Electrical Interview Questions and Answers
Q1. What is strength?
Ans: Electricity is a wellknown term used for all phenomena because of electric powered price whether static or in motion.
Q2. What takes place if I connect a capacitor to a generator load?
Ans: Connecting a capacitor throughout a generator always improves power factor, but it'll assist depends up at the engine capability of the alternator, otherwise the alternator could be over loaded due to the greater watts consumed due to the improvement on pf. Secondly, do not connect a capacitor throughout an alternator even as it is picking up or with none other load.
Q3. Define Pole Pitch?
Ans: The distance among the centres of adjoining poles is known as pole pitch. One pole pitch is equals to 180 electric tiers. It is likewise described because the range of slots in keeping with pole.
Q4. What are the kinds of electricity ?
Ans: There are kinds:
Q5. What Is The General System Requirements Of Alternator?
Ans: For the era of emf, there ought to be two simple systems.
Magnetic field gadget to provide the magnetic subject
Armature machine which homes the conductors on which the EMF is to be prompted
Q6. Why the capacitors works on ac only?
Ans: Generally capacitor offers countless resistance to dc components (i.E., block the DC additives). It allows the ac components to skip via.
Pcb layout schooling
Q7. Explain the working fundamental of the circuit breaker?
Ans: Circuit Breaker is one that makes or breaks the circuit. It has two contacts namely constant touch & transferring contact. Under regular condition the shifting touch comes in contact with fixed contact thereby forming the closed contact for the waft of modern-day. During atypical & defective situations (while modern-day exceeds the rated fee) an arc is produced among the fixed & transferring contacts & thereby it forms the open circuit, Arc is extinguished through the Arc Quenching media like air, oil, vacuum and many others.
Q8. What is static energy ?
Ans: Static energy means strength at rest in contradistinction to dynamic or present day energy the effects of that are in basic terms because of the electrostatic discipline produced via the rate. As it's far obtained with the aid of rubbing two substance which include glass and silk it is also referred to as frictional power.
Q9. How many kinds of colling device it transformers?
Ans: ONAN (oil herbal, air natural) 2. ONAF (oil herbal, air pressured) 3. OFAF (oil forced, air compelled) four. ODWF (oil direct, water pressured) five. OFAN (oil compelled, air forced)
Q10. What is the feature of anti-pumping in circuit breaker?
Ans: When breaker is close at one time through close push button, the anti-pumping contactor save you re close the breaker by means of near push button after if it already near.
Q11. Do you realize the benefits of pace controlusing thyristor?
Fast Switching Characterstics than Mosfet, BJT, IGBT
Q12. What Are The Advantages Of Stationary Armature And Rotating Field System?
The desk bound armature coils can be insulated effortlessly.
Higher peripheral velocity can be executed inside the rotor.
Cooling of the winding is extra efficient.
Only two slip jewelry are required to offer DC deliver to the sphere system.
Output current may be effortlessly furnished to the burden circuit. Slip-jewelry and brushes are not important.
Q13. What is contemporary electricity?
Ans: Current electricity manner the energy in movement the outcomes of which can be because of the go with the flow of electrons in a conductor.
Q14. What is stepper motor? What is its makes use of?
Ans: Stepper motor is the electric system which act upon input pulse carried out to it.It's miles one type of synchronous motor which runs in steps in either direction in place of running in complete cycle.So, in automation elements it's far used.
Q15. Name the specific kinds of automobiles used in vacuum cleaners, phonographic appliances, vending machines, fridges, rolling turbines, lathes, energy thing improvement and cranes?
Ans: Following motors are used:
Vacuum cleaners- Universal motor.
Phonographic appliances – Hysteresis motor.
Vending machines – Shaded pole motor.
Refrigerators – Capacitor break up segment automobiles.
Rolling turbines – Cumulative automobiles.
Lathes – DC shunt automobiles.
Power issue improvement – Synchronous motors.
Q16. Will The Alternators Have Rotating Armature System Or Stationary Armature System?
Ans: Generally in alternators, the armature is desk bound and the sector rotates. Small low-voltage alternators regularly have a rotating armature and a desk bound discipline winding.But in big alternators rotating armature field kind is used.
Q17. What are the varieties of contemporary electricity?
Ans: There are types:
Q18. Tell me in element about c.T. And p.T.?
Ans: The time period C.T way modern transformer, and the term P.T means capability transformer. In circuit where measurements of high voltage and excessive present day is worried, they're used there. Electrical Interview Questions & Answers visit www.Eeekenya.Com Page while a measuring tool like voltmeter or ammeter is not capable of measure such high price of quantity due to big value of torque because of such excessive price it could damage the measuring tool.So, CT and PT are added within the circuits. They work on the same principle of transformer, that's based totally on linkage of electromagnetic flux produced with the aid of primary with secondary. They paintings at the ratio to they're designed. E.G. If CT is of ratio 50005A and it has to measure secondary modern-day of 8000A.Then ANS=8000*55000=8Aand this end result could be given to ammeter .And after measuring 8A we can calculate the number one modern. Same is the operation of PT however measuring voltage.
Q19. In the automobiles starting reason why the armature rheostats at most position at the same time as the sphere rheostat is saved in minimum position?
