Single throw st normally open no the circuit is connected when the relay is active and. Poles means the number of input circuit power circuit. I believe the types of relays are classified according applications and how they are triggered or controlled electromagnetics are controlled by a coil actuated contacts, and depending on the. Activating the contact unit using electromagnetic attraction, which is produced when electric current exceeding the specified value flows to the electromagnet. Overview learn about switch basics, including the pole and throws naming convention, normally open no and normally closed nc terminology, different switch topologies, and types of switches such as electromechanical.
These classifications include electromagnetic, solid state, high voltage, thermal relays, and so on. Because the parts are not moving while the relay is in action, it can be considered very durable in comparison to other relay types. Philosophy of protection, nature, causes and consequences of faults, zone of protection, requirements of a. With hinged relays, the armature of the electromagnet rotates around a fulcrum. Typical relay contains electromagnetic coil, no contact, nc contact and common contact, electromagnetic coil accepts low voltage dc bias and becomes electromagnet to attract the. Now lets have a look on which different protective relays are used in different power system equipment protection schemes. Mechanical switch is a switch in which two metal plates touch each other to make a physical contact for the current to flow and separate from each other to interrupt the flow of. Relays are classified into the following types, depending on whether. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Activating the contact unit using electromagnetic attraction, which is produced when electric current exceeding the specified. The relay may be less expensive than other types, but this is partly offset by the increased costs in the external circuit.
From standard solutions to custom designs, we offer reliable, costeffective products for mechanical, electrical, digital, analog, miniature, and harsh environment. Relay is also a switch that connects or disconnects two circuits. A relay comprises of an electromagnet and a contact unit. Under normal power system operation, a protective relay remains idle and serves no active function. Different types of relays power system protection youtube.
Protective relays work in concert with sensing and control devices to accomplish their function. By doug wifb hat could be more ordinary than a switch. Based on the number of poles and throws, switches are classified into following types. The contactor switch also has a voltage and current rating that tells you how much power you can expect the relay to conduct before. In another type, a ratchet relay has a ratchet mechanism that holds the contacts closed after the coil is momentarily energized. But instead of manual operation a relay is applied with electrical signal, which in turn connects or disconnects another circuit. When the relay is deactivated, the circuit connects.
Electrical switches not require physical or manual contact, it has ability to perform operation. Jun 08, 2019 types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Mechanical switches further classify into different types of switches based on number of poles and throughs. Mechanical switch is a switch in which two metal plates touch each other to make a physical contact for the current to flow and separate from each other to interrupt the flow of current.
The world of switches and relays american radio relay. Latching relays are the same as the singleside stable relays described previously except that the core, yoke, and armature are made from semihard magnetic material and there are at least two coils in the relay. Different types of switches with circuits and applications. In the simplest case, most circuits contain an onoff switch. Though it may seem strange to cover the elementary topic of electrical switches at such a late stage in this book series, i do so because the chapters that follow explore an older realm of digital technology based on mechanical switch contacts rather than solidstate gate circuits, and a thorough understanding of switch types is necessary for. A single throw relay can control only one circuit i. Types of relays the relay may be defined as an electrical device interposed between the main circuit and the circuit breaker in such a manner that any abnormality in the circuit acts on the relay, which in turn if. A switch is an electrical component that can make or break an electrical current. An example of an ideal relay application is having one electrical signal setup to control several circuits, allowing complete isolation of electricity between the controller and the controlled circuits.
A polarity controlled relay needs changeover switches or an h bridge drive circuit to control it. Different types of switches network switches eeweb community. The switch is an electrical device that is used to break or make an electrical circuit manually or automatically. A mechanical relay is essentially a combination of. A relay is an electromagnetic switch that is used to turn on and turn off a circuit by a low power signal, or where several circuits. Many of nkks switches are recognized or certified by ul, culus, and csa. Different types of electrical switches and light switch types. Different types of switches network switches eeweb. Switches are generally used to close or open the circuit manually. Dictionary says that relay means the act of passing something from one thing to another, the same meaning can be applied to this device because the signal received from one side of the device controls the. Electrical switches types electrical relay switches. The contactor switch also has a voltage and current rating that tells you how much power you can expect the relay to conduct before the contacts fail. There are many different types of relays used in todays world of electronics, and the properties of each determine what type of relay is used in which device. Under normal power system operation, a protective relay.
