The seminar presentation on substation protection devices outlines the importance of protecting electrical power systems from faults to maintain stability and safety. It details various protection devices such as current transformers, potential transformers, relays, circuit breakers, and lightning arresters, explaining their functions and roles in the protection scheme. The conclusion emphasizes the automation of modern substation protection systems.

1. SEMINAR PRESENTATION
ON
“SUBSTATION PROTECTION DEVICES”
Presented by:
PRINCE KUMAR
ROLLNO- 2021031164
3RD
YEAR (SEC-B)
ELECTRICAL ENGINEERING
MADAN MOHAN MALVIYA UNIVERSITY OF TECHNOLOGY

2. Contents
 Introduction
 Protection devices
 Protection requirement
 Current transformer(CT)
 Potential transformer(PT)
 Relay
 Circuit breaker
 Lightning arrester
 Isolators
 Conclusion

3. Introduction
Substation Protection system
 Power System-Protection is a branch of electrical power
engineering that deals with the protection of electrical power
systems from faults through the isolation of faulty parts.
A typical substation

4. Why Do We Need Protection
 The objective of a protection scheme is to keep the
power system stable by isolating only the
components that are under fault, whilst leaving as
much of the network as possible still in operation.
 Under abnormal working condition protection is
necessary for safety of electrical equipments and
safety of human being.

5. Switchgear And Protection Devices
 What are the Protection devices?
 The apparatus or equipments and their associated
auxiliaries employed for controlling, regulating and
switching on or off the electrical circuits in the
electrical power system is known as “Protection
devices” or “switchgear”.
 Protection devices protect the transmission lines,
generators, transformers and other electrical
equipments from various “faults”.

6. Three-Phase Diagram of the
Protection
CTs
VTs
Relay
CB
Control
Protected
Equipment

7. Components of switchgear
 Current Transformer
 Potential Transformer
 Relays
 Circuit breakers
 Lightning arresters(or “Surge diverter”)
 Isolators(or “Disconnecting switch”)
 Fuse

8. Current Transformer(CT)
 A current transformer (CT) is used for measurement
of alternating electric current.
 When current in a circuit is too high to apply directly to
measuring instruments, a current transformer produces
a reduced current accurately proportional to the current
in the circuit, which can be conveniently connected to
measuring and recording instruments.
 Current transformers are commonly used in metering
and protective relays in the electrical power industry.

9. Current Transformer contd…

10. Potential Transformer(PT)
 Potential transformers (PT) (also called voltage
transformers (VT)) are a parallel connected type of
instrument transformer.
 They are designed to present negligible load to the
supply being measured and have an accurate
voltage ratio and phase relationship to enable
accurate secondary connected metering.
 It gives the reference voltage to the Relay for Over
Voltage or Undervoltage protection.

11. Potential Transformer contd…

12. Introduction To Relay
 A Relay is a logical elements which process the inputs(mostly voltage and
currents) from the system and issue a trip decision if a fault within its
jurisdiction is detected.
 Inputs to the Relays are
 Current from current transformer(CT)
 Voltage from voltage transformer(VT)

13. Circuit Breaker(CB)
 Circuit breakers are an automatically operated electrical devices,
design to close or open contact members, thus closing and
opening an electrical circuit under normal or abnormal
conditions.
 It operates on relays command.
 It handles the large voltage and current.
 A circuit breaker consists of two contacts namely “fixed” and
“moving contacts” which touches each other under normal
condition i.e. when circuit breaker is closed.

14. Circuit breaker contd…
An Oil Circuit Breaker SF6 Circuit Breaker

15. Lightning arrester(Surge Diverter)
 The device or equipment used for the protection of the
power system against voltage surge is called “surge
diverter” or “lightning arrester”.

16. Isolators
 Isolators are used to isolate the high voltage from flow
through line into the bus. It allows only needed voltage
and rest is earth by itself if required.
Isolator

17. Conclusion
 The objective of the protection devices(system) is
to keep the power system stable by isolating only
the components that are under fault, while leaving
as much of the network as possible.
 Now a days the Substation Protection System is
fully automatic.

18. References
 Power system protection and switchgear by Badri
Ram TMH publication.
 Fundamentals of Power system protection by
Yashwant G. Paithankar, S.R. Bhide.
 Electrical Power system by A Wright.
 Wikipedia

19. Thank you...