Presented By:-ANIL KUMAR KUMAWAT 4Yr. EE
Guided By:-Mr. GAURAV SRIVASTAVA(Seminar Co-ordinator)
I. Impedance relay
II. Reactance relay
III. Mho relay
designed to trip a circuit breaker when a fault is
A relay may also be called an “electromagnetic
Relays use a “low amperage circuit” to control a
“high amperage circuit”.
Ct & pt
rectifier Measuring unit amplifier Output unitTrip
Consists of level Detector,filters etc.
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
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 :-
o +ve (operative)Torque by
o -ve(restraining)Torque by voltage element
At normal condition
operative torque = restraining torque
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 =
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
Also called NEUMERIC RELAY.
2. Logic processing
3. Parameter setting
4. Event recording
5. Data display
BLOCKS IN NEUMERIC RELAY :-
Induction Type Relays. CircuitManiac.com. Accessed
March 8th, 2012.
Fundamental Relay-Operating Principles and Characteristics.
G.E. Digital Energy. Accessed March 8th, 2012.