Hybrid relays are a combination of the best of both relays with contacts and relays without contacts. The term static implies that the relay has no moving mechanical parts in it. Actually, a relay is nothing but a combination of one or more open or closed contacts. Electrical switches operate under the action of semiconductors.
Hinged relays switch contacts by the rotating movement of an armature around. Various electrical or electronic circuits use switches to control or trigger the owl circuit. Relays are like remote control switches and are used in many applications telephone exchanges, digital computers, and automation systems because of their relative simplicity, long life, and proven high reliabil. As relay diagrams show, when a relay contact is normally open no, there is an open contact when the relay is not energized. Switches are mechanical devices with two or more leads or terminals that are. The control circuit has a small control coil while the load circuit has a switch. Activating the contact unit using electromagnetic attraction, which is produced when. Other standards 9ul94v0 rating on several switch lines 9tv rating tv5, tv8 for jw rocker series vde approved models include jp, jw, p, sw3006a, and wr. Relay seminar report with ppt and pdf free download. The world of switches and relays american radio relay league. The relay may be less expensive than other types, but this is partly offset by the increased costs in the external. The current flowing in one circuit causes the opening or closing of another circuit. Compared to the electromechanical relay, the solid static relay has longer lifespan, decreased noise when operates and faster respond speed.
Relays are switches that open and close circuits electromechanically or electronically. Most of the switches are designed have one, two or three poles and are designated as single pole, double pole and triple pole. In simple english, a switch is an electronic device which is used to break or. Protective relaying is a team work of ct, pt, protective relays, time delay relays, trip circuits, circuit breakers etc. Special types are used, for example, for control of machinery, to reverse electric motors, or to sense liquid level. These are similar to the electromechanical relays but there exists both permanent magnet and electromagnet in it, the movement of the armature depends on the polarity of the input signal applied to the coil. Mechanical switches can be divided into two basic types. Switches are an important part of most electronic circuits. They are achieved by setting a simple network management protocol or snmp. Managed switches can be customized to enhance the functionality of a certain network. Two types of managed switches include smart switches and enterprise managed switches. Different types of electrical relay switches are available in market.
The first, commercial and appliance switches, are used in fairly clean environments such as offices or homes. It can be activated many times without fail as opposed to. Electrical switches are binary devices, they can be. This book contains a description of electrical relays, their principles of operation, and. Operating state set when current flows through coil a, the electromagnet made of. Types of relaysoverload protection relay,solid state. A relay is a switch that is turned on or off using electricity.
Types of relays relays are available with several different operation types depending on your application, so it is useful. Here we shall consider plungertype and attractedarmaturetype ac or dc relays that are actuated from either a single current or voltage source. Relays are remote control electrical switches that are controlled by another switch. Technical explanation for generalpurpose relays omron. There is no electrical connection inside the relay between. Switches can be simple onoff types or can have multiple positions that, for instance, can control the speed of a multispeed fan. An electrical switch which uses an electromagnet to move a switch from off position to on position instead of using a person to move. Iso micro relay types below are two popular micro iso relay configurations. Relays are the control switches that operate with lowpowered electrical signals controlling most types of circuits.
Know about different types of switches and their applications. Dictionary says that relay means the act of passing. Switchgear and protective devices 310 modulei 10 hours protective devices. Unit i introduction of relays a relay comprises of an electromagnet and a contact unit. What is relay switch relay operation, working and testing. The contactor in a relay is where the highpower signal is switched. The relay is an automatic protective and switching device which is capable of sensing abnormal conditions in electrical circuits. The working principle of switch depends on on off mechanism. The main difference between relay and switch is that the relay is a. Relays are classified into several types based on their functionality and application they are implemented for. Shop electromechanical relay switches at automationdirect.
