An attached spring returns the armature to its original position. Different types of relays and conactors contactor vs relay. How relays work relay diagrams, relay definitions and relay types. In this post will see a brief understanding of various types of electrical relays. It detects the intolerable or undesirable condition with an assigned area and gives the commands to the circuit breaker to disconnect the affected area. The induction type relays are also called magnitude relays. Mechanical life is the number of operations openings and closings a contact can perform without electrical current. A relay is automatic device which senses an abnormal condition of electrical circuit and closes its contacts. What is relay and different types of relays pdf elprocus. The term instantaneous means having no intentional time delay and is applied to relays that operate in a minimum time of approximately 0. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof relays are used where it is necessary to control a circuit by an. 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. Concept and working of different types of fuses protection. Types of electrical protection relays or protective relays.
Types of relaysoverload protection relay,solid state. The first static relays developed were the high speed differential relays and the distance relays. These relays plug into multipin base sockets for easy removal and replacement in case of failure. The working principle of the solid static relays is similar to that of the electromechanical relay which means the solid static relays can perform tasks that the electromechanical relay can perform.
Also, the design, construction, working, applications, and also relay selection is explained in detail. Electromagnetic relay working types of electromagnetic relays. Most relays are encased in a plastic or metal housing to keep the moving parts free from outside interference and dust see figure 21. Before extending to the various types of relays, i will. Mar 25, 2017 different types of solid state relays ssr and their working classification of solid state relays ssr ssr definition. This is known as relays datasheet to rate its coil voltage. The switch may have any number of contacts in multiple contact forms, such. Different types of relays used in protection system and their.
Some relays have plastic covers to help keep dust and moisture away from the electrical contacts. Both accomplish the same result but the physical structure and functionality makes them different. One of the more important parts of any electrical relay is its coil. It takes a relatively small amount of power to turn on a relay but the relay can control something that draws much more power. In electromechanical relays contacts are open or closed by a magnetic force. A relay is an electrical switch that uses an electromagnet to move the switch from the off to on position instead of a person moving the switch. Generally, control relays are intended for controlling relatively low current applications, more or less in the range of 300 va to 2000. Protective relaying senses the abnormal condition in a part of power system and gives an alarm or isolates that part from healthy system. Types of relays and relay driver circuit buchholz relay. The most common types of actuators or output devices are electrical relays, lights, motors. Terminal 86 supplies power to the relays internal electromagnet.
Once contacts burn out, the relays contacts or the entire relay has to be replaced. The working principle of electromagnetic relays is the electromagnetic action. A relays mechanical life is relatively long, offering up to 1,000,000 operations. Electromagnetic attraction relays working,construction. A relay is a device that detects the fault and initiates the operation of the circuit breaker to isolate the defective element from the rest of the system. In electromagnetic attraction relays, there is a coil which energises an electromagnet. How does a relay work and types of relays 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 must. Under normal power system operation, a protective relay remains idle and serves no active function. The coils of the electromagnets are energised with the help of alternating currents.
Iso micro relay types below are two popular micro iso relay configurations. It is the movement of this part that opens or closes the mechanical. A common package for industrial relays is the socalled ice cube relay, named for its clear plastic case allowing inspection of the working elements. Other types of commonly used relays include the time delay relays, protection relays, solid state relays and reed relays. Relay driver circuit using ic uln2003 and its working. Types and revolution of electrical relays introduction. In this article, the basics of a relay like energized relay and deenergized relay are explained in detail. Both ac and dc relays work on the same principle as electromagnetic. These relays work on the principle of the induction motor or an energy meter.
The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof. All the relays respond to one or more electrical quantities like voltage or current such that they open or close the contacts or circuits. The first static relays developed were the high speed differential relays. 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. Therefore, this document is intended to describe about a few basic types of relays that are popularly used in typical loadcontrol applications. Types of electrical relays electrical basics tutorial.
Most of the devices have the application of relays. Solid state relay has a capability to control a larger load current or voltage. Electrical relay and solid state relays for switching. Here you can see a variety of relays in small to large sizes. The working principle is that if the current is in excess then the strip would melt and break the circuit. In order to eliminate voltage spikes from a relay circuit, a diode is required for its proper functioning. Types of protection relays are mainly based on their. Relays are essential for automation systems and for controlling loads.
