Saturday, 1 June 2024

High Low Tension Cable Barrier - Vacuum Circuit Breaker - Air Circuit Breakers

TRANSFORMER MAINTENANCE PROCEDURE FOR 3300/440V.

High Tension Cable Barrier - Vacuum Circuit Breaker | Low Tension Cable Barrier -Air Circuit Breakers

Follow The Below Step & Procedure For Compete Maintenance & Testing Of HTCB & LTCB (TOSHIBA MAKE).

1. Get A Work Permit With The Appropriate Tag Number From Operations For The Necessary Transformer.

2. Verify That All Parameters Are Closed On Both The LV And HV Sides. Verify That Both Transformers Are Operational.

3. Create A Work Permit Or Caution Notice And Post It On LV And HV Panels.

4. Turn Off The LV Side ACB And The HV Side ACB Of The Current Tag Number In That Order. Verify That There Isn't A Power Outage.

5. Slide The HT Breaker Panel Open. Pull The Breaker Outward From The Service Position To The Test Position By Lifting The Latch Pins On Both Handles Upward.

6. Turn Off The Control Supply And Take Out The Front Of The "CB" And The Control Connectors. Take Off The Stopper Plate And Pull The VCB Outside The Breaker Box.

7. The LV (ACB) Breaker Panel Is Open.

8. Raise The Flapper (Right-hand Side Of Middle Breaker) And Slide The Rack Out/in Handle Into The Slot.

9. Turn The Handle In An Anticlockwise Direction Until It Reaches The Disconnected Position. After Lifting The Stopper Levers On The ACB's Two Sides, Pull The ACB Outward.

10. Place The Trolley Carrier Inside, Either On Both Sides Of The ACB Or Beneath The Lifting Pins. Raise The Trolley So That It Carries The Breakers. Place The Breaker On The Ground And Pull The Trolley Outside.

11. Use The VCB And ACB Manual On/off Switches To Release The Charged Spring.

12. Position The Earthing Hand Lever Of The Compartment Above The VCB Cubicle On The 3.3 KV Side Earthing Switch.

13. Lift The Earthing Leaver, Slide The Stopper Plate To The Right, And Then Release It.

14. Unscrew The Castle Key From The ACB, Place It In The Earthing Breaker, And Turn It To Release The Clutch.

15. If The Rack-in Handle Reaches The Service Position, Insert It Into The Slot On The Right Side And Spin It Clockwise.

16. Take Off The Handle And Turn On The Earthing Switch's Control Supply.

17. Shut The Panel Door And Activate The Earthing Switch. Take Note Of The Earthing Indicator. Put Barrier Caution Tape With The Appropriate Identification Number On Both Sides Of The Transformer.

18. Wipe Out The Entire Transformer. LV And HV Side Terminal Boxes Should Be Open. Examine And Tighten The Hi-speed Bushings On Terminations.

19. Check And Tighten All Connections To The Soil.

20. Check The Primary And Secondary Windings' Insulation Resistance Both Between The Windings And With Earth. Go With A 2.5kv Megger For HT Winding. To Wind LV, Use A 500v Megger. When Megger, Remove The Neutral Link On The Lt Side.

21. Shut Down The Terminal Units. Verify The Pressure Of Inert Gas. For Testing, Take Some Transformer Oil.

22. Examine, Clean, And Check The ACB And VCB For Abnormalities And Looseness. Put Petroleum Jelly On Your Fingers. Megger Terminal Insulation Resistance Values. Calculate The Poles' Contact Resistance.

23. Examine The VCB And ACB Manual Operations.

24. Place The VCB In The Test Position Within The Breaker Compartment. Adjust The Stopper Flap Back Into Place.

Check To See That The Breakers Are Off, Insert The Control Pin Plugs, And Turn On The Control Supply.

25. Rack Out The LV Side Earthing Breaker To The Unconnected Position. Remove The Key To The Castle.

26. Use The Trolley And Rack To Insert The ACB, Moving The Rack Handle Clockwise To Place It In The Service Position.

27. Use Safety Equipment To Conduct A Functional Test.

28. Move Both Breakers Into The Service Mode. Turn On The HT Breaker. Check The Voltage.

Shut Off The Lt Breaker. Check The Current And Voltage On The HT And Lt Sides.

30. Take Off The Caution Tags And Revoke The License.

31. Record Rack-in And Rack-out Information In The Substation Log Book.

32.  Record All Readings And Values In History Cards.

33.  Send Oil Samples For Testing Acidity And Dielectric Strength.

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Wednesday, 1 May 2024

Switchgear And Substation Testing & Maintenance Procedure

Testing & Maintenance Procedure For Substations And Switchgear.

Overview:             

The Following Procedures Can Be Used To Safely And Effectively Maintain Switchgear And Electrical Equipment.

1. Being Aware Of The Work

2. Making Use Of The Work Permit

3. Getting Ready For The Task

4. Making Use Of The Shutdown

5. Maintenance Tasks

6. Finishing The Work

7. Returning The Power Status To Normal

8. Giving The Permit Back

9. Note The Outcomes.

Comprehending The Work:

The Supervisory Personnel Needs To Be Well Aware Of The Task That Needs To Be Completed In A Methodical And Detailed Manner. Their Subordinates Ought To Have An Equitable Understanding Of This Role.

