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Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Power System Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
S.A.Soman
Department of Electrical Engineering
IIT Bombay
Power System Protection
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Electrical Energy is
Generated at few kV and stepped up.
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Transmitted through AC and HVDC lines.
Stepped down and distributed at load centers.
Its natural mode of synchronous operation knits the system
together.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Why do we need protection?
Electrical apparatus operates at various voltage levels and
may be enclosed or placed in open. Under abnormal
operating conditions protection is necessary for
Safety of electrical equipments.
Safety of human personnel.
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Apparatus Protection
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
System Protection
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Types of Protection
Apparatus Protection
Transmission Line Protection
Transformer Protection
Generator Protection
Motor Protection
Busbar Protection
System Protection
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Types of Protection
Apparatus Protection
Transmission Line Protection
Transformer Protection
Generator Protection
Motor Protection
Busbar Protection
System Protection
Out-of-Step Protection
Under-frequency Relays
Islanding Systems
Rate of Change of Frequency Relays
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
What is a Relay?
A relay is a logical element which process the inputs (mostly
voltages and currents) from the system and issues a trip
decision if a fault within its jurisdiction is detected. Inputs to
a relay are
Current from a current transformer.
Voltage from a voltage transformer.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Evolution of Relays
If we zoom into a relay, we can see three different types of
realization:
Electromechanical Relays.
Solid State Relays.
Numerical Relays.
Introduction
Power System
Protection
Electromechanical Relays
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
First generation of
relays.
Uses the principle of
electromechanical
energy conversion.
Immune to
electromagnetic
interference and rugged.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Solid State Relays
These relays were developed with the advent of transistors,
operational amplifiers etc. Their functionality is through
various operations like comparators etc. Their advantages
are
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
More flexible.
Self checking facility.
Less power consumption and low burden.
Improved dynamic perfomance characteristics.
High seismic withstand capacity.
Reduced panel space.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Numerical Relays
Operation of a numerical relay involves analog to digital
conversion of voltage and currents obtained from VT and
CTs. These samples are fed to the microprocessor or DSP
where the protection algorithms process these signals and
necessary decisions are taken.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Its advantages are
Maximum flexibility.
Provides multiple functionality.
Self checking and communication facility.
It can be made adaptive.
Introduction
Power System
Protection
S.A.Soman
1
Overview
Electrical Energy Systems
Types of Protection
2
Relays
Introduction
Evolution of Relays
3
Circuit Breaker
What is a circuit breaker?
4
Summary
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
What is a Circuit Breaker?
A circuit breaker is basically a switch to interrupt the flow of
current.
It opens on relay command.
It has to handle large voltages and currents.
The inductive nature of power system results in arcing
between the terminals of a CB.
CBs are categorized based on the interrupting medium
used.
Introduction
Power System
Protection
S.A.Soman
Overview
Electrical Energy
Systems
Types of Protection
Relays
Introduction
Summary
Necessity of a protection system.
Evolution of Relays
Circuit
Breaker
What is a circuit
breaker?
Summary
Types of Protection.
Three generations of relays.
Role of circuit breakers.