Electrical Engineering Interview Question And Answer

Hello everyone, in this article, I will discuss the electrical engineering interview question and answer or some top 100 important points for electrical engineer. If you want an article on some other topics then comment us below in the comment box.

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Also read – Battery Management System Questions And Answers.

Electrical Engineering Interview Question And Answer

1. Best conductor silver > copper > gold > aluminium
2. The best insulator is Diamond.
3. Carbon is a semiconductor.
4. Copper is not present in sufficient quantity on earth so aluminum is used as a conductor.
5. Galium arsenide for Red light from the LED
6. Galium phosphide for Greenlight from the LED
7. In the seven-segment display, 7 LED’s are used
8. Photo-coupler = LED + Photo Diode
9. Diode = uncontrolled rectifier
10. SCR= controlled rectifier
11. In Scr, the gate is controlled element
12. SCR is 4 layer, 3 junctions, 3 terminal device
13. A diode is 2 layer, 1 junction, 2 terminal device
14. P-type semiconductor = trivalent impurity.
15. N-type semiconductor = pants valent impurity
16. Transistor use as an amplifier…
17. In the transistor, the collector has the largest size and base has the smallest size
18. In a transistor, the emitter has maximum dopping and base has minimum dopping
19. Common emitter connection is suitable for amplifier

Important On electrical engineering interview question and answer

1. Dc is more dangerous from AC
2. Frequency of Dc is Zero
3. String Efficiency on dc is 100%
4. Due to skin effect, AC resistance is 1.5 time from dc resistance
5. Skin effect visible on only AC supply
6. Non-uniform distribution of electrons or current in a conductor is called skin effect .. Maximum current at the surface of conductor and minimum at the center
7. For AC calculation RMS values are used
8. For dc calculation all values are used
9. For square wave RMS value = Avg value = maximum value
10. 50Hz frequency used from the point of view of flicker
11. At high frequency, (above 50hz) losses increase
12. At low frequency ( below 50hz) flicker occurs

Basic Electrical Answers

1. Fuse material (lead 37%+ and tin 63%)
2. Soldering material ( lead 60% + tin40%)
3. Fuse wire= high specific resistance and low melting point
4. Switch and fuse always connect in phase
5. Neutral is used as a return conductor
6. Neutral is found by star connection only
7. In star connection :
Line voltage =1.732*phase voltage
And line current = phase current
8. Delta connection :
Line voltage = phase voltage
And line current = 1.732*phase current
9. Star connection used for reducing insulating material and for neutral
10. Colour code method used for resistor & capacitor
11. Carbon is semiconductor material
12. Diamond is the best insulator.
13. Silver is the best conductor ( platinum also.. But not at normal temperature)

Power System

1. Generation voltage =11kv
2. Railway voltage =25k
3. Low voltage =240v & 415volts
4. High voltage = 11 & 33kv
5. Extra high voltage = 66, 132, 220 & 400kv
6. Ultra-high voltage = above 765kv
7. ACSR conductor used to reduce skin effect
8. Hollow and bundle conductor used to reduce corona effect
9. To reduce the Ferranti effect… The reactor used in series
10. Dielectric strength of air 30kv/cm(max)
And 21.1kv/cm(RMS)
11. Air density factor 3.92b/(273+°c)

Electrical Machines Questions And Answers

1. Cogging: when the starting of the induction motor fails called cogging. It’s due to Magnetic locking. To reduced it.
2. Number of rotor slots not equal to stator slots and Rotor slots made skewed
3. Crawling: when induction motor runs at 1/7 the of its rated speed called crawling. It’s due to 7 harmonic.
4. To reduced armature reaction in Dc Machine compensating winding used. It is connected in series with armature winding and which is placed in pole shoes.
5. Dummy coils used for Mechanical balance of rotor and it is not connected with armature winding and no current flows.
6. Commutator in Dc generator acts like a rectifier( AC to dc)
Commutator in Dc motor acts like an inverter ( dc to ac)
7. Color of silica gel in transformer breather :
In fresh condition = light pink
In bad condition = blue
8. Primary voltage per turn = secondary voltage per turn

Synchronous Machine

1. Rotor speed equal to the synchronous speed
2. Two types of rotor :
(a).salient rotor = large dia & small length, suitable for low speed, Used in hydropower plant so call “hydro generator”
(b). Wound rotor = small dia & large length, suitable for high speed ( 3000 & 1500rpm) so-called “” turbogenerator”””, Used in steam, gas and nuclear power plant
3. The normal speed of turbogenerator 3000rpm and normally number of poles is 2
4. The maximum synchronous motor is salient pole motor
5. Alternator and synchronous motor both are double excited Machine
6. Synchronous motor is not self-starting
7. For making synchronous motor self-starting, damper winding used
8. Damper winding also used to reduce Hunting
9. Vibration in the rotor by variable Mechanical input or variable load called Hunting
10. damper winding placed in pole face of the salient pole
11. The asynchronous condenser is an overexcited synchronous motor at No Load
12. Synchronous motor is constant speed motor
13. Mostly AC generator is a synchronous generator
14. Slot harmonics produce in the alternator
15. Full pitch winding ::: pitch factor is 1
16. Short pitch winding ::: pitch factor is less than 1
17. Dc shunt generator is used as exciter in the alternator

