Electrical Engineering Guides

Power Systems

Differential Relay

The relays used in power system protection are of different types. Among them differential relay is very commonly used relay for protecting transformers and generators from localised faults. Differential relays are very sensitive to the faults occurred within the zone of protection but they are leas

By Electrical4u 03/26, 2024
Power Systems

Inverse Time Relay | Definite Time Lag Relay

In this type of relays, the time of operation depends upon the magnitude of actuating quantity. If the magnitude of actuating quantity is very high, the relay operation is very fast. In other words, the relay operating time that is time delay in the relay is inversely proportional to the magnitude o

By Electrical4u 03/26, 2024
Power Systems

Instantaneous Relay

In a simple way electrical relay is shown in the figure above. Here the fixed coil is fed from the circuit to be protected. When there is a current in fixed coil above the pick up value, the iron plunger is so attracted, it moves upward and makes NO contact closed. The function of this relay is very

By Electrical4u 03/26, 2024
Power Systems

Distance Relay or Impedance Relay Working Principle Types

There is one type of relay which functions depending upon the distance of fault in the line. More specifically, the relay operates depending upon the impedance between the point of fault and the point where relay is installed. These relays are known as distance relay or impedance relay . Working Pri

By The Electricity Forum 03/26, 2024
Power Systems

Thermal Relay Working Principle Construction of Thermal Overload Relay

The coefficient of expansion is one of the basic properties of any material. Two different metals always have different degree of linear expansion. A bimetallic strip always bends when it heated up, due to this inequality of linear expansion of two different metals. Working Principle of Thermal Rela

By Electrical4u 03/26, 2024
Power Systems

Over Current Relay Working Principle Types

In an over current relay or o/c relay the actuating quantity is only current . There is only one current operated element in the relay, no voltage coil etc. are required to construct this protective relay . Working Principle of Over Current Relay In an over current relay , there would be essentially

By Electrical4u 03/26, 2024
Power Systems

Induction Cup Relay Working Principle Construction and Types

Induction Cup Relay This relay in nothing but one version of induction disc relay. Induction cup relay work in same principle of induction disc relay. The basis construction of this relay is just like four poles or eight pole induction motor . The number of poles in the protective relay depends upon

By Electrical4u 03/26, 2024
Power Systems

Dry Contacts: What is it? (Dry Contact vs Wet Contact, Examples)

What is a Dry Contact? A dry contact (also known as a volt free contact or potential-free contact ) is defined as a contact in which power / voltage is not directly provided from the switch but is instead always being supplied by another source. Dry contacts are known as passive contacts, as no ener

By Electrical4u 03/26, 2024
Power Systems

Latching Relay: What is it? (Circuit Diagram And How it Works)

What is a Latching Relay? A latching relay (also known as a bistable, keep, impulse, stay relay, or simply a “latch”) is defined as a two-positional electromechanical switch. It is an electrically actuated switch used to maintain its position without power applied to the coil. A latching relay is us

By Electrical4u 03/26, 2024
Power Systems

Feeder Protection Relay: A Comprehensive Guide

A feeder protection relay is a device that protects power system feeders from various types of faults, such as short circuits, overloads, ground faults, and broken conductors . A feeder is a transmission or distribution line that carries power from a substation to the load or another substation. Fee

By Electrical4u 03/26, 2024
Power Systems

Trip Circuit Supervision

There are different contacts connected in series along a trip circuit of an electrical circuit breaker . There must be some situation when the circuit breaker should not trip even a faulty current passes through its power contacts. Such situations are low gas pressure in SF 6 circuit breaker , low a

By Electrical4u 03/26, 2024
Power Systems

Motor Thermal Overload Protection

For understanding motor thermal overload protection in induction motor we can discuss the operating principle of three phase induction motor. There is one cylindrical stator and a three phase winding is symmetrically distributed in the inner periphery of the stator. Due to such symmetrical distribut

By Electrical4u 03/26, 2024

Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

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Differential Relay

Inverse Time Relay | Definite Time Lag Relay

Instantaneous Relay

Distance Relay or Impedance Relay Working Principle Types

Thermal Relay Working Principle Construction of Thermal Overload Relay

Over Current Relay Working Principle Types

Induction Cup Relay Working Principle Construction and Types

Dry Contacts: What is it? (Dry Contact vs Wet Contact, Examples)

Latching Relay: What is it? (Circuit Diagram And How it Works)

Feeder Protection Relay: A Comprehensive Guide

Trip Circuit Supervision

Motor Thermal Overload Protection

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