power system protection - cdeep engineering...power system protection s.a.soman overcurrent...

Power SystemProtection

S.A.Soman

OvercurrentProtectionPrinciple

DirectionalOvercurrentProtection

DistanceProtectionPrinciple

DifferentialProtectionPrinciple

For TransmissionLines

For Tapped Lines

For Transformers

For Busbars

Summary

Power System Protection

S.A.Soman

Department of Electrical EngineeringIIT Bombay

Power System Protection


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary

Protection Paradigms - Apparatus Protection

1 Overcurrent ProtectionPrincipleDirectional Overcurrent Protection

2 Distance ProtectionPrinciple

3 Differential ProtectionPrincipleFor Transmission LinesFor Tapped LinesFor TransformersFor Busbars

4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Principle of Overcurrent Protection

When the current in a system exceeds a predeterminedvalue, it indicates the presence of a fault.

Relaying decision is based solely on the magnitude ofcurrent.

Used in radial distribution systems.

Overcurrent relaying and fuse protection uses thisprinciple.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Directional Overcurrent Protection

Uses both magnitude of current and phase angleinformation for decision making.

Used in radial distribution systems with source at bothends.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Distance Protection

The basic principle is that the apparent impedanceseen by the relay reduces drastically in case of linefault.If the ratio of apparent impedance to the positivesequence impedance is less than unity, it indicates afault.This protection scheme is inherently directional.Impedance relay and Mho relay use this principle.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary



S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Principle of Differential Protection

It is based on the fact that any fault within an electricalequipment would cause the current entering it to bedifferent from the current leaving it.

By comparing the two currents either in magnitude or inphase or in both, fault can be determined.

It is an attractive option if both the ends of theapparatus are located near each other.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Differential Protection for Transmission Lines

Its implementation requires a communication channel.It is extremely accurate.Its zone is demarkated by CTs.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Differential Protection for Tapped Line


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Differential Protection for TransformerCTs are selected in such a way that under normalconditions the scaled CT currents will match inmagnitude.Under fault condition, differential current will flowthrough the overcurrent relay.Overcurrent relay pick up is set above the no loadcurrent value.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary





4 Summary


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Differential protection for Busbar

If the fault is external the algebraic sum of the currentsentering the bus is zero.

If the fault is on the bus the sum is not zero.


S.A.Soman






For Tapped Lines

For Transformers

For Busbars

Summary


Summary

Basic Principle ofOvercurrent Protection.Directional Overcurrent Protection.Distance Protection.Differential Protection.

Applications of Apparatus Protection.

power system protection - cdeep engineering...power system protection s.a.soman overcurrent...

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