1. POWER SYSTEM PROTECTION AND SWITCH GEAR
PRESENTATION ON PROTECTIVE RELAYS
PRESENTED BY:
UTFAL DEBNATH ( ROLL NO-1411030075)
DEBABRATA MAJUMDER(ROLL NO-1411030067)
SUBRATA PAUL(ROLL NO-1411030067)
BE 7th Semester, EE Department
Techno India Agartala
Date of presentation: 07/12/2017
2. CONTENTS
• WHY A SYSTEM NEEDS PROTECTION?
• WHAT IS RELAY?
• OPERATING PRINCIPLES
• TYPES OF RELAYS
• CONCLUSION
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3. WHY A SYSTEM NEEDS PROTECTION?
• There is no fault free system.
• It is neither practical nor economical to make a fault free system.
• Electrical system shall tolerate certain degree of faults.
• Usually faults are caused by breakdown of insulation due to various reasons:
system aging , lightning , etc.
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4. WHAT IS A RELAY?
• Protective relay is a device to trip a circuit breaker when fault is detected.
• Protective relays are electromagnetic devices.
• They need to act quickly to protect circuit, to protect equipment and trip a breaker
within a few thousands of seconds.
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5. OPERATING PRINCIPLES
• They work on the following two main operating principles:
1. Electromagnetic Attraction
2. Electromagnetic Induction
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6. ELECTROMAGNETIC ATTRACTION
• Electromagnetic attraction relays operate by virtue of an armature being attracted
to the poles of an electromagnet being drawn into a solenoid. Such relays may be
actuated by DC or AC quantities.
• Types of electromagnetic attraction relays are:
1. Attracted armature type relay.
2. Solenoid type relay.
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9. INDUCTIONTYPE RELAY
• Electromagnetic induction relays operate on the principle of induction motor and
are widely used for protective relaying purposes involving ac quantities.
• They are not used with dc quantities owing to the principle of operation.
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13. CONCLUSION
• Safety is increased.
• Protective relays are essential for keeping faults in the system isolated and keep
equipment from being damaged.
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