Need for Protection

8/6/2019 Need for Protection

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Protective Relaying


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E volving E lectrical Power System

GENERATOR Light

Heating

Mechanical

Hydro

Thermal

Solar

Wind

Tidal Nuclear

L OAD

L OAD


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M odern Power System..

GENERATION TRANSMISSION DISTRIBUTION

INDUSTRIAL CO MME RCIAL DO ME STIC AGRICULTURAL

U T I L I Z A T I O N


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M ajor Power System

Components..

GENERATION

TRANSFORMATION

TRANS. & DISTRBN.

UTIL IZATION

Generator , Prime M over( Turbine)

Power & Distribution Transformer

Transmission Lines , Cables, Switchgear,Instrument Transformers

M otor, Heater, Appliances


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Protect From

FAU LT F low of very high current through a path not intended for normal current flow

SYSTEM

Voltage CollapseFall of Frequency

Loss of synchronism

InsulationFailure

Lightning Stroke

Over Voltage

M echanical Damage

Human/ Animal Intervention

Thermal Failure

EQUIPMENT

D amage D ue toExcessive Heating

SAFETY

FIRE

EXPLOSION


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Purpose of Protection System

. M inimize damage . Leave unaffected equipment in-service

. M aintain equipment operating limits

. M aintain electrical system stability


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Damages caused

Loss of production Revenue loss Loss of equipment Fire hazard, loss of life Loss of confidence level in using

electricity as a commodity


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Prevention of Fault ?In spite of best design , equipment andsafety standards, faults can not be totallyeliminated

Occurrence of fault can not be predicted

We must prepare for inevitability of faultand try to reduce the damage tominimum


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SYSTEM PROTECTIONSYSTEM PROTECTION

PHIL

OSOPHYPHIL

OSOPHY1 . NEED FOR PROTECTIONNEED FOR PROTECTION2. IMPORTANCE OF EQUIPMENT / L INE2. IMPORTANCE OF EQUIPMENT / L INE

TO BE PROTECTEDTO BE PROTECTED3. FREQUENCY OF ABNORMA L 3. FREQUENCY OF ABNORMA L

CONDITIONSCONDITIONS

4. QUICKNESS OF ISOL

ATION FROM4. QUICKNESS OF ISOL

ATION FROMTHE FAU L TTHE FAU L T

5. COST OF PROTECTION SCHEME5. COST OF PROTECTION SCHEME


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Need for protection

Protection : Preventive control

Precautionary measures to be taken tosafeguard the equipment during abnormalconditions


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Need for protection

Detection of intolerable or unwantedconditions within assigned area.

A form of active insurance designed to maintain a high degree of service

continuity and limit equipment damage.


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Protection M ethodologyContinuously M easureSystem parameters. VIPS

Detect fault bycomparing parameterswith preset value

Isolate fault by breakingcircuit

CT, PT

RE L AY

CIRCUITBREAKER


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Ex tent of ProtectionProviding protection for all abnormalconditions is economically impossible

Protection System should be AD EQ UATE

Adequateness is judged / planned based on:

Rating of protected equipment

L ocation of protected equipment

Importance of continuity of supply

Cost / vitality of the equipment

Probability of abnormal condition


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Types of Protection

PROTECTIONSYSTEM

PRIMARY

BACK-UP

UNIT

NON-UNIT

3

3


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W HAT IS MEANT BYW HAT IS MEANT BY

PROTECTIVE REL

AYINGPROTECTIVE REL

AYINGProtection is a technique to save the costlyProtection is a technique to save the costlyelectrical equipments and lines from damageelectrical equipments and lines from damagedue to faults, in time.due to faults, in time.

Relaying is the process of communication of Relaying is the process of communication of the adverse condition of electricalthe adverse condition of electricalequipments and lines, to the protectiveequipments and lines, to the protective

system.system.

Protective relaying is a team workProtective relaying is a team work


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Primary Backup Protection

Primary relay may fail due to failure of any of thefollowingCurrent or voltage supply to the relays

DC-tripping voltageProtective relaysTripping circuit or breaker mechanismCircuit breaker

Desirable that the backup relaying be arranged suchthat the cause for the failure of primary relay willnot also cause failure of backup relaying.


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PRIMARY PROTECTIONPRIMARY PROTECTION

IT IS THE MAIN SCHEME OFIT IS THE MAIN SCHEME OFPROTECTIONPROTECTION

IN THIS TYPE OF PROTECTION, THEIN THIS TYPE OF PROTECTION, THEDESIGNATED RE L AY W ILL CL EAR THEDESIGNATED RE L AY W ILL CL EAR THEFAU L T W HEN ITS SET VA L UES AREFAU L T W HEN ITS SET VA L UES AREEXCEEDEDEXCEEDED


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BACK UP PROTECTIONBACK UP PROTECTION

THIS TYPE OF PROTECTION TAKESTHIS TYPE OF PROTECTION TAKESOVER W HEN MAIN PROTECTIONOVER W HEN MAIN PROTECTIONFAI L SFAI L S

IT IS A TIMEIT IS A TIME--DE L AYED PROTECTIONDE L AYED PROTECTION


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WHAT ARE THE TYPES OF FAULTS ? WHAT ARE THE TYPES OF FAULTS ?

PHASE FAU L TSPHASE FAU L TS

GROUND OR EARTH FAU L TSGROUND OR EARTH FAU L TS

INTERNA L FAU L TSINTERNA L FAU L TS


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Types of fault

. Phase to phase . Phase to ground . Phase to phase to phase . Phase to phase to phase to ground


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WHAT IS A RELAY ? WHAT IS A RELAY ?

A RE L AY IS AN AUTOMATIC E L ECTRICA L A RE L AY IS AN AUTOMATIC E L ECTRICA L DEVICE THAT CONSTANT L Y MONITORSDEVICE THAT CONSTANT L Y MONITORS

THE CONDITION OF THE EQUIPMENT ORTHE CONDITION OF THE EQUIPMENT ORL INE TO BE PROTECTEDL INE TO BE PROTECTED ..

IT SENSES THE FAU L T AND ACTS.IT SENSES THE FAU L T AND ACTS.

BUT IT CAN NOT PREVENT THEBUT IT CAN NOT PREVENT THEFAU L TFAU L T


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Characteristics of protectiverelaying

Sensitivity -detection of short circuit or abnormal condition

Selectivity - ensure that only theunhealthy part of the systemis disconnected

Speed M inimum fault time &equipment damage Simplicity - M inimum equipment &circuitry


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Characteristics of protectiverelaying

Reliability - to ensure proper action evenafter long periods of inactivityand also after repeatedoperations under severeconditions


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THANKS

Documents

Need for Protection