Motor starters, contactors, and relays all operate on the same basic principle. A coil is energized and the normally open contacts from the contactor close normally 3. Relay vs contactordifference between relay and contactor. Contact of a relay can be used to connect or disconnect the coils of a contactor. Contactors are used for loads that have high voltages, high currents, or both. Contactors and relays are used to turn on or off different parts of circuits. A contactor is used for switching of motors, capacitors, lights etc, that drains very high current. Difference between electromechanical relays and solidstate relays relays are electrically operated switching devices, used to gain control over processes and circuits. O contator e o rele sao dois termos frequentemente encontrados ao lidar com circuitos eletricos. Ive expanded the original question from what are the differences between relays, contactors and motor starters. Fundamental difference is that relay is a sensing device where as circuit breaker is a fault interrupting equipment.
Because contactors and relays are often rated similarly and intended to do the same type of job in an application, its common for people to be confused over the difference between a contactor and a relay the main difference between them are the loads that they can handle. This page compares relay vs contactor and mentions difference between relay and contactor what is relay. Explained main differences between relay and contactor. The electronic circuit provides the power to turn the relay on, which in turn switches a larger voltage source needed to turn on a contactor. Although they have been explained in earlier posts, their wide use and significance needs to be explained in detail. Difference between contactor and relay difference between. What is the difference between contactor and relay. Designed for continuous duty cycle, the c100 series offers heavy duty contacts to ensure long electrical life. Iron core of the ac contactor is usually laminated by silicon steel sheet, so as to reduce the eddy current and hysteresis loss generated by alternating magnetic field in iron core, avoid the iron core overheating. What is the difference between solidstate relays ssrs and contact relays.
When the electricity of one store,ie, is turned off we apply a small signal to activate the contactor,a large box. If you look at the specs for your 5a relay, it will likely tell you that the inductive load rating is only 1a, and if you look at the 5a contactor, it may tell you that the resistive rating is 9a. The robust c100 series contactor relay is available as a 2 or 3 pole relay. In essence, to turn things on and off, we need devices that are switchable by application of a current or voltage. Choosing between a relay and a contactor isnt really difficult. Relays and contactors both perform the switching operation. Reliable performance is attained by rectifying the 400hz ac to dc and using a dc relay motor. The main difference between relay and switch is that the relay is a electrically operated switch and switch is a electrical component that can break an electrical circuit.
What is the difference between a relay and a contactor. The main difference between relay and contactor is, relay is a low power device whereas contactor is high power device. All moeller contactor relays have doublebreak contacts. Due to the acs shading coils, the device can be placed in any location, as long as it has room to operate.
So, if a relay has a same switching current with a contactor, which one to choose. They transfer current from a source line to a work load. Numerical relays are based on the use of microprocessors. The main difference between contactors and relays is the loads that they are meant to handle. It consists of a set of input terminals for a single or. Based on their principle of operation they are classified into two types. Difference between a battery and a capacitor a motor starter is a combined device of contactor and over load relay. Whenever the electromagnetic coil is excited, it attracts the armature and closes the contacts. Contactor s typically have an inductive rating, relay contact ratings are typically resistive. A contactor, as far as being used to start a motor or the like, is in essence, a relay.
Both these devices are used for similar purposes and hence people are often confused about the difference between a contactor and a relay. Manual guidelines for contactor inspection and maintenance. The difference between electrical relays electromechanical relays vs solidstate relays by. The easiest latching relay circuit to understand ever. Based on the application contactor power ratings are chosen.
Megan tung a relay is a power switching solution used to allocate power without manually opening and closing a switch. A contactor only has one in and one out so in a no. In fact, the most important difference between contactors and relays is that the contactors have arc extinguishing devices, while the relays. The difference comes if we see from the application perspective. Omron sysdrive 3g3rv series user manual pdf download. Difference between contactor and relay since a contactor is required for a higher load, a relay is always cheaper than a contactor. What is the difference between relay and circuit breaker. Difference between contactor and relay compare the. The contactor is the relay to use when a circuit must support a heavy current load. Selecting a solid state relay or a solid state contactor for.
The contactor is mostly used in applications where higher current carrying capacity is involved, while the relays are used for lower current applications. Ssrs are not very different in operation from contact relays electromagnetic relays. A mercury relay, sometimes called a mercury displacement relay, or, mercury contactor, is a relay that uses the liquid metal mercury in an insulated sealed container as the switching element. The user should establish compatibility between his cleaning fluid and the relay plastics. Safety compendium, chapter 4 safe control technology pdf. A relay is normally used in appliances below 5kw, while a contactor is preferred when the appliance is heavier. What is the difference between relay and contactor answer pankaj relay. Therefore, this document is intended to describe about a few basic types of relays that are popularly used in typical loadcontrol. Current splits inside the relay, supplying power to both the control and load circuits. Contactors are compact and can be field mounted easily. The difference between the relay and circuit breaker is explained on the various factors like the their principle, working, type of device, usability etc. Contactor relays 2 and 3 pole relay cit relay and switch. Difference between contactors and relays electrical classroom. For 6 and 8 pole contactor relays, the e version means that.
Contactors electromechanical relays electronics textbook. Difference between ssr and contact relay faq india. Relay is a protective device which senses the faulty conditions in a power system line and initiates the operation of circuit brea. Numerical relays protection and control products for. Solid state relays ssrs and solid state contactors sscs are essentially if not exactly, the same functionally. Identify maximum amperage and maximum voltage going through contacts. The relay is an automatic protective and switching device which is capable of sensing abnormal conditions in electrical circuits. It is totally normal for a contactor or relay to wear out and need replacing periodically. Contactors are used for devices that pass more than 15 amps or loads of more than 3kw.
Click to share on twitter opens in new window click to share on facebook opens in new window like this. Difference between relay and circuit breaker the difference between the relay and circuit breaker is explained on the various factors like the principle of their operation, working of relay and circuit breaker, type of device they are, voltage, their usability and whether it works as an amplifier or not. A relay is utilized when it is necessary to switch a small amount of power to a larger amount of power. Both of them can be differentiated on the following bases. The differentiation between them is that by definition a contactor must carry a motor control rating in hp or kw, whereas a similar solid state relay. Main difference between contactor and starter electrical. The coil of a relay or contactor is used to close the contacts by creating a magnetic field that will pull the plunger into the magnetic field. Some contactors come with additional auxiliary contacts that may be either no or nc. Relays can be used for many different control applications including controlling fans, blowers, other relays or contactors, valves, dampers, pumps and much more. What is the difference between the relay and the contactor. Other relay variations include three and five pin relays.
If you see from the application point of view, you would have seen contactors placed in control panels of industrial motors or other heavy loads. Generally, a relay has several opening and closing contacts. One of the major differences between relays and contactors is that both are not used to handle the