Maintenance Of 11 K.V./3.3 K.V. Transformers For Substations RM01 To RM13:
  • Verify The Tag Number On The VCB Panel After Receiving The Work Permit.
  • Request With A Copy Of The Work Permit That M-20 Personnel Trip And Earth The Feeder Connected To The 11kv.
  • An Earthing Truck Will Be Used In Lieu Of The Drawn-out 11kv Breaker By M-20 Personnel.
  • Verify That An M20 Employee Has Turned This Earthing Truck "On," Then Secure It With A Lock Of Your Own Choosing And Keep The Key On You.
  • Make Sure There Is No Humming Noise Coming From The Transformer Undergoing Maintenance When You Return To Your Substation.
  • Make Sure The Ycb Panel Is In The Off Position By Checking It Again. This Attests To The Inter-trip With M-20 Feeder's Operational State.
Rack The YCB:

To Access The Test/rack-out Position Of The Breaker, Open The Cubicles, Grasp The Handle And Lift The Latch, Then Exert Enough Force To Bring The Breaker Out. The Latch Will Return To Its Original Position When It Is In The Proper Position.

Disconnect The Control Cable Plugs And Turn Off The Control Supply. Unscrew The Nuts To Remove The Stopper Strip In Front Of The Vcb. By Turning Two Knobs To Release The Handle Hooks, The Draw-out Breaker Is Fully Removed From The Panel.

Earth The Incomer's Cable Side.

Place The Earthing Handle In Its Designated Location, Engage The Latch, And Proceed.

Knowing The Location Of The Equipment, Its Purpose, And Its General Specifications—such As Voltage Level, Capacity, Duty— All Contribute To Identifying The Work.

Before Beginning To Shut Down The Equipment, A Backup Plan Should Be Thought Through And Supplied To Ensure Power Supply Continuity.

Obtaining A Work Permit:

A Work Permit Needs To Be Obtained.

1.1.1. By A Person Who Is Qualified To Accept It.
1.1.2. From An Individual Qualified To Provide It.
1.1.3. For A Legitimately Appointed And Authorized Task.
1.1.4. Following The Operation Staff's Explanation Of The Specific Actions Involved In The Task At Hand.
1.1.5. With The KNPC's Signature And Appropriate Notification.

Engineer Should The Task Need Transferring The Operation Of Any UPS System.
  • Before Beginning Any Task That May Potentially Cause An Announcement Or Alarm To Be Sent To A Department Other Than Operations—for Example, The Fire Station—that Department Should Be Notified About It.
  • The Work Permit Needs To Be Clearly Visible To The Inspecting Authorities Or Easily Accessible At The Location Of The Job.
Putting The Work In Order:

Half Of The Completed And Signed Caution Notice Should Be Placed At The Equipment And The Other Half Should Be Conspicuously Displayed At The Equipment Control Panel Where The Equipment Is Being Used.

Nominations And Notifications For The Maintenance Work Should Be Made To The Staff.

Before Beginning Any Work, At Least Two Senior Supervisor Staff Members Must Identify The Equipment And Verify That It Is In Good Working Order.

Use Warning Tape To Surround And Cordon Off The Appropriate Equipment.

The Individual Permitted To Work Must Have A Thorough Understanding Of The Relationships Between The Equipment That Is Being Maintained And That Which Is Connected To It Through Power Flow Or Process Logic. Seniors Should Be Consulted If There Is Any Uncertainty Until A Suitable Resolution Is Obtained.

Utilizing Shutdown:
Before Beginning Any Work, Ascertain The Current State Of The Power Flow, The Bus Tie's Status, And The Overall Load In The Event That The Transformers Are Operating Simultaneously.

Notify The Operations Personnel (And The Fire Station, If Necessary) Of Your Procedures, As Well As Any Anticipated Alarms And Changes In Power Flow, Right Before You Begin To Shut Down.

After Verifying The Tag Number, Turn Off The Circuit Breaker; This Should Only Be Done By The Authorized Worker With A Valid Work Permit And In The Area Engineer's Presence.

Get The Circuit Breaker Rung Out.

Using The Appropriate Tools And Following The Manufacturer's Instructions, Earth The Circuit.

Upkeep Tasks

Assign The Task To Specific Employees Who Should Only Be Permitted On The Site.

As Directed By The Manufacturer And The Cmms, Do The Necessary Maintenance On The Equipment.

Finalizing Maintenance Tasks.

If There Is Any Cordon Tape Surrounding The Equipment, Remove It.

Clear The Area.

Inform Your Employees That The Work Is Over.

Bringing The System Back To Normal.

After Verifying The Tag Number, Remove The Circuit Earthing In Accordance With The Authorized Process.

Rack-in The Circuit Breaker In Accordance With The Authorized Protocol.

Obtaining A Work Permit Again.

Notify The Operation Crew That The Task Has Been Finished.
Apply Enough Force To Move The Earthing Handle Downward. When The Earthing Switch Is Activated, The Incoming Cable Becomes Earthed.

Observe And Check Correctness Of Indications I.e. VCB Off Condition Earth Switch On Condition.

Secure The Cubbyhole Opening.

Transformer Upkeep.

Assign This Task To A Specific Employee Who Will Only Be Permitted Access To The Transformer Yard.

Starting From The Top And Working Your Way Down, Thoroughly Clean The Transformer's Exterior, Looking For Any Damage Or Leaks Of Oil, Etc.

Lift The Covers Of The Primary And Secondary Side Cable Boxes. Clean Them All And Open The Cover Of The Neutral C.T. Box As Well.

Examine The Connections For Any Looseness Or Spark-pitting, And Tighten Them If Necessary.

Examine, Tidy, And Reinstall All Earthing Connections.

Examine The Silica Gel's Condition And Replace It With The Appropriate Amount Of Oil If Needed.

To Enable Manual Fan Operation, Clean And Inspect The Transformer's Cooling System Control Panel.

