet trains.and basically dc motors are used for electric traction systems.

The effect of armature flu to main flux is called armature reaction. The armature flux may support main flux or opposes main flux.

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.

SF6 is Sulpher hexa Flouride gas.. if this gas is used as arc quenching medium in a Circuitbreaker me SF6 CB.

If each block has only one place it can appear in the cache, the cache is said to be direct mapped. The mapping is usually (block-frame address) modulo (number of blocks in cache).

If a block can be placed anywhere in the cache, the cache is said to be fully associative.

If a block can be placed in a restricted set of places in the cache, the cache is said to be set associative. A set is a group of two or more blocks in the cache. A block is first mapped onto a set, and then the block can be placed anywhere within the set. The set is usually chosen by bit selection; that is, (block-frame address) modulo (number of sets in cache). If there are n blocks in a set, the cache placement is called n-way set associative.

Whenever a current carrying conductor is placed in an magnetic field it produce turning or twisting movemnt is called as torque.

A breaker is normally used to break a ciruit. while breaking the circuit, the contact terminals will be separated. At the time of seperation an air gap is formed in between the terminals. Due to existing current flow the air in the gap is ionised and results in the arc. various mediums are used to quench this arc in respective CB’s. but in VCB the medium is vaccum gas. since the air in the CB is having vaccum pressure the arc formation is interrupted. VCB’s can be used upto kv.

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.

An encoder is a device used to change a signal (such as a bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for trmission or storage, encrypting or adding redundancies to the input code, or trlating from one code to another.

This is usually done by me of a programmed algorithm,especially if any part is digital, while most analog encoding is done with analog circuitry.

The following rules distinguish tasks from functions:

  1. A function shall execute in one simulation time unit; a task can contain time-controlling statements.
  2. A function cannot enable a task; a task can enable other tasks or functions.
  3. A function shall have at least one input type argument and shall not have an output or inout type argument;a task can have zero or more arguments of any type.
  4. A function shall return a single value; a task shall not return a value.

Advantages :

  1. Fast Switching Characterstics than Mosfet, BJT, IGBT.
  2. Low cost.
  3. Higher Accurate.

Link is provided at a Neutral common point in the circuit from which various connection are taken for the individual control circuit and so it is given in a link form to withstand high Amps. But in the case of Fuse in the Phase of AC circuit it is designed such that the fuse rating is calculated for the particular circuit (i.e load) only.So if any malfunction happen the fuse connected in the particular control circuit alone will blow off.

  1. ONAN (oil natural,air natural).
  2. ONAF (oil natural,air forced).
  3. OFAF (oil forced,air forced).
  4. ODWF (oil direct,water forced).
  5. OFAN (oil forced,air forced).

If their is high power factor, i.e if the power factor is close to one:

  1. losses in form of heat will be reduced,
  2. cable becomes less bulky and easy to carry, and very cheap to afford, &
  3. it also reduces over heating of tranformers.

uninterrupt power supply is mainly use for short time .me according to ups VA it gives backup.

ups is also two types :

  1. on line.
  2. offline.

online ups having high volt and amp for long time backup with with high dc voltage.but ups start with 2v dc with 7 amp. but inverter is startwith 2v,24,dc to 36v dc and 20amp to 80amp battery with long time backup. 

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.

Bulbs [devices] for AC are designed to operate such that it offers high impedance to AC supply. Normally they have low resistance. When DC supply is applied, due to low resistance, the current through lamp would be so high that it may damage the bulb element.

Synchronous machines have capability to work on different power factor(or say different imaginary pow varying the field emf. Hence syn. generators are used for the production of electricity.

A choke is connected in one end of the tube light and a starter is in series with the circuit. When supply is provided ,the starter will interrupt the supply cycle of AC. Due to the sudden change of supply the chock will generate around 1000volts . This volt will capable of to break the electrons inside the tube to make electron flow. once the current passes through the tube the starter circuit will be out of part. now there is no change of supply causes choke voltage normalized and act as minimize the current.

Power factor should be high in order to get smooth operation of the system.Low power factor me losses will be more.it is the ratio of true power to apparent power. it has to be ideally @if it is too low then cable over heating & equipment overloading will occur.

if it is greater than 1 then load will act as capacitor and starts feeding the source and will cause tripping.(if pf is poor ex: 0.17 to meet actual power load has to draw more current(V constant),result in more losses if pf is good.

ex: 0.95 to meet actual power load has to draw less current(V constant),result in less losses).

When the supply is cutt off for a running motor, it still continue running due to inertia. In order to stop it quickly we place a load(resitor) across the armature winding and the motor should have  maintained continuous field supply. so that back e.m.f voltage is made to apply across the resistor and due to load the motor stops quickly.This type of breaking is called as “Regenerative Breaking”.

In simple, synchronous generator supply’s both active and reactive power but asynchronous generator(induction generator) supply’s only active power and observe reactive power for magnetizing.This type of generators are used in windmills.

Output voltage is greater than the input voltage or receiving end voltage is greater than the sending end voltage.

ACSR me Aluminium conductor steel reinforced, this conductor is used in trmission & distribution.

There are two types of exciters, static exciter and rotory exciter.

purpose of excitor is to supply the excitation dc voltage to the fixed poles of generator.

Rotory excitor is an additional small generator mounted on the shaft of main generator. if it is dc generator, it will supply dc to the rotory poles through slip ring and brushes(conventional alternator).

if it is an ac excitor, out put of ac excitor is rectified by rotating diodes and supply dc to main fixed poles.ac excitor is the ac generator whose field winding are stationary and armature rotates. initial voltage is built up by residual magnetism.It gives the starting torque to the generator.

The shunt connection in four point stater is provided separately form the line where as in three point stater it is connected with line which is the drawback in three point stater.

AVR is an abbreviation for Automatic Voltage Regulator.It is important part in Synchronous Generators, it controls theoutput voltage of the generator by controlling its excitation current. Thus it can control the output Reactive Power of the Generator.

Circuit Breaker is one which makes or breaks the circuit.It has two contacts namely fixed contact & moving contact.under normal condition the moving contact comes in contact with fixed contact thereby forming the closed contact for the flow of current. During abnormal & faulty conditions(when current exceeds the rated value) an arc is produced between the fixed & moving contacts & thereby it forms the open circuitArc is extinguished by the Arc Quenching media like air, oil, vaccum etc

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.

Boucholz relay is a device which is used for the protection of trformer from its internal faults, it is a gas based relay. whenever any internal fault occurs in a trformer, the boucholz relay at once gives a horn for some time, if the trformer is isolated from the circuit then it stop its sound itself other wise it trips the circuit by its own tripping mechanism.

The motor has max load current compare to that of trformer because the motor consumes real power.. and the trformer is only producing the working flux and its not consuming.. hence the load current in the trformer is because of core loss so it is minimum.

Generally capacitor gives infinite resistance to dc components(i.e., block the dc components). it allows the ac components to pass through.

Stepper motor is the electrical machine which act 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.