Polarized relays use the magnetic flux of the permanent magnet in. List different protective relays are used for different power system equipment protection. The types of switches depend on the connections of the circuit they make. These relays are used in applications where there is a need to limit power dissipation and consumption. Latching relays are the same as the singleside stable relays described previously except that the core, yoke, and armature are made from semihard. A relay is an electromechanical device that is actuated by an electrical current. Relays control one electrical circuit by opening and closing contacts in another circuit. Changeover co doublethrow dt contacts this type of contacts are used to control two types of circuits. Relays allow one circuit to switch over to a second circuit that can be completely separated from the first. There are many different types of electrical switches. Mar 27, 2018 relay seminar report with ppt and pdf free download. Relay energized on current flowing through the control circuit coil pins 1 and 3 creates a small magnetic field which causes the switch to close, pins 2 and 4. Aug 09, 2017 typical relay contains electromagnetic coil, no contact, nc contact and common contact, electromagnetic coil accepts low voltage dc bias and becomes electromagnet to attract the common terminal lever and interchanges the connection between nc, no contacts.
In this article, the basics of a relay like energized relay and deenergized relay are explained in detail. Definition of protective relay a relay is automatic device which senses an abnormal condition of electrical circuit and closes its contacts. Electrical and electronic switching as well as protection systems use different types of relays reed, thermal realay etc that employ both ac and dc supplies. Types of relays the relay may be defined as an electrical device interposed between the main circuit and the circuit breaker in such a manner that any abnormality in the circuit acts on the relay, which in turn if the fault is dangerous then it causes the circuit breaker to isolate and so to remove the faulty element. The pole represents the number of individual power circuits that can be switched. Oct 11, 2017 a relay is classified into many types, a standard and generally used relay is made up of electromagnets which in general used as a switch. In addition to the onoff switch, many circuits contain switches that control how the circuit works or activate different features of the circuit. In addition to the onoff switch, many circuits contain switches that control how the. Types of electrical switches in the home the spruce. Your source for electrical relay switches, mechanical relays and more at low prices. We offer a wide array of products with applications across many industries. It is the combination of both electromechanical and solid state relays.
All the relays react to voltage or current with the end goal that they open or close the contacts or circuits. Electrical switches are binary devices, they can be either completely off or completely on. An electrical switch which uses an electromagnet to move a switch from off position to on position instead of using a person to move switch is called as a relay. What is relay and different types of relays pdf elprocus. Different types of relays, their construction, operation. Different types of relays, their construction, operation electrical. Based on operation mechanism protection relay can be. Types and revolution of electrical relays introduction. 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. Types of electrical protection relays or protective relays. But when fault or undesirable condition arrives relay must be operated and function correctly. Also, the design, construction, working, applications, and also relay selection is explained in detail.
Semiconductor elements transmit and cut the signal or power and contacts are used to supply the power for the relay. Sep 26, 2015 based on the number of poles and throws, switches are classified into following types. Two types of relay technology are available, mechanical and solid state. Switch operators can be found in various shapes and sizes, such as toggles or buttons, and can be furnished in a variety of colors. Relay classification, principle of different types of electromagnetic relay. This p roduces a retarding effect on motion of the rotor in either di rection. Philosophy of protection, nature, causes and consequences of faults, zone of protection, requirements of a protective scheme, basic terminology components of protection scheme. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. A relay is classified into many types, a standard and generally used relay is made up of electromagnets which in general used as a switch. The solid static relays was first introduced in 1960s.
721 884 223 1060 713 1158 1424 512 1419 985 296 1234 785 700 572 1199 1206 1046 221 290 1078 554 1089 314 186 1114 380 1090 160 54 862 1373 653 991