As Follows, Megger The Transformer:

1. Turning The Earthing Truck "Off" At M-20 S/S.

2. Turn The 3.3kv Side Earthing Switch "Off."

3. Megger 11 Kv To The Transformer Body, Then Record The Findings.

4. Determine The Main And Secondary Insulation Resistance Values.

5. To Indicate That You Have Finished The Assignment, Sign Column No. 9. Verify That This Signature Appears On Every Copy.

6. Verify That The Operator's Signature Appears On All Three Copies As Proof That The Task Has Been Finished.

7. Remove Your Copy Of The Employment Permit.

Documenting The Outcomes:

1. Enter The Completed Task In The Substation Logbook.
2. Record The Maintenance Work Performed In The History Card File And Sign It.

Use A 5kV Megger For Primary To Earth And Primary To Secondary.

Use A 2.5 KV Megger For Secondary To Earth.

Make Sure There Are No Tools Or Materials Within The Terminal Boxes By Closing Them.

Take Samples Of Transformer Oil To Test For Acidity And Dielectric Strength.

Place The Potential Transformer's Lifting Cart Close To The P.T. Cubicle. Pull Outward After Lifting The Latching Pin On The P.T. Handle On Both Sides. Secure It In The Cart. Take Off The Control Plug Pins. Take It Out And Set It On The Ground.

Tighten The Connection, Clean The P.T. And L.A., And Look For Any Anomalies. Calculate The Values Of Insulating Resistance (2.5 KV Megger).

Rack: Using The Same Process In P.T. And L.A.

Inspect The VCB For Manual Operation, Lubricate All Moving Parts, And Make Sure The Contacts Are Clear. Assess The Poles' Insulation And Contact Resistance.

Set The VCB To The Test Position. Put The Stopper Flap Back Where It Belonged. Turn On The Control Supply And Connect The Control Plug Pins To The VCB.

Conduct Functional Testing.

A) Inter-trip

B) The Trip Alarm For Buchholzs Relay

C) Adjusting Oil Level And Winding Temperature Alarms.

Terminating The Maintenance Project.

1. Take Remove The Tape That Is Cordoning Off The Transformer.

2. Verify That The Hazard Warning Signs In The Transformer Yard Are Posted In The Appropriate Locations.

3. Make Sure The Transformer Yard Is Tidy.

4. Request That Everyone Leave The Transformer Yard And Close It From The Outside.

5. With KNPC Clearance, Calibrate The Measuring And Protective Tools, Then Document The Findings.

6. Inform Everyone Verbally That The Work Is Finished.

Bringing The System Back To Normal

1. Put The Earthing Truck's Key Back And Unlock The M-20 S/S Lock.

2. Ask The M-20 S/S Employees To Take Out The Earthing Truck And Replace The 11 KV VCB In The Service Position.

3. Ask M–20 Employees To Turn The 11 KV Feeders That Are In Question On The VCB.

4. Verify That You Can Hear This Transformer Humming.

5. Verifications From The Panel That The Right Voltage Values Are Available.

6. Turn Off The Transformer's 3.3kv Breaker.

7. Verify The Load That This Transformer Shares With The Other Transformer And The Prior Values.

Obtaining A New Work Permit:

Notify The Operation Crew That The Task Has Been Finished.

At Column No. 9, Indicate That You Have Finished The Assignment. Verify That This Signature Is On All Three Copies.

Verify Sure The Operator's Signature Appears On All Three Copies As Proof That The Task Has Been Finished.

Remove Your Copy Of The Work Permit.

Documenting The Outcomes

Make Notes About The Maintenance Work Completed In The History Card File And Sign It.

Obtain And Review The Results Of The Oil Sample. Add This Outcome To The History File As Well.

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Monday, 1 April 2024

Synchronous Motor Working Principle - Purpose Of A Synchronous Motor

Synchronous Motor Working Principle & Also Purpose Of A Synchronous Motor.

An Electromechanical Device That Transfers Energy From The Electrical To The Mechanical Domain Is An Electrical Motor. We Have Divided The Motors Into Single-phase And Three-phase Categories Based On The Kind Of Input. Synchronous And Induction Motors Are More Frequently Employed Among Three-phase Motors.

An Electrical Field Is Created When Three Phase Electric Conductors Are Arranged In Specific Geometrical Locations (At Specific Angles To One Another). 

At This Point, The Speed At Which The Spinning Magnetic Field Rotates Is Referred To As Its Synchronous Speed. When An Electromagnet Is Placed In A Rotating Magnetic Field, It Becomes Magnetically Locked Into The Field And Rotates At The Same Speed As The Spinning Magnetic Field. 

The Reason Synchronous Motors Are Named Such Is That Its Rotor Rotates At The Same Speed As The Magnetic Field. Because It Only Has One Speed—synchronous Speed—and No Intermediate Speed—that Is, It Is Synchronized With The Supply Frequency—it Can Be Thought Of As A Fixed Speed Motor. 

The Source Of Synchronous Speed Is:-

Primary Characteristics Of Synchronous Motors

Synchronous Motor Construction:

Its Structure Is Essentially The Same As That Of A Three-phase Induction Motor, With The Exception Of The Rotor Receiving A Direct Current Supply—the Rationale For Which Is Provided Later. Let's Now Go Over This Motor Type's Fundamental Construction.

The Following Are The Primary Characteristics Of Synchronous Motors: 

• They Are Not Self-starting By Nature. Before They Are Synchronized, They Need An External Method To Accelerate To Nearly Synchronous Speed.

• Because Their Operating Speed Is Synchronized With The Supply Frequency, They Perform As Constant Speed Motors Under Constant Supply Frequency Conditions, Regardless Of The Load.

