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Tuesday, 5 March 2024

Top 15 Question Ask In Interviews For Electrical Engineer

1. What Is A Vacuum Circuit Breaker? What Is Its Purpose? Where Is It Used?

Answer: To Break A Circuit, A Breaker Is Typically Utilized. Separating The Contact Terminals Is What Will Happen When The Circuit Is Broken. Between The Terminals, An Air Gap Forms At The Moment Of Separation. The Arc Is Caused By The Ionization Of The Air In The Gap Caused By The Current Flow. This Arc Is Quenched In The Appropriate CBS Using A Variety Of Media. However, Vacuum Gas Is The Medium In VCB. The Arc Creation Is Stopped Because Of The Vacuum Pressure In The CB's Air. Up To 11 KV Can Be Used With VCB's.

2. What Does An SF6 Circuit Breaker Mean?

Answer: Sulfur Hexa Fluoride Gas, Or SF6 For Short, Is Utilized In Circuit Breakers As An Arc Quenching Medium (SF6 CB).

3. What Distinguishes MCB From MCCB, And In What Situations May It Be Applied?

Answer: Micro Circuit Breaker (MCB) Is A Thermally Driven Device Used In Circuits With Small Current Ratings To Prevent Short Circuits. MCCB Circuit Breakers Have Molded Cases And Are Magnetically Operated For Instantaneous Trip In The Event Of A Short Circuit And Thermally Operated For Over Load Current. Under Frequency And Under Voltage Could Be Built-in. When The Average Current Exceeds 100a, It Is Typically Used.

4. What Role Does The Lockout Relay Have In The HT Voltage?

Answer: Lock-out Relay Is Often Positioned Either In Front Of Or Behind The E-stop Switch To Enable Centralized Power Outages. This Relay Is Controlled By A Key Lock Switch And Draws Power From The Same Electrical Source As The Control Power. Up To 24 Contact Points Can Be Found Inside The Relay Itself. This Enables The Control Power To Be Locked Out Of Several Machines With A Single Key Switch.

5. What Is A Relay With Reverse Power?

Answer: The Protection Of The Generating Station Is Provided By Reverse Power Flow Relays. A Generating Station Is Meant To Supply Electricity To The Grid; However, If The Generating Units Are Not Operating And The Plant Is Not Producing Any Energy, The Plant May Draw Electricity From The Grid. Reverse Power Relays Are Used To Cut Off The Generator's Power Supply From The Grid.

5. What Distinguishes A Fuse From A Breaker?

Answer: When There Is An Excessive Current Flow In The Circuit, Fused Connections Burn, But Breakers Simply Remain Open And Do Not Catch Fire. Breakers Are Used Numerous Times, Whereas Fuses Are Only Used Once.

6. What Is The Connection And Operation Of A Tube Light Circuit?

Answer: Starter Is Connected In Series With The Circuit And A Choke Is Attached To One End Of The Tube Light. The Starter Will Stop The Ac Supply Cycle When The Supply Is Given. Owing To The Abrupt Shift In Power, The Chock Will Produce Around 1000 Volts. In Order To Create An Electron Flow, This Voltage Must Be Able To Break The Electrons Inside The Tube. The Starter Circuit Will Be Out Of Part After The Current Flows Through The Tube. Since The Supply Has Not Changed, The Choke Voltage Has Normalized And Is Acting To Reduce Current.

7. Why Do Birds Not Get Shocked When They Perch On Electricity Or Transmission Wires?

Answer: It Is True That Birds Do Not Receive An Electrical Shock If They Contact The Phase Or Neutral Line. Birds Experience Electrical Shocks When They Come Into Contact With Two Lines, Which Closes The Circuit. Therefore, If A Person Touches A Single Line While In The Air (Not Touching) Or While Standing On The Ground, They Will Not Be Shocked; However, If They Stand On The Ground And Touch A Line, They Will Be Shocked Because Most Electric Lines Have Grounded Neutral. This Indicates That A Person Touching The Line Closes The Phase-to-neutral Circuit.

