Tag Archives | Electrical Engineering

Phase Comparators and Its Types | Devices | Electrical Engineering

Phase comparison technique is the most widely used technique for all practical directional, distance, differential and carrier relays. In a phase comparator, the operation of the relay takes place when the phase relation between two inputs S1 and S2 var­ies within certain specified limits. Both inputs must exist for an output to occur; ideally, operation is independent of their amplitudes, [...]

By |2018-03-07T08:16:34+05:30March 7, 2018|Comparators|Comments Off on Phase Comparators and Its Types | Devices | Electrical Engineering

Negative Phase Sequence Relay and Its Types | Electrical Engineering

Whenever there is an unbalanced circuit, the unbalanced currents will have a negative phase sequence component. A negative phase sequence (or phase unbalance) relay is essentially provided for the protection of generators and motors against unbalanced loading that may arise due to phase-to-phase faults. Essentially such a relay has a filter circuit which is responsive only to the negative sequence [...]

By |2018-03-07T08:16:34+05:30March 7, 2018|Relays|Comments Off on Negative Phase Sequence Relay and Its Types | Electrical Engineering

Distance Relays and Its Classification | Devices | Electrical Engineering

In this article we will discuss about distance relays and its classification. Introduction to Distance Relays: Distance protection is the name given to the protection, whose action depends upon the distance of the feeding point to the fault. The time of operation of such a protection is a function of the ratio of voltage and current i.e., impedance. This impedance [...]

By |2018-03-07T08:16:34+05:30March 7, 2018|Distance Relays|Comments Off on Distance Relays and Its Classification | Devices | Electrical Engineering

Induction Type Directional Relays | Devices | Electrical Engineering

In this article we will discuss about induction type directional relays used in an electric circuit. Induction Type Directional Power Relay: The non-directional relay can operate for fault flow in either direction. In order to achieve operation for the fault flowing in a specific direction, it is necessary to add a directional element to the non-directional element. The directional (or [...]

By |2018-03-07T08:16:34+05:30March 7, 2018|Induction Relays|Comments Off on Induction Type Directional Relays | Devices | Electrical Engineering

How to Protect Transformers? | Devices | Electrical Engineering

For power transformers, the protection is to be provided usually against dangerous overloads and excessive temperature rise. Dangerous overloads may be due to external faults or the internal ones. External faults, however, are cleared by the relay system outside the transformer within the shortest possible time in order to avoid any danger to the transformer due to these faults. Hence [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Transformer|Comments Off on How to Protect Transformers? | Devices | Electrical Engineering

Differential Protection for Power Transformers | Electrical Engineering

The differential protection used for power transformers is based on Merz-Price circulating current principle. Such protection provides protection against internal phase-to-phase and phase-to-earth faults and is generally used for transformers of rating exceeding 2 MVA. This protection system as applied to power transformers is fundamentally the same as that for generators but with certain complicating features not encountered in the [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Transformer|Comments Off on Differential Protection for Power Transformers | Electrical Engineering

Classification of Circuit Breakers | Devices | Electrical Engineering

There are several methods of classification of circuit breakers. On the basis of type of current they may be classified as ac circuit breakers and dc circuit breakers. AC circuit breakers may be classified on the basis of rated voltages. Circuit breakers below rated voltage of 1,000 V are known as the low-voltage circuit breakers and above 1,000 V are [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Circuit Breakers|Comments Off on Classification of Circuit Breakers | Devices | Electrical Engineering

Circuit Breakers: Operation and Mounting | Devices | Electrical Engineering

In this article we will discuss about operation and mounting of circuit breaker. Operation of Circuit Breaker: Each circuit breaker is provided with an operating mechanism. The functions of this mechanism are: (i) To close the breaker contacts rapidly without hesitation at all currents from zero to rated making current capacity (ii) To hold the breaker contacts together against the [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Circuit Breakers|Comments Off on Circuit Breakers: Operation and Mounting | Devices | Electrical Engineering

Conventional Circuit Breakers: Merits and Demerits | Electrical Engineering

Relative merits and demerits of different types of conventional circuit breakers (bulk-oil circuit breakers, minimum oil circuit breakers and air-blast circuit breakers) are given below: 1. Bulk-Oil Circuit Breakers: Merits: Simplicity in construction, high rupturing capacity, suitability for automatic as well as manual operation; possibility of locating CTs in bushings. Demerits: Larger size and greater weight, fire hazard, explosion hazard, [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Circuit Breakers|Comments Off on Conventional Circuit Breakers: Merits and Demerits | Electrical Engineering

Static Overcurrent Relays and Its Types | Devices | Electrical Engineering

The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. This is because the induction disc characteristics of the overcurrent relays (inverse characteristics) are not amenable to simple mathematical analysis. The first static relays developed were the high speed differential relays and the distance relays. Fault current level detectors are termed overcurrent [...]

By |2018-03-07T08:16:33+05:30March 7, 2018|Static Relays|Comments Off on Static Overcurrent Relays and Its Types | Devices | Electrical Engineering
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