Ans: In the time of starting a motor the sphere rheostat is stored in minimum country for the high starting torque.In the time of beginning a motor the armature rheostats is used to control or lessen the excessive beginning current. This high starting cutting-edge can damage the cars beginning structures.
Q20. What Is Meant By Stator? What Is Meant By Rotor?
Ans: In any electrical gadget ( AC/DC motor or generator) the desk bound member is called as stator. Similarly in all machines the rotating member is called rotor.
Q21. What are the extraordinary techniques of producing power? Give examples.
Ans: The strategies are:
By manner of frictions- Static electricity is produced.
By manner of chemical movement in cells and batteries.
By way of mechanical using- Generator produces energy in two numerous strategies.
By method of heat – Thermal strength is produced.
By means of lighting impact – Electricity is produced in picture electric mobile.
Q22. There are a Transformer and an induction system. Those have the identical supply. For which device the load modern-day can be maximum? And why?
Ans: The motor has max load current evaluate to that of transformer because the motor consumes actual energy and the transformer is handiest generating the operating flux and it’s now not ingesting. Hence the load modern inside the transformer is due to core loss so it's far minimal.
Q23. What's the opposite call for short circuit?
Q24. What Are The Advantages Of Three Phase Motor Over Single Phase Motor?
Ans: Three section vehicles are having:
Higher starting torques.
Improved pace regulation.
Compared to the single phase motors.
Q25.What are the resources of energy?
Q26. What is power factor? Whether it must be high or low? Why?
Ans: Power factor need to be high if you want to get easy operation of the machine. Low electricity thing way losses may be greater.It is the ratio of authentic power to obvious energy. It has to be ideally 1. If it is too low then cable over heating &device overloading will arise. If it's miles greater than 1 then load will act as capacitor and begins feeding the source and will reason tripping. (If pf is bad ex: 0.17 to meet actual strength load has to draw greater cutting-edge (V regular), result in more losses if pf is good ex: zero.95 to meet real electricity load has to draw much less contemporary (V steady), bring about less losses)
Q27. Name electricity losess in rotating electric machines.
Ans: Power losess in rotating electrical machines are Copper losses, center losses, mechanical losses and stray losses.
Q28. What Is Basic Principle Of Operation Of Alternators/dc Generators?
Ans: They are operating at the fundamental precept primarily based on Faraday’s Laws of Electromagnetic Induction.
This law states that, When a modern carrying conductor moves in magnetic area, it induces an EMF.
Q29. What are the packages of electricity?
Ans: Heating, Lighting, Welding, Running of Motors, Battery charging, Electroplating, Relays, telephones, Electronic Equipment, and so on.
Q30. What is the distinction between Isolator and Circuit Breaker?
Ans: Isolator is an off load tool that's used for isolating the downstream circuits from upstream circuits for the reason of any renovation on downstream circuits. It is manually operated and does no longer comprise any solenoid unlike circuit breaker. It ought to not be operated whilst it's far having load. First the load on it have to be made zero and then it is able to properly perform. Its specification simplest rated modern is given. But circuit breaker is on load computerized tool used for breaking the circuit in case of extraordinary conditions like short circuit, overload etc., it's far having three specification 1 is rated modern and 2 is brief circuit breaking potential and three is immediately tripping modern-day.
Q31. What is the importance of vector grouping in Power Transformers?
Ans: Every electricity transformer includes a vector institution indexed by its manufacturer. Fundamentally it tells you the information about how the windings are related (delta or wye) and the phace distinction betweent the contemporary and voltage. EG. DYN11 manner Delta primary, Wye Secondry and the modern-day is at 11 o clock reffered to the voltage.
Q32. How To Minimize The Eddy Current Losses?
Ans: When the center is laminated and insulated from every different with paper or varnish the eddy current loss is minimized.
Q33. What are the outcomes of energy ?
Physiological impact (Electric surprise)
Heating impact (Lamp, Heater, Fuse)
Magnetic effect (Fan, Motor, Electric bell)
Chemical impact (Battery charging and Electroplating)
X – Ray effect ( X- Rays).
Q34. State the factors, for the selection of electrical device for an aero turbine.
Ans: The choice of electrical system for an aero turbine is guided through three factors:
Type of electrical output: dc, variable- frequency ac, and consistent- frequency ac.
Aero turbine rotational velocity: steady velocity with variable blade pitch, almost regular pace with less difficult pitch- converting mechanism or variable velocity with constant pitch blades.
Utilization of electrical strength output: along side battery or different shape of storage, or interconnection with energy grid.
Q35. What Is Meant By Turbo Alternators?
Ans: Turbo alternators are excessive speed alternators. Because of excessive speed of rotation, the rotor diameter is reduced and the axial period is increased. Two or 4 poles are normally used and steam turbines are used as high movers.
Q36. What are A.C. And D.C.?
Ans: A.C is the abbreviation of an alternating modern which flows to and from in a circuit in change path periodically with the version of its value in normal way that after achieving a most in one path decreases to 0, eventually reversing and accomplishing a maximum in the contrary direction decreases to zero once more the cycle of pulsation being repeated continuously. D.C. Is the abbreviation of a direct present day which flows in one path simplest and which does not have any appreciable pulsation in its magnitude.
Q37. What Are The Various Types Of Rotors Used In The Alternators?
Salient pole rotor.
Non- salient pole rotor.