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October 23, 2010

POWER S

YSTEM

Modern Power System Divided In To Three Types:

1.Generation

2.Transmission

3.Distribution

TRANSMISSION INCLUDES

1.C.B & Relay

2.C.T & P.TS

3.Genarator & Motor

4.Feeders & bus bar

5.L.A & Insulators


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October 23, 2010

33KV

400KV AND 132KV

11KV

340V400KV AND 132KV


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October 23, 2010

CURRENT TRANS

FORMER

Operation

Types Of Current Transformer:

1.Ring Core Type2.Split Core Type

3.Wound Primary Type


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October 23, 2010

CIRCUIT BREAK

ER

Function Of C.B

Types Of C.B

1.SF62.Oil Circuit Breaker

3.Air Blast Circuit Breaker

4.Vaccum Circuit Breaker

SF6

1.It Is A Electro Negative Gas

2.Dilectric Strength Is 2 To 3 Times


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October 23, 2010

Capacitor voltage T

ransformers(CVT)

1.CVT2.USAGE OF CVT

3.CVT CONSIST(CVD & EM)

4. CVD

5.EM UNIT

Step Down Extra High Voltage Signal

Provide A Low Voltage Signal


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INSULATORS

USAGE

TYPES OF INSULATORS

1.Pin Type

2.Suspension Type

3.Strain Type

4.Shackle Type


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SHEILD YARD PROTECTION

1.Line Protection

2.Bus-Bar Protection

LINE PROTECTION: Protection Of Lines Is Done With Help Of Distance

Protection

The Five Secondary Cores Used Are

1.Main -1 Dist Protection2.Main -2 Dist Protection

3.Metering

4.Tee Differential -1

5.Tee Differential -2


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MAIN -1 AND 2 DISTPROTECTION

In Addition To Basic Distance Protection This Main 1 & 2 Relay

Is Having Features Such As

1.Auto Reclose Function

2.Check Synchronization3.Over Voltage Protection

4.Under Voltage Protection

5.Over Load Protection

6.Over Current Protection7.Earth Fault Protection


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BUS BAR PROTECTION

1.Frame Leakage Or fault Bus Protection

2.Differential Over Current Protection

3.Voltage Differential Potential


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FRAME LEAKAGEPROTECTION

1.More Favourable To Indoor Substation

2.Doesnt Provide Overlapping Of Protective Zones

Around C.B.

DIFFERENTIAL OVERCURRENT

PROTECTION

1.Based On Simple Circulating Current Principle

2.Applicable To Phase To Phase & Ground Fault


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VOLTAGE DIFFERENTIAL PROTECTION

1.High Speed Protection For Relatively Small Net Voltage

In Differential Circuit.

2.Winding Of CTs Are Connected Together In Series


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MOTOR PROTECTION

VARIOUS TYPES OF MOTOR PROTECTION:

1.Instantaneous Over Current Relay

2.Inverse Definite Minimum Time Relay

3.Defferential Time Over Current Relay

4.Differential Relay


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INSTANTANEOUS OVER CURRENTRELAY

1.Used To Protect Motor From Transient Faults

2.Set Above The Starting Current Of Motor To Avoid

Tripping During Starting Time

INVERSE DEFINITE MINIMUM

TIME RELAY

1.Used To Protect Motor From Over Loads2.Operating Current Setting , Depending Upon The

Fault Current The Time Of Operation Varies


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DIFFERENTIAL TIME OVER CURRENTRELAY

1.Used To Protect Motor From Sustained Over Loads

2.After The Fixed Time Delay, If Current Exceeds

The Set Value It Will Give Alarm Or Trip Command

DIFFERENTIAL RELAY

1.Used To Protect Very Large Motor2.If Any Fault Occur Between The Protected Zone

And Between Two CTs The Relay Will Operate


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TRANSFORMER PROTECTION

VARIOUS TYPES OF TRANSFORMER PROTECTION:

1.Buchholz Protection

2.Frame Leakage Protection

3.Overload Protection

4.Differential Protection

5.Over Fluxing Protection


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BUCHHOLZ PROTECTION

FRAME LEAKAGE PROTECTION

1.Provides Very Sensitive Protection For Oil Filled

Transformers And Reactors

2.Only Suitable For Transformer Fitted With An Oil

Conservator

3.Arguably The Best Overall Transformer Protection

For Internal Faults

1.Provides Earth Fault Protection

2.Frame Of Switch Gear Is Grounded3.When Fault Occur, Fault Leaks From The Frame And

Passes Through The Earth Connection Provided

4.Primary Of The C.T Sense Due To Which Current

Passes Through The Earth Fault Relay, RelayWill O erate


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TRANSFORMER

THESE FAULTS MAY LEAD

TO SERIOUS DAMAGE

INCIPIENT FAULTS

(a)Broken DowncoreBolt Insulations

(b)Shorted

Lamination

(c)Bad contacts

(d)Overheating part

of windingsEARTH FAULT

WINDING SHORT CIRCUIT

THE

PUNCTURE OF BUSHINGS

SHORTCIRCUIT BETWEEN

PHASES

Buchholz relay is being used

in oil & gas operated

transformer .


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OVERLOAD PROTECTION

DIFFERENTIAL PROTECTION

1.Used For Large Transformer Fitted With Oil And

Winding Temperature Indicator

2.If Gas Is Mainly Hydrogen With Less Than 2% CO

Then Fault Is Likely Involve Only Insulation Oil

3.If Gas Is Mainly Hydrogen With About 20% CO Then

Fault Is Concerned With Both Solid And Oil Insulation

1.Used To Protect Large Transformer Only

2.CTS Are Selected In Such A Way That UnderNormalCondition The Scaled CT Current Will Match

3.Under Fault Condition Different Current Flow Through

The Over current Relay

4.Over Current Relay Pickup Is Set Above No Load

Current Value


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OVER FLUXING PROTECTION

1.Caused Generally By Too High Voltage Or Too Low

Frequency

2.May Cause Magnetizing Current To Increase To

Unacceptable Level/Duration3.Generally Provided In Modern Biased Differential

Relay


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CONCLUSION

In A Substations, The Prime Job Of An Electrical

Engineer Is To Protect The Electrical System Against The

Various Faults And Thus Avoid Malfunctioning Of the

System . The System Faces Faults Due To OverloadingOverheating , Working At Lower Voltages And Low

Frequency . The Losses And Damage To Which The

Machines Are Subjected To While Working Under Abnormal

Condition Are Huge. Thus, To Reduce The Losses, The

Electrical System Has To Be Protected Against The Faults.


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protection of transmission network

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