• The Ability To Function At Any Power Factor Is One Of This Motor's Special Features. 

Synchronous Motor Operation Principle:

A Synchronous Motor Receives Two Electrical Inputs, Making It A Twice Stimulated Machine. The Rotor Has A Dc Supply, While The Stator Winding, Which Is Made Up Of Three Phase Windings, Is Supplied With A Three Phase Supply. 3 Phase Spinning Magnetic Flux Is Produced By The 3 Phase Stator Winding That Is Carrying 3 Phase Currents. 

An Ongoing Flux Is Also Produced By The Rotor That Holds The Dc Supply. The Above Relation Shows That, Assuming A Frequency Of 50 Hz, The Three-phase Rotating Flux Rotates At A Rate Of Roughly 3000 Revolutions Per Minute Or 50 Revolutions Per Second.

The Rotor And Stator Poles May Be Polarized N-n Or S-S At One Moment, Producing A Repulsive Force On The Rotor, And N-S Providing An Attractive Force The Very Next Instant. 

However, The Rotor's Inertia Prevents It From Rotating In Either Direction In Response To An Attracting Or Repulsive Force, Forcing It To Remain In A Standstill. It Is Therefore Not Self-starting.

In Order To Overcome This Inertia, The Rotor Is First Given A Mechanical Input That Causes It To Rotate In The Same Direction As The Magnetic Field, Approaching Synchronous Speed. After A While, The Synchronous Motor Turns In Time With The Frequency Due To Magnetic Locking.

Starting Techniques For Synchronous Motors:

• Motors That Are Synchronous Are Mechanically Related To One Another. It Might Be A Dc Shunt Motor Or A Three Phase Induction Motor. Initially, Dc Excitation Is Not Provided. After Rotation At A Speed Extremely Near To Its Synchronous Speed, Dc Excitation Is Applied. 

The External Motor's Supply Is Turned Off When Magnetic Locking Occurs After A Certain Amount Of Time.

• Damper Winding: An Extra Winding Is Positioned In The Rotor Pole Face If The Synchronous Motor Is Of The Salient Pole Type. An Induced EMF Is Produced In The Rotor At Its Initial Standstill, When The Relative Speed Between The Damper Winding And The Rotating Air Gap Flux Is Large, Resulting In The Necessary Starting Torque. 

Both Torque And Emf Decrease As Speed Gets Closer To Synchronous Speed, And Torque Also Decreases To Zero When Magnetic Locking Occurs. 

As A Result, In This Instance, Synchronous Is First Operated As An Induction Motor With An Extra Winding Before Being Finally Synchronized With The Frequency.

Use Of Synchronous Motors: 

Synchronous Motors Are Used To Increase Power Factor When There Is No Load Attached To Their Shaft. Because Of Its Ability To Function At Any Power Factor, It Is Utilized In Power Systems When Static Capacitors Are Too Expensive.

• Synchronous Motors Are Used In Situations Requiring Great Power And A Lower Operating Speed (Around 500 Rpm). 

The Equivalent Induction Motor Is Very Expensive, Large, And Heavy For Power Requirements Ranging From 35 Kw To 2500 Kw. Therefore, It Is Preferable To Use These Motors. 

For Example, Rolling Mills, Compressors, And Reciprocating Pumps.

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Friday, 15 March 2024

Types Of Induction Motors | Operating Principle Of Induction Motors

Types Of Induction Motors | Operating Principle Of Induction Motors.

Assembly Or Spare Parts Of An Induction Motor Are Shown In Image Below:


The Most Widely Used Electrical Motor, Known As An Induction Motor, Is Utilized In The Majority Of Applications. Because It Operates At A Speed Lower Than Synchronous Speed, This Motor Is Also Known As An Asynchronous Motor. We Must Specify What Synchronous Speed Is In This. The Frequency And Number Poles Of The Machine Determine The Synchronous Speed, Which Is The Rate At Which The Magnetic Field Rotates In A Rotating Machine.

An Induction Motor Never Reaches Its Synchronous Speed Because The Flux Generated By The Rotating Magnetic Field In The Stator Causes The Rotor To Rotate. However, Because The Rotor's Flux Current Lags Behind That Of The Stator's, The Rotor Will Never Reach The Synchronous Speed Caused By The Rotating Magnetic Field. Single Phase Induction Motors And Three Phase Induction Motors Are The Two Main Types Of Induction Motors That Rely On The Input Supply. 

Three Phase Induction Motors Are Self-starting, Although Single Phase Induction Motors Are Not; We Will Talk About Them Later. Currently, In Order To Get A Machine To Rotate, We Generally Need To Provide Two Supplies, Or Double Stimulation. If We Take A Dc Motor As An Example, We Would Use Brush Arrangement To Provide One Supply To The Rotor And Another To The Stator.

Principle Of Operation Of An Induction Motor: 

One Example Of An Electromechanical Device That Transforms Electrical Energy Into Mechanical Energy Is An Electrical Motor. Three Phase Induction Motors Are The Most Commonly Utilized Motors When Operating In Three Phases Of Ac Power. This Is Because These Motors Are Self-starting, Meaning They Don't Need A Starting Mechanism.

We Need To Be Aware Of The Fundamental Constructional Elements Of This Motor In Order To Comprehend The Three Phase Induction Motor Idea More Fully. There Are Two Main Components To This Motor:

Stator: The Number Of Slots In The Stator Of A Three-phase Induction Motor Is Used To Build A Three-phase Winding Circuit, Which Is Connected To A Three-phase Ac Supply. When Ac Is Applied To The Three Phase Windings, Their Arrangement Inside The Slots Causes Them To Generate A Revolving Magnetic Field.