8. What Kind Of Air Conditioning Motor Is Utilized In Fans Found In Homes, Such As Exhaust Fans, Pedestal Fans, Bracket Fans, And Ceiling Fans?

Answer: It Is A Single-phase Induction Motor With A Squirrel Cage Rotor That Is Started And Run By Capacitors.

9. What Is The Function Of An Exciter?

Answer: Static Exciters And Rotational Exciters Are The Two Types Of Exciters. The Exciter's Function Is To Provide The Generator's Fixed Poles With An Excitation Dc Voltage. A Second Tiny Generator Installed On The Main Generator's Shaft Is Called A Rotary Exciter. If The Generator Is Dc, It Will Use A Slip Ring And Brushes To Provide Dc Power To The Rotating Poles (Traditional Alternator). If The Exciter Is Ac, Its Output Is Rectified By Turning Diodes, Which Then Supplies Dc To The Main Fixed Poles. The Ac Generator Known As An Ac Exciter Has An Armature That Rotates And Stationary Field Windings. Remaining Magnetism Builds Up The Initial Voltage. It Provides The Generator With Its Starting Torque.

10. What Would Happen If We Attached A Capacitor To The Load Of A Generator?

Answer: Adding A Capacitor To A Generator Always Raises Its Power Factor, But How Much Of An Improvement It Makes Relies On The Alternator's Engine Capacity. If It Isn't, The Extra Watts That The Increased Power Factor Causes The Alternator To Consume Will Overload It. Second, Avoid Connecting A Capacitor Across An Alternator When It Is Not Receiving Any Other Load Or When It Is Picking Up Power.

11. What Is The Circuit Breaker's Operating Principle, Please?

Answer: Circuit Breaker Is A Device That Can Create Or Break A Circuit. There Are Two Types Of Contacts On It: Movable And Fixed. Under Typical Circumstances, The Moving And Stationary Contacts Come Into Contact To Establish The Closed Contact Necessary For Current Flow. An Arc Is Created Between The Fixed And Moving Contacts When Abnormal Or Malfunctioning Conditions (When Current Exceeds The Rated Value) Occur, And This Creates An Open Circuit. Arc Is Extinguished By Media That Quench Arc, Such As Vacuum, Oil, And Air.

12. What Are PT And CT? Where Is It Applied?

Answer: A Potential Transformer Is Referred To As A P.T. And A Current Transformer As A C.T. They Are Employed In Circuits Where Measurements Of High Voltage And High Current Are Involved. In Particular, A Measuring Equipment Such As A Voltmeter Or Ammeter May Become Damaged If It Is Unable To Measure A High Number Due To A Big Torque Value. Thus, The Circuits Introduce Ct And Pt. Their Operation Is Based On The Same Transformer Principle, Which Links The Electromagnetic Flux Generated By The Primary And Secondary. They Operate According To Their Design Ratio.

E.g: If CT’s Of Ratio 5000\5A And It Has To Measure Secondary Current Of 8000A.

Then Ans=8000*5\5000=8A and This Result Will Be Given To Ammeter And After Measuring 8A We Can Calculate The Primary Current. 

Same System Of The Operation Followed In  Pt But It Is For Measuring Voltage.

13. What Does The Term "Insulation Voltage" In Cables Mean? Describe It.

Answer: Cable's Ability To Sustain An Applied Voltage Without Breaking Is Referred To As Its Insulation Level.

14. In Distribution Lines, Where Should The Lighting Arrestor Be Installed?

Answer: Next To Substation Power Transformers, Distribution Transformers, And 11 KV Outgoing And 33 KV Incoming Feeders.

15. Why Do Lighting Loads Employ Delta Star Transformers?

ANSWER: Because Lighting Loads Require A Neutral Conductor, A Star-wound Secondary Is Required.in All Three Phases, There Is Always An Imbalance In The Illumination Load. We Use Delta Winding In The Primary In Order To Reduce Current Imbalance. For Lighting Loads, A Delta/star Transformer Is Therefore Utilized.

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