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Difference Between IDMT DT and Instantaneous Relays

Difference between IDMT DT and Instantaneous relays: Generally, the over current relays are differentiating with their time of operation. The most commonly used over current...

Partial Differential Protection | Scheme | Working Principle

What is Partial Differential Protection: Partial differential protection is used to protect the bus bar from over loading, provide the backup protection for main bus...

Vector Surge Relay Working Principle | Main Decoupling Relay | MRN Relay

Vector Surge Relay Working Principle: Vector surge relay is used to protect the transformer/generator/alternator from grid disturbance such as grid failure, grid interruption, vector surge...

Motor Protection Relay MPR Relay Working Principle Higher HP & High Voltage Motor

Motor Protection Relay MPR Relay Working Principle: Motor Protection relays are used to protect the higher HP high voltage induction motor. When we increase the...

Harmonic In Electrical | How Electrical Harmonics Occurs in Power system

What is Harmonic in Electrical: Harmonic in electrical is nothing but an integer multiplication of fundamental frequency. Harmonic are an unwanted distorted waveform which frequency...

Merz Price Differential Protection for Transformer

Merz Price Differential Protection for Transformer: Merz price differential protection is used to protect the transformer from internal short circuit, Internal ground faults and inter...

Single Phase Preventer Working Principle | Induction Motor Protection

Single Phase Preventer Working Principle: Single phase preventer is used to protect the induction motor from single phasing fault. Single phasing is a very dangerous...

Current Based Relay | Voltage Based Relay

Current based relay | Voltage based relay: Current based relay: Current based relay is nothing but an operating element or relay coil is designed to operate...

Phase Reversal Protection | Induction Motor Protection

Phase Reversal Protection | Induction Motor Protection: Phase reversal protection is used to protect the induction motor, from running in reverse direction. Normally running a...

Phase Fault Protection | Induction Motor Protection

Phase Fault Protection | Induction Motor protection Phase fault protection is nothing but an attracted armature type relay unit is connected in each phase current...

ELCB Earth Leakage Circuit Breaker Working Principle

ELCB Earth Leakage Circuit Breaker| Ground Fault Protection on Induction Motor: The ground fault protection is used to protect the induction motor from ground fault...

Difference between Surge Arrester, Lightning Arrester and Lightning Rod

Difference between Surge Arrester, Lightning Arrester and Lightning Rod: Surge arrester is used to protect the circuit or electrical equipment from high voltage transient or...
End fault Protection

End Fault Protection Working Principle

End Fault Protection Working Principle: End Fault Protection is used to protect the busbar from the fault nearer to the sensing device typically current transformer...

Stub Protection Working Function

Stub Protection Working Function: Stub protection is nothing but a simple Phase over current protection which is used to protect the power system under ring...
Capcitive Voltage transformer image

CVT in Electrical Capacitive Voltage Transformer CVT

CVT in Electrical Capacitive Voltage Transformer: CVT Capacitive Voltage Transformer is a step down transformer just like potential transformer which converts high voltage in to...

Check Synchronous Relay Working Principle SKE Relay ANSI Code 25

Check Synchronous Relay Working Principle: Check Synchronous Relay is used to protect the generator from mismatched synchronization. Mismatched synchronous leads to flow heavy circulating current...

SOTF Relay Working Principle – Switch On To Fault protection

Switch on to fault protection (SOTF) Switch on to fault protection (SOTF) is used to provide high-speed tripping when energizing a power line under fault...

Distance Protection Working Principle & Fault Location Detection

Distance Protection Relays Working Principle: In last study we have discussed about only current or voltage based relay. Now we are going to discuss about...

Busbar Protection & Frame Leakage Protection Working Principle

Bus bar Protection: The busbars are an important power distribution part in the power system. They are built inside of the panel with safe condition....

Bus Bar Differential Protection or Circulating Current Protection

Bus bar Differential protection or Circulating Current Protection Bus bar Differential protection or Circulating Current Protection is working under the principle of differential protection. The...

Classification Generator tripping Scheme Class A, Class B & Class C

Classification Generator tripping Scheme Class A, Class B & Class A: The generator Tripping classified according to the fault. Protection of the generator: Voltage Controlled Over...

What is Through Fault

What is Through Faults: Through fault is nothing but a fault which occurs outside of the protective zone or in simple words the external fault...

Plug Setting Multiplier & Time Setting Multiplier

Plug Setting Multiplier & Time setting Multiplier Calculation: Plug setting multiplier is nothing but a ratio between the actual fault current in the relay operating...

Directional Over Current & Non Directional Over Current Protection Working Principle

Directional Over Current & Non Directional Over Current Protection Working Principle: Directional Earth Fault Relay is used to protect the transformer/generator/alternator from over current fault....