Rotor: The Cylindrical Laminated Core Of A Three-phase Induction Motor Includes Parallel Slots That Can Hold Conductors. The End Rings Short Circuit The Heavy Copper Or Aluminum Bars That Serve As Conductors And Fit Into Each Slot. The Slots Are Somewhat Skewed Rather Than Perfectly Parallel To The Shaft's Axis Because This Configuration Can Prevent Motor Stalling And Lessen Magnetic Humming Noise.

Operation Of The Three-phase Induction Vehicle
Creation Of A Magnetic Field Rotating:

The Motor's Stator Is Made Up Of Overlapping Windings Spaced 120 Degrees Apart Electrically. A Synchronous Magnetic Field Is Created When The Stator Or Primary Winding Is Linked To A Three-phase Ac Source. This Magnetic Field Rotates At That Speed.

Secrets Associated With The Rotation:

An Electromagnetic Field (EMF) Is Created In Any Circuit By The Rate At Which Magnetic Flux Linkage Changes Along The Circuit, As Stated By Faraday's Law. An Induction Motor Induces An Electromagnetic Field (EMF) In The Rotor Copper Bar When The Rotor Windings Are Closed By An External Resistance Or Directly Shorted By The End Ring, Cutting The Stator Spinning Magnetic Field. 

This Generated EMF Causes A Current To Flow Through The Rotor Conductor.

Here, The Source Of The Electric Current Production Is The Relative Velocity Between The Revolving Flux And The Static Rotor Conductor.

Therefore, In Accordance With Lenz's Law, The Rotor Will Revolve In The Same Direction To Lessen The Cause, Or The Relative Velocity.

Therefore, It Can Be Seen From The Three Phase Induction Motor's Operating Principle That The Rotor Speed Shouldn't Exceed The Synchronous Speed That The Stator Produces. 

If The Speeds Were Equal, There Wouldn't Be Any Relative Velocity, Which Means The Rotor Wouldn't Experience An Electromagnetic Field Induction Or Flow Of Current, Which Would Prevent The Generation Of Torque. 

As A Result, The Rotor Is Unable To Spin At Synchronous Speed. The Term "Slip" Refers To The Variation In Rotor And Stator Speeds (Synchronous Speed). 

An Induction Motor's Rotating Magnetic Field Has The Benefit Of Not Requiring Any Electrical Connections To Be Established To The Rotor.

The Three-phase Induction Motor Is Therefore:

• Autonomous.

• Because There Are No Commutators Or Spark-prone Brushes Present, There Is Less Armature Reaction And Brush Sparking.

• Sturdily Constructed.

• Cost-effective.

• Simpler To Keep Up.

However, We Only Provide One Supply For Induction Motors, So Understanding How They Operate Is Fascinating. It's Fairly Straightforward; The Name Itself Makes It Clear That An Induction Procedure Has Taken Place. Actually, Because Of The Current Flowing Through The Coil, Flux Will Develop When The Stator Winding Receives A Supply.

The Way The Rotor Winding Is Now Configured Causes It To Short Circuit Inside The Rotor. According To Faraday's Law Of Electromagnetic Induction, The Rotor Coil Will Be Cut By The Stator Flux, And Since The Rotor Coils Are Short Circuited, Electric Current Will Begin To Flow In The Rotor Coil. Another Flux Will Be Produced In The Rotor When The Current Flows.

There Are Now Going To Be Two Fluxes: The Rotor Flow And The Stator Flux, With The Rotor Flux Behind The Stator Flux. As A Result, The Rotor Will Experience A Torque That Causes It To Revolve In The Direction Of The Magnetic Flux. Hence, The Rotor's Speed Will Be Determined By The Ac Supply, And It Can Be Adjusted By Changing The Input Supply. Any Kind Of Induction Motor Operates On This Basis.

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Sunday, 10 March 2024

Automatic Control System - Self Operated Controller - Relay Operated Controller

Automatic Control System - Self Operated Controller - Relay Operated Controller.

Automatic Distributor:

It Is A Gadget That Measures A Changeable Amount Or Condition And Acts To Rectify Or Lie Any Deviations From A Chosen Reference That The Measured Value May Have Made.

Automatic System Of Control:

Any Movable Configuration Of One Or More Automated Controllers Working In Closed Loop With One Or More Processes Is Considered It.


Personally Operator Controller:

It Is One In Which The Primary Element Uses The Controlled Medium To Obtain All Of The Energy Required To Run The Final Control Element.

Powered By Relay Controller:

It Is One In Which Energy From Other Sources Is Used To Either Augment Or Magnify The Energy Transferred Through The Primary Element In Order To Operate The Final Control Element.

Methods:

The Collective Work Done In And By The Apparatus Used To Control A Variable Is Referred To As A Process.

Self-control:

It Is A Built-in Feature Of The Procedure That Helps Keep The Controlled Variable's Variation To A Minimum.

Managed Variable:

That Quantity And Condition That Can Be Measured And Controlled Is The Controllable Variable.

Managed Media:

It Is The Material Or Process Energy That Allows For The Control Of A Variable. One Of The Properties Or Conditions Of The Controlled Medium Is The Controlled Variable. For Example, In An Automatic Water Temperature Control System, Temperature Is The Controlled Variable And Water Is The Controlled Medium.

Manipulated Entity:

The Automatic Controller Modifies That Quantity Or Condition In Order To Influence The Controlled Variable's Value.