Electrical engineering interview question and answer on DC Machine

1. Dc generator rating =KW
2. Dc motor rating =hp
3. Generally the number of poles 4
4. Armature on rotor and field on stator
5. For convert AC into dc armature made on the rotor
6. Commutator works [in Dc generator AC into dc] and [in Dc into AC]
7. Commutator made by hard drown copper
8. Carbon brush
9. In large rating dc generator brush made by copper
10. Infield winding =dc supply
11. In armature winding = AC current
12. Dc series generator used in Dc transmission line as a booster
13. Dc shunt generator =battery charger and exciter in the alternator
14. Dc differential generator = welding
15. Dc cumulative generator = Electro patting
16. Dc series motor = traction, lift, crane
17. Dc shunt motor = boring Machine, drill m/c
18. Dc cumulative motor = coal cutting m/c
19. Dc series motor highest starting torque
20. Dc shunt motor is constant speed motor
21. Dc shunt generator has a constant terminal voltage
22. Dc shunt generator is suitable for parallel operation because it dropping characteristics
23. Normal Efficiency range of dc m/c 80 to 85%

Electrical engineering interview question and answer on induction motor

1. Always works on lagging power factor
2. Air Gap length 0.4 to 4mm
3. Air gap length try to keep minimum as possible for good power factor
4. Synchronous speed = speed of stator flux
5. Slip=(syn speed – rotor speed) / synchronous speed
6. Slip rang 0.1 to 5% no load to full load respectively
7. Slip at the start is 1 or 100%
8. Rotor frequency = slip*supply frequency
9. It is self-starting
10. Power factor at No Load is 0.1 lagging and at full load 0.9 lagging
11. Rotor speed < synchronous speed
12. Slip is positive in IM
13. Synchronous speed= (120*frequency) / poles
14. Maximum synchronous speed 3000 RPM
15. It is a single excited Machine
16. No-load current 30 to 40% of full load current
17. Rotor winding in star connection
18. DOL starter use for up to 5hp
19. Star delta starter for 5 to 20 hp
20. Autotransformer starter for above 20hp
21. Rotating resistance starter use only for sleeping induction motor

Electrical engineering interview question and answer on transformer

1. Static device
2. Higher Efficiency Machine
3. Efficiency range 90 to 98%
4. No-load current is 2-6% of full load current
5. Buchholz relay is the gas-operated relay, used to protect the transformer from INTERNAL FAUT
6. Open Circuit test=>> Iron losses
7. Short Circuit test=>> copper loss at any load
8. Tap changer used for change output voltage at the substation
9. No Mechanical loss in transformer
10. Transformer, alternator, induction motor and dc generator works on Electro Magnetic induction law
11. LV winding wound near at core to save insulation cost
12. Terry winding use to reduced 3rd harmonic
13. Terry winding in delta connection
14. The bushing is made by porcelain
15. Scott connection used for convert 3 phase supply in 2 phase supply
16. Delta star connection used for distribution system
17. In open delta connection capacity is 58% of delta connection
18. The power factor of the transformer and alternator depends on the load.

Important electrical engineering interview question and answer

1. Low resistance R<1 ohm
2. Medium resistance 1<R<100000 ohms
3. High Resistance R>100000 ohms
4. Earth resistance & Armature resistance are low resistance
5. Insulation resistance is high resistance
6. For low resistance Measurement, Kelvin double bridge method used
7. For medium resistance Measurement wheat stone bridge used
8. For high resistance Measurement, megger is used
9. The highest speed of megger is 160 rpm
10. Megger = ohm meter + handicraft permanent magnet dc generator
11. Weine bridge used for frequency Measurement
12. Schering bridge used for capacitance Measurement
13. Heaviside bridge used for mutual Inductance
14. Anderson bridge used for self Inductance of low-quality factory coils Q<1
15. Hay bridge used for self Inductance of high-quality-factor coil s Q>10
16. Maxwell Inductance capacitance bridge used for self Inductance of medium quality factor coils 1<Q<10.

I hope this article may help you all a lot. Thank you for reading. If you have any questions on the electrical engineering interview question and answer, comment below.

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Chetan Shidling

Automotive | Technical Blogger | Engineer | Content Creator

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