RELAYS

Presented By:-ANIL KUMAR KUMAWAT 4Yr. EE

Guided By:-Mr. GAURAV SRIVASTAVA(Seminar Co-ordinator)

CONTENTS :-Introduction

trip circuit

Functional diagram

Classifications

Distance relAy

I. Impedance relay

II. Reactance relay

III. Mho relay

references

Introduction :-

designed to trip a circuit breaker when a fault is

detected.

A relay may also be called an “electromagnetic

switch”.

Relays use a “low amperage circuit” to control a

“high amperage circuit”.

trip circuit :-

functional diagram:-

Ct & pt

rectifier Measuring unit amplifier Output unitTrip

coil

Dc supply

Consists of level Detector,filters etc.

Classifications :-

According to Construction & Principle –

1. Electromagnetic Attraction relay

2. Electromagnetic Induction relay

3. Electro dynamic relay

4. Moving Coil relay

5. Thermal type relay

6. Static relay etc.

According to Applications :-

1.Under V,Under I,Under P Relay

2.Over V, Over I,Over P Relay

3.Directional or Reverse Current Relay

4.Directional or Reverse Power Relay

5.Differential Relay

6.Distance Relay etc.

According to Time of Operation :-

1.Instantaneous type Relay

2.Definite Time Lag Relay

3.Inverse Time Lag Relay

4.IDMT Lag Relay

Distance relay :-

1.IMPEDANCE RELAY

o +ve (operative)Torque by

current element

o -ve(restraining)Torque by voltage element

At normal condition

operative torque = restraining torque

At fault

operative torque > restraining torque

Also called voltage restrained over current relay.

2.Reactance relay :-

o Operative Torque by current

o Restraining Torque by Current-Voltage Directional relay

+ve torque by over current element

-ve torque by directional unit

Directional element designed for maxi. Torque angle =

90 degree

3.Mho relay :-

Induction cup type structure.

oOperative Torque produced by V & I element.

o Restraining Torque by Voltage element.

Also called Admittance relay.

Digital protective relay

Protective relay that uses a micro

processor to analyze power system

voltages, currents or other process

quantities for the purpose of detection

of faults in an industrial process

system.

Also called NEUMERIC RELAY.

1.Input processing

2. Logic processing

3. Parameter setting

4. Event recording

5. Data display

BLOCKS IN NEUMERIC RELAY :-

REFERENCES :-

https://www.wikipedia.org/

https://books.google.co.in/books?isbn=8184316399

Induction Type Relays. CircuitManiac.com. Accessed

March 8th, 2012.

Fundamental Relay-Operating Principles and Characteristics.

G.E. Digital Energy. Accessed March 8th, 2012.

www.google.co.in