In this article, we will see types of solid state relays and their working. Latching relays latching relays are electromechanical switches that are used when the switch needs to remain in its last position after the electrical current is turned off. Latching relay is really a generic term that is used to describe the type of relay that maintains its position after the power is removed. Fundamental relayoperating principles and characteristics 17 time delay and its definitions some relays have adjustable time delay, and others are instantaneous or high speed. For the function of relay, it must receive this voltage at its coil terminals. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. You can choose from a wide range of relays but do you know what type to. You can check the live working of the relay in below given animation. There are also other operating principles for its working. Also, relays are the best way for galvanic insulation between high and low voltage portions of a circuit.
Protective relaying is a team work of ct, pt, protective relays, time delay relays, trip circuits, circuit breakers etc. Oct 11, 2017 you can check the live working of the relay in below given animation. Different types of relays and their working principles relays are the primary protection as well as switching devices in most of the control processes or equipments. 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. Relays are used where it is necessary to control a circuit by an independent lowpower. The conducting part of the switch that makes closes or breaks opens a circuit. In these relays, a metallic disc is allowed to rotate between the two electromagnets. This is because the induction disc characteristics of the overcurrent relays inverse characteristics are not amenable to simple mathematical analysis. Show examples of relays garnered from the school auto shop, hvac shop and others. Attraction armature type relay is the most simple both in construction as well as in its working principle.
Solid state relay ssr types of ssr relays construction. Last week we talked about the standard din numbers used on relays and the incredible utility they represent. Latching relays are bistable, meaning they have two relaxed states. For instance, in the case of slow blow fuses, a small overload is carried for some period without the circuit been broken. Types of electromagnets relays are classified into the following types, depending on whether or not they have a permanent magnet. These relays are employed as auxiliary relay, control relay, over current, under current, over voltage, under voltage and impedance measuring. A dpdt ice cube relay is shown in the following photographs, ready to be plugged into its. How relays work relay diagrams, relay definitions and relay. Working of relayshow relay works,basics,design,construction. The protective relaying scheme includes protective current transformers, voltage transformers, protective relays, time delay relays, auxiliary relays, secondary circuits, trip circuits, etc. Aug 31, 2018 attraction armature type relay is the most simple both in construction as well as in its working principle.
There are mainly three types of solid state relays. In any circuit with a din relay, without looking at a wiring diagram, you know that. A solid state relay may be defined as an electrical switch that changes its state when an external voltage is applied to it. A relay is used to control the air conditioner in your home. Thus, if a relay has a rated voltage of 9vdc, it should get 9 volts of dc voltage for its working. It is used in application to turn on and off circuit by low power signal, or where several circuits must be controlled by one signal. When an electrical flow is turned off, the latching relay remains in the last state it was in. There are different variants of fuse boxes available with different types of circuit breaking. The three smaller relays on the bottom row are called signal relays, meaning their contacts are rated for less than 2 amps of. These types of electromagnetic relays can be utilized as either magnitude relay or ratio relay. Types of relays there are different ways to classify relays.
Only some of the relays are explained in this document for. It is used in application to turn on and off circuit by low power signal, or where several circuits must. The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. The size of a iso micro relay is a 1 x 1 x 12 square 12 as thick as a mini relay. Basically, relays are of two types either electromechanical or solid state relays. Different types of solid state relays ssr and their working. These contacts in turns close and complete the circuit breaker trip coil circuit hence make the circuit breaker tripped for disconnecting the faulty portion of the electrical circuit from rest of the healthy circuit. Different types of relays and their working principles elprocus. Relays consist of an electromagnet and also a set of contacts.
Different types of relays, their construction, operation. Learn what is a relay, how a relay works, how it is designed and constructed and what are. When power flows through the first circuit 1, it activates the electromagnet brown, generating a magnetic field blue that attracts a contact red and activates the second circuit 2. The relay is the device that open or closes the contacts to cause the operation of the other electric control. These type of relays are made of a coil that induces a magnetic field when it get energized and moves the armature, which closes of opens the contacts. When the voltage is shut off, the relay s switch opens, turning the device connected to it off. Types of relay based on the principle of operation. Related components from win source each component plays its own role, which is very important in the overall operation of the scheme. The following groupings will be used in this technical guide. The switching mechanism is carried out with the help of the electromagnet.