Unit Auxiliary Transformer (UAT) Differential Protection 87UAT

Unit Auxiliary Transformer (UAT) Differential Protection: Unit Auxiliary Transformer (UAT) differential protection is used to protect the generator and transformer’s winding internal short circuit, inter...

Rate Of Change Of Frequency (ROCOF) Protection df/dt Working Principle

Rate Of Change Of Frequency (ROCOF) Protection df/dt working Principle: Rate Of Change Of Protection is used for load shedding in situations where sudden loss...

Dead Machine Protection Working Principle – 94G ANSI Code

Dead machine Protection Working Principle -94G ANSI Code Dead machine protection is used to protect the generator or alternator from accidental circuit breaker closing when...

Lockout Relay Working Function 86

Lockout Relay Working Function 86: Lockout relays are nothing but a manual reset relays, which ensure the fault has been cleared or inspected correctly. Lockout...

Rotating Diode Failure Relay Working Principle

Rotating Diode Failure Relay Working Principle? The diode failure relay is used to protect the alternator’s automatic voltage regulator from severe damage against the rotating...

PT Fuse Failure Relay Working Principle VTFF

PT Fuse Failure Relay Working Principle VTFF: PT Fuse Failure Relay VTFF is used to sense the PT fuses healthiness. Generally, In high voltage power...

Generator and Transformer Unit Biased Differential Protection

Generator and Transformer Unit Biased Differential Protection: In a high voltage transmission system, the bus bars are at very high voltages than the generators. The...

Merz Price Differential Protection for Generators

Biased Differential scheme (Merz-Price Scheme) for protection of Generators: This is most commonly used protection scheme for the alternator stator windings. The scheme is also...

Unrestricted Earth Fault Protection Working Priciple

Unrestricted earth fault relay: The unrestricted earth fault protection is used to protect the alternator winding from internal earth fault. It uses a residual connected...

Loss of Excitation Protection Working Principle – 40

Loss of Field or Loss of Excitation Protection: Loss of excitation protection is used to protect the synchronous machine (alternator or generator) acts as induction...

Pole Discrepancy Protection Working Principle – 52 PD

Pole Discrepancy Protection Working Principle: Pole discrepancy protection is used to protect the generator/alternator from single phasing when the circuit breaker is failured to close...
Backup impedance Protection Working Principle (21G)

Backup impedance Protection Working Principle (21G)

Backup impedance Protection Working Principle (21G) The Backup Impedance Protection is used to protect the generator from supplying the over loaded or faulty system and it...
Under frequency protection

Under Frequency Protection Working Principle – 87U

Under Frequency Protection Working Principle: Under Frequency Protection is used to protect the transformer/generator/alternator when the frequency drops below the operating frequency. It is a...
Under Voltage protection

Under Voltage Protection Working Principle 27

Under Voltage Protection Working Principle 27: Under voltage fault protection is used to protect the alternator/generator/transformer winding from low voltage operation. Under voltage protection sense...
Over Voltage protection Working Principle

Over Voltage Protection Working Principle 59

Over Voltage protection 59: Over voltage protection is used to protect the synchronous Generator/transformer/alternator form high voltage. Generally, overvoltage occurs due to sudden load through...
What is Reverse Power protection

Reverse Power Protection Working Principle -32R

Reverse Power Protection Working Principle 32R: Reverse power protection is the most Predominate protection in generator/alternator protection. It is used to protect the alternator/generator from...
Negative sequence relay

Negative Sequence Relay Operation 59_2

Negative Sequence Relay: Negative Sequence Relay is used to protect the alternator/generator from unbalance loading and negative sequence component. The negative sequence current flows in...
stator earth fault relay 59GN 27TN

100% Stator Earth Fault Protection of Generator

100% stator Earth Fault protection: Stator is a stationary winding of generator. It is a heart of the generator. To protect the stator, we have...
Netural overvoltage protection

Neutral Voltage Protection -59GN- 95% stator Earth fault protection

Neutral Voltage Protection -59GN: Neutral Voltage Protection is used to protect the alternator/generator stator winding from stator earth fault. Most commonly, the generator’s neutral point...
Neutral Grounding Transformer

Advantage of Neutral Grounding Transformer NGT

Advantage of Neutral Grounding Transformer NGT? Neutral grounding transformers are a single phase transformer which is used to protect the generator/alternator winding from damaging short...
NGR working on Star Winding

7 Purpose of NGR Neutral Grounding Resistor Transformer & Generator

Why NGR Neutral Grounding Resistor are used. The Short form of NGR is Neutral Grounding Resistor. NGRs are used in an electrical power system to...
Over frequency relay operation

Over Frequency Protection Working Principle -81O

Over Frequency Protection: Over frequency protection or over speed protection is used to protect the generator from over speeding of generator’s rotor, reduce the eddy...
Local Breaker Back Protection LBB 50Z or 50BF

