Types of relay pdf

The relay is an automatic protective and switching device which is capable of sensing abnormal conditions in electrical circuits. These are operated to open or close the load contacts in response to one or more electrical quantities like voltage and current. Relay pin configurations. These are some of the different types of relays that are employed in most of the electronic as well as electrical circuits.

The information about the different types of relays serves readers’ purpose and we hope that they will find this basic information very useful.

The following groupings will be used in this technical guide. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Based on operation mechanism protection relay can be categorized as electromagnetic relay , static relay and mechanical.

The contactor in a relay is where the high-power signal is switched. Under normal power system operation, a protective relay remains idle and serves no active function. Electrothermal relay : When two different materials are joined together it forms into a bimetallic strip. When this strip is energized it tends to ben this property is used in such a way that the bending nature makes a connection with the contacts.

A relay is defined as an electrically controlled device that opens and closes electrical contacts, or activates and deactivates operation of other devices in the same or another electrical circuit.

Two types of relay technology are available, mechanical and solid state. The operation of a Normally Closed relay is the same to that of a Normally Open relay , except backwards. FUNDAMENTAL RELAY-OPERATING PRINCIPLES AND CHARACTERISTICS Time delay is obtained in induction-type relays by a drag magnet, which is a permanent magnet arranged so that the relay rotor cuts the flux between the poles of the magnet, as shown in Fig. This p roduces a retarding effect on motion of the rotor in either di rection.

Time-delay relay contacts must be specified not only as either normally open or normally close but whether the delay operates in the direction of closing or in the direction of opening. First we have the normally open, timed-closed (NOTC) contact. Line Protection Transmission lines can be protected by several types of relays, however.

There are different types of polarized relays depends on the magnetic circuit configuration. The two most popular types of these relays include differential and bridge type relays. This is the simplest of the ways to protect a line and therefore widely used.

It owes its application from the fact that in the event of fault the current would increase to a value several times greater than maximum load current. These type of relays are useful in applications where power consumption must be low because they require no current to maintain their position. The directional type is more sensitive to unbalance when the two currents are large, and is less sensitive when they are small.

Balanced beam type relays were used in differential and distance protection schemes. In electromechanical relays, the coil accomplishes this function. A relays Output Circuit is the portion of the relay that switches on the load and performs the same function as the mechanical contacts of electromechanical relays.

Solid-state relays, however, normally have only one output contact.

Also, the design, construction, working, applications, and also relay selection is explained in detail. In this article, the basics of a relay like energized relay and de-energized relay are explained in detail. It is a voltage controlled equipment.

Also, relays are the best way for galvanic insulation between high and low voltage portions of a circuit.