Oversight Agent:

It Is That Process Energy Or Material, A Condition Or Attribute Of Which Is The Managed Variation. One Of The Control Agent's Attributes Or Conditions Is The Controlled Variable. For Instance, The Manipulated Variable Is Flow, And The Control Agent Is Fuel Gas When A Final Control Element Modifies The Fuel Gas Flow To The Burner.

Starting The Signal:

The Difference Between The Reference Input And A Signal Associated With The Controlled Variable At Any Given Time Is The Actuating Signal. This Is Referred To As An Error Signal.

Deviation: This Is The Difference Between The Controlled Variable's Actual Value And The Value That Corresponds To The Set Point.

Offset:

It Is The Steady State Difference Between The Controlled Variable's Value That Corresponds To The Set Point And The Control Point.

Remedial Action:

It Is The Changed Version Of The Variable That Was Controlled Through The Use Of Controlling Methods. The Final Control Element (Control Value), Which In Turn Modifies The Manipulated Variable, Is Operated By The Controlling Means.

Research Input:

It Serves As An Automatic Controller's Reference Signal.

Set Point:

It Is The Location Where The Mechanism For Establishing The Control Point Is Adjusted.

Center Of Control:

It Is The Controlled Variable's Value That The Automatic Controller Works To Maintain Under Any Given Set Of Conditions.

First Feedback:

To Obtain The Actuating Signal, The Signal Must Be Connected To The Reference Input. To Put It Simply, Main Feedback Is The Difference Between The Actual And Desired Measurements Of The Controlled Variable, Which Results In The Actuating Signal.

Action In Position:

It Is The One Where The Final Control Element's Position And The Controlled Variable's Value Have A Predefined Relationship.

Action Proportional:

It Is The One In Which The Value Of The Controlled Variable's Actual Measurement And Its Value Position Have A Continuous Linear Relationship.

Floating Action:

It Is The One Where The Final Control Element's Speed And Deviation Have A Predefined Relationship.

Derivative Action:

It Is The One In Which The Position Of The Final Control Element And The Time Derivative Of The Controlled Variable Have A Predefined Relationship.

Restaurant Action:

It Is The Movement Of The Value At A Rate Determined By The Size Of The Deviation.

Rate Of Action:

It Is The One In Which The Position Of The Final Control Element And The Rate Of Change Of The Controlled Variable Have A Continuously Linear Relationship. Value Motion Is Produced By Rate Action In Proportion To The Real Measurement's Rate Of Change.

Band Proportional:

It Is The Range Of Values Of The Controlled Variable That Match The Final Control Element's Whole Operational Range.

Rate Of Reset:

It Is The Frequency, Expressed In Minutes, At Which Proportional Speed Floating Action Replicates The Effect Of Proportional Position Action On The Last Control Element.

Reset Action Can Be Expressed In Two Ways:

1. Time Of Reset And 2. Rate Of Reset

1. Reset Rate: This Is Sometimes Stated As The Quantity Of "Repeats" In A Minute. Dividends Are Used To Determine It.
A) Travel Of The Last Control Element (The Value Stroke) In A Minute Due To The Floating Action Of Proportionate Speed.
B) The Journey Resulting From The Identical Deviation In Both Circumstances' Proportionate Position Action.

2. Reset Time: This Is The Amount Of Time That Is Typically Used To Indicate The Rate In Minutes. By Subtracting, It Is Ascertained.

A) The Amount Of Time Needed For The Final Control Element To Move In A Chosen Direction As A Result Of The Combined Effect Of The Proportional Position Plus Rate Action.

B) The Time, Or Alternatively Phrased In Another Manner, Needed For The Same Motion Due To The Influence Of Proportionate Position Action Alone In Both Circumstances With The Same Rate Of Change Of The Controlled Variable. When Comparing Rate Action To Proportional Position Action With The Same Rate Of Change In Actual Measurement In Both Scenarios, It Is The Time Lead In Terms Of Air Pressure On The Control Value Generated.

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Friday, 8 March 2024

What is Switchgear? What Are The Types Of Circuit Breakers?

What is Switchgear? What Are The Types Of Circuit Breakers?
1. What Methods Are Used To Put Out The Arc In An Ac Circuit Breaker?

1) Error With High Resistance.

2) Low Resistance Or Zero Point Interruption Is Put Out Of Commission At The Natural Current Zero Of An Ac Wave And Is Kept From Happening Again By A Quick Accumulation Of The Contact Space's Dielectric Strength.

2. How Do You Define An Anti pump Relay?

A Provision Included Into The Circuit Breaker Or Reclose Scheme That Prevents The Circuit Breaker From Repeatedly Functioning In The Event Of A Permanent Fault If The Closure Impulse Is Longer Than The Protection Relay's And The Circuit Breaker's Working Durations.

3. How Can The Vacuum Level Inside The Vacuum Bottle Be Ensured?

1) Vacuum Gauge
2) By Using A High Voltage, Power Frequency Test.

4. What Crucial Examinations Or OCBs Need To Be Performed During Maintenance?

1) Examine The Insulation Resistance Between Each Pole's Phase And Ground.

2) Examine The Oil's Dielectric Strength And Level. 

3) Examine The Mechanical Processes.

4) Squeaky Insulators.

5) Verify The Terminal For Simultaneous Connections And Contact Length.

6) Calculate The Resistance To Contact.

5. What Kinds Of Circuit Breakers Are There?

A) Miniature Circuit Breakers, Or MCBs.

B) Molded Case Circuit Breakers, Or MCCBs.

D) Oil Circuit Breaker, Or OCB.

D) Minimum Oil Circuit Breaker (MOCB).

