File Name: relay types and working .zip
Facebook Twitter. When the operating current becomes large, the magnetic field produced by an electromagnet is so high that it attracts the armature or plunger, making contact with the trip circuit contacts.
In electrical engineering , a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. Microprocessor-based digital protection relays now emulate the original devices, as well as providing types of protection and supervision impractical with electromechanical relays. Electromechanical relays provide only rudimentary indication of the location and origin of a fault. By combining several functions in one case, numerical relays also save capital cost and maintenance cost over electromechanical relays. Important transmission lines and generators have cubicles dedicated to protection, with many individual electromechanical devices, or one or two microprocessor relays. The theory and application of these protective devices is an important part of the education of a power engineer who specializes in power system protection.
Skip to main content. Search form Search. Introduction of relay pdf. For example, the USB Relay Module can indicate the status by sending signals to an external device such as a buzzer or a light pole. General equation of phase and magnitude comparators, Duality of comparators, Electromagnetic relays, over current relays Directional relays, Distance relay- impedance, Reactance and Mho type, Differential relays.
Both AC and DC relays work on the same principle as that of electromagnetic induction, but the construction is somewhat differentiated and also depends on the.
Definition: The relay is the device that open or closes the contacts to cause the operation of the other electric control. It detects the intolerable or undesirable condition with an assigned area and gives the commands to the circuit breaker to disconnect the affected area. Thus protects the system from damage. It works on the principle of an electromagnetic attraction. When the circuit of the relay senses the fault current, it energises the electromagnetic field which produces the temporary magnetic field.
Relays are electrically operated switches. They are used to control a circuit by a separate low-power signal or to control several circuits with one signal. Relays were first used in long distance telegraph circuits as amplifiers.
As there is no spark in normal working, this hybrid relay is compatible with applications in flammable environment, either in industrial e. Protective relay Wikipedia. Hybrid relays are a combination of the best of both relays with contacts and relays without contacts. Contacts gap Contact gap and opening speed of the contacts have an influence on the length and the duration of the arc. Differential Relay working Function: One of the most important protection in power system is differential protection.
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