Local Breaker Backup Protection LBB 50Z or 50BF

Local Breaker Backup Protection LBB 50Z or 50BF: Local Breaker Backup Protection is used to protect the generator when the generator’s circuit breaker failed to...
Generator Over Fluxing or Over Excitation Protection

Generator Over Fluxing or Over Excitation Protection 24 G

Over Fluxing or Over Excitation Protection 24 G. Over Fluxing relay is used to protect the generator against overheating and the winding insulation failure. Over...
Pole Slip relay

Pole Slip Protection Out of Step Protection 78PS Working Principle

Pole Slip protection or out of step Protection 78PS: Pole Slip protection: Under normal condition the generator is synchronized with grid. But during some extreme...
Substation relay coordination

What is Relay Coordination

What is relay coordination: The relay co-ordination is nothing but a tripping of protecting relay in a sequence or order in electrical power system. Relay...
Neutral displacement relay operation

Neutral Displacement Relay Operation- 59N

Neutral displacement relay: Neutral Displacement relay is a short form of NDR. Neutral displacement relay is used to protect the transformer against earth fault in...
broken delta Configuration

Open Delta & Broken Delta Configuration

What is Open delta: Two single phase voltage transformer uses in this configuration. The transformer’s one end is connected with the another end of the...
voltage restrained over current relay concept

Voltage Restrained Over Current relay Basic concept -51VR VOC

Voltage restrained Over Current relays: The overcurrent relay is nothing but a relay operates when the current reaches the pickup value. The overcurrent relay is...

Tan-Delta Test – Finding Insulation Ageing Loss Angle Test

Tan Delta Test: Tan Delta testing creates the idea about the insulation ageing or healthiness of the insulation and predict the remaining life of an...

What is The Use Of Knee Point Voltage

Knee point voltage: Knee point voltage is nothing but a magnitude of the saturation limit of the current transformer. Each protection class CT has to...
IDMT over current relay Curve

6 Types of Over Current Relay Used in Power System Protection

Types of Over Current Relay: Over current relay is nothing but a relay element which operates when the current exceeds the pre-set value. The relay...
Contact Multiplier Relay Working Function & Wiring diagram

Contact Multiplier Relay Working Function & Wiring diagram

Contactor Multiplier relay: Contact multiplier relay use or increase the number of contact from any circuits. It just converts single contact into N number of...
Anti-Pumping relay diagram and Working Function Explanation

Anti-Pumping relay diagram and Working Function Explanation

Anti-Pumping relay diagram and Working Function Explanation Already we have discussed about Trip Circuits Supervision relay in earlier. Another two important basic operating relays are...
TCS relay Circuit Digram

Trip Circuit Supervision TCS Relay Working Function and Operation

Trip Circuit Supervision Relay Working Function: Trip circuit supervision relays are used to monitor the trip coil of the circuit breaker. It just checks the...
Restricted Earth fault Protection

Restricted Earth Fault Protection 64R Working Transformer

Restricted Earth Fault Protection: Normally Earth fault is nothing but an unintended contact between the conductor body to ground is called earth fault see here...

Standby Earth Fault Relay Operation 51N

What is Standby Earth Fault Relay: In electrical power system, the fault occurs due to the various factor such as natural disturbance, lightning on the...

Percentage Differential Relay or Biased Differential Protection

Percentage differential relay or Biased Differential Protection: Generally differential protection relay means the relay operates when the phasor difference between the two or more electrical...

Basic Differential Relay Working Function

Differential Relay working Function: One of the most important protection in power system is differential protection. It is used to protect the electrical equipment against...

Difference Between CT and PT Current Transformer & Voltage Transformer

12 Difference Between CT and PT Current Transformer & Voltage Transformer Current transformers are working as a step-up transformer where the voltage transformer works...

IP Enclosure Ratings & Standards Electrical Equipments

IP Enclosure Ratings & Standards Electrical Equipment IP rating is also known as Ingress Protection or International Protection ratings which are defined to the international standard...

Symmetrical Faults & Unsymmetrical Faults

What is Symmetrical Faults and Unsymmetrical Faults During Normal condition, In AC (Alternating Current) power system operates under balanced load conditions. The unbalance condition generally...

What is Sequence Impedance

What is Sequence Impedance: The sequence impedance of the circuit tells about the behavior of the system during any type of asymmetrical fault condition i.e...

Zone of Protection System

Zone of Protection System: All the electrical power system works under zone protection and which can be divided in to several zones of protection. Each...

What is Ground Fault and Earth Fault

What is Ground Fault and Earth fault: Ground fault: Ground Fault is nothing but a fault or contact occurs between the Live conductor to ground/neutral point....