F) Air Circuit Breaker, Or ACB.

F) Vacuum Circuit Breaker (VCB).

G) Sulfur Hexa Fluoride Circuit Breaker, Or SF6.

6. How Do You Perform The VCB's Annual Preventative Maintenance?

A) Obtain The Permit.

B) Transfer The Breaker's Load.

C) Turn The Breaker Off And Rack It Out.
 
D) Discharge The Spring Already. 

E) Clean The V.C.B. Physically. 

F) Examine And Clean The Finger Contact.

G) Lubricate The Mechanism After Inspecting It.

H) Rack The Breaker Into The Test Position; 

I) Turn The Breaker On Electrically Three Times For A Trial; 

J) Rack The Breaker Into The Service Position And Provide The Load; 

K) Close The Permit.

7. How Is The Maintenance Of A.C.B. Carried Out?

A) Get A Work Permit; 

B) Shift The Breaker's Load; 

C) Rack Out The Breaker And Release The Spring; 

D) Physically Clean The A.C.B.; 

E) Open The Arc Check; And 

F) Inspect And Clean The Fixed And Movable Contacts.

F) Examine And Clean The Finger Contacts; 

G) Examine And Grease The Mechanism; 

H) Rack The Breaker In The Test Position; 

I) Electrically Turn The Breaker On And Off For Testing; 

J) Rack The Breaker In The Service Position; 

K) Energize The Breaker; 

L) Close The Permit.

8. What Upkeep Is Necessary For Oil Circuit Breakers?

A) Examine Every Component That Supports The Circuit And Take Care Of The Arcing Contact.

B) Check The Oil And Replace It If Necessary.

C) Examine The Insulation For Any Potential Harm.

D) Examine The Tripping And Closing Mechanism.

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Thursday, 7 March 2024

Top Electrical Engineering Interviews Questions With Answer

1. How Does An A.C. Generator Produce Electricity? 

Answer: Prime Mover, Such As A Steam Or Hydro Turbine, Is Required To Provide Mechanical Power Input To The Alternator In Order To Generate Electricity. Due To A Polarity Change In The Rotor Poles (I.e., N-S-N-S), Voltage Is Generated And Has A Sinusoidal Waveform As The Rotor Poles Move Beneath The Armature Conductors That Are Mounted On The Stator.

2. Why Are Over Voltage And Over Current Relays Needed When Voltage Increases And Current Increases As Well? Is It Possible To Measure Over Voltage And Over Current Using Simply Current Measurements?

Answer: No, As Most Loads Are Non-linear In Nature, We Are Unable To Detect An Overvoltage By Merely Monitoring The Current. Rather, The Current Increases Both In The Event Of An Overvoltage And An Under Voltage. 

Thus, Over Voltage And Over Current Protection Are Entirely Distinct From One Another. The Purpose Of An Over Voltage Relay Is To Detect Excessive Voltages And Safeguard The System Against Insulation Failure And Fire. By Detecting Internal Short Circuits, Overload Conditions, And Ground Faults, Overcurrent Relays Help Lower The Danger Of Fire And System Failure. 

3. What Is An Alternator's Power Factor When There Is No Load?

Answer: The Alternator's Synchronous Impedance Is What Causes The Angle Difference When There Is No Load. As A Result, It Ought To Lag Zero Like An Inductor.

4. With A Three-pin Plug And A 220v Ac Rating, 6 Amp. Why Does The Earth Pin's Diameter Differ From The Other Two's? What Is The Aim Of It? 

Answer: Due To The Fact That The Conductor's Diameter And Current Flow Are Inversely Related. Thus, Excessive Currents Are First Avoided In The Earth Link Terminal In The Event That A Short Circuit Occurs In The System. ( Resistance Value Falls As R=PL/A Area Of The Conductor Grows).

5. If We Should Maintain A Consistent Frequency, Then Why Is It Only 50 Hz And 60 Hz And Not Other Frequencies Like 42, 90, 58, 35, Or Anything Else?

Answer: The Frequency Can Be Set To Any Frequency You Choose, But You Will Need To Build Your Own High-voltage Transformers, Motors, And Other Equipment. Because Equipment Is Designed To Function At These Frequencies And The World Maintains A Standard At 50 Hz Or 60 Hz, We Keep The Frequency At 50 Hz Or 60 Hz.

6. Where Is The Tap Attached In A Tap Changing Transformer? Is It On The Primary Or Secondary Side?

Answer: Due To Low Current, Tapes Are Linked To The High Voltage Winding Side. Sparks Will Occur During Tap Changing Operation If We Connect The Tapings To The Low Voltage Side Because Of The High Current.

7. Since A Capacitor Is A Load-free Component, Why Does The Ampere Meter Register Current When The Breakers In The Capacitor Bank Close?

Answer: Active And Reactive Loads Are The Two Types Of Electrical Loads That Are Known To Exist. The Capacitor, Whose Factor Is ISIN, Is A Reactive Load That Is Not Regarded As A Load. Because The Meter Displays The Current RMS Value, Its Design Is Predicated On The Current RMS Value.

8. What Kinds Of Power Are There In Electrical Power?

Answer: When Discussing Electrical Power, Three Different Forms Of Power Are Typically Considered. They're

· Visible Power

· Static Force

· Reactive Energy

9. Why Is A Fuse Placed In The Phase Of An Ac Circuit And A Link Placed In The Neutral?

Answer: The Link Is Delivered In A Link Form To Resist Large Amps And Is Provided At A Neutral Common Point In The Circuit From Which Different Connections Are Obtained For The Separate Control Circuit. However, The Fuse In The Ac Circuit's Phase Is Made In Such A Way That The Fuse Rating Is Solely Determined For That Specific Circuit, Or The Load. Therefore, In The Event Of A Malfunction, The Fuse Associated With That Specific Control Circuit Alone Will Blow.

10. Why Utilize A Voltage Clamp At A High Transmission System? How Come ACB Isn't An Option?

Answer: Since The Die Electric Strengths In VCBS Are Eight Times Greater Than Those Of Air, Vacuums Actually Have Higher ARC Quenching Properties Than Air. That Is Always Air Used In Lt And Vacuum Utilized In HT Breakers.

11. What Kind Of Power Losses Occur In Electrical Machines That Rotate?

Answer: Copper Losses, Core Losses, Mechanical Losses, And Stray Losses Are The Four Types Of Power Losses In Spinning Electrical Machinery.

12. What Distinguishes A Delta-delta Transformer From A Delta-star Transformer?

Answer: Delta-delta Transformer Is Utilized For Voltage Changes At Either The Generating Or Receiving Station; That Is, It Is Typically Used In Situations Where The Voltage Is High And The Current Is Low. A Distribution Transformer Known As A Delta-star Is Utilized To Address Step-down Voltage Problems. Its Neutral Secondary Star Is Employed As The Return Path.

13. What Distinguishes An Alternator From A Generator?

Answer: Two Machines That Transform Mechanical Energy Into Electrical Energy Are The Generator And Alternator. The Structure Of Each Differs, But The Electromagnetic Induction Principle Is The Same In Each. In Contrast To An Alternator, Which Has A Stationary Armature And Rotating Magnetic Field For High Voltages But Uses A Rotating Armature And Stationary Magnetic Field For Low Voltage Output, A Generator Maintains A Stationary Magnetic Field And A Rotating Conductor That Rolls On The Armature With Slip Rings And Brushes Riding Against Each Other. As A Result, It Converts The Induced Emf Into Dc Current For An External Load.

14. Why Are KVA Ratings For Transformers Used? 

Answer: We Just Specify The VA Rating; Power Factor Is Not Taken Into Account Because The Transformer's Power Factor Depends On The Load. Since Power Factor Is Dependent On Motor Construction, Motor Ratings Are Expressed In Kilowatts And Take Power Factor Into Account.

15. What Kind Of Motor Is Used In Trains, What Is The Supply Rating That Is Utilized, And What Is The Working Principle?

Answer: The Trains Have Dc Series To Provide High Starting Torque During Start-up, And The Working Voltage Is 1500 Volts Dc.

16. What Are The Benefits Of Using An Induction Motor With A Star-delta Starter?

Answer: (1) The Lowering Of Current During The Motor's Startup Is The Primary Benefit Of Utilizing A Star Delta Starter. Three To Four Times The Current Of Direct Online Starting Is The Starting Current. (2). As A Result, There Are Less Voltage Drops When The Motor In A System Starts Up And There Is Less Starting Current.

17. What Losses Do Transformers Have?

Answer: Copper Loss And Magnetic Loss Are The Two Main Causes Of Transformer Losses. The Wire's Resistance Is What Leads To Copper Losses (I2R). Hysterics In The Core And Eddy Currents Are The Sources Of Magnetic Losses. After The Coil Has Been Coiled, Copper Loss Is A Constant And May Be Measured. The Hysteretic Loss Is Constant At A Given Voltage And Current. 

However, The Eddy-current Loss Varies Depending On The Frequency That Passes Through The Transformer.

18. What Is Power Factor, Please? Is It Appropriate To Set It High Or Low? Why?

Answer: High Power Factor Is Necessary For The System To Operate Smoothly. There Will Be Greater Losses With A Low Power Factor. It Is The Proportion Of Visible Power To Genuine Power. Ideally, It Must Be 1. 

If It Is Too Low, Equipment Overloading And Cable Overheating Will Happen. If The Value Is Higher Than 1, The Load Will Function As A Capacitor, Supplying The Source And Resulting In Tripping.(If PF Is Low, For Example, 0.17, More Current Must Be Drawn (V Constant) To Satisfy The Real Power Load, Which Increases Losses. 

If PF Is High, For Example, 0.95, Then Less Current (V Constant) Must Be Drawn To Satisfy The Real Power Load, Which Will Reduce Losses.

19. How Many Different Kinds Of Cooling Systems Does It Convert?

Answer: 1. Onan (Natural Oil And Air)

2. Oil Natural, Air Forced, Or ONAF

3. OFAF (Driven By Air And Oil)

4. Direct Oil, Water Pushed, Or ODWF

5. Oil Forced Air Forced (OFAAN)

20. What Distinguishes A Lightning Arrestor From A Surge Arrestor?

Answer: Lightning Arrestor Is Placed Outdoors, Where Lightning Strikes Are Grounded. In Contrast, A Surge Arrestor Is Placed Inside, Where It Consumes Energy And Neutralizes The Effect Of Surges.

21. What Is An AVR, Or Automatic Voltage Regulator?

Answer: Automatic Voltage Regulator Is Shortened To AVR. It Is A Crucial Component Of Synchronous Generators Since It Regulates The Generator's Excitation Current, Which In Turn Regulates The Output Voltage. As A Result, It Has Control Over The Generator's Reactive Power Output.

22. Which Motor — A DC Motor, An Induction Motor, Or A Synchronous Motor — has A Higher Starting Torque And Starting Current?

Answer: The Starting Torque Of Dc Series Motors Is High. The Dc Series Motor Cannot Be Started Without A Load, However The Induction And Synchronous Motors Cannot Be Started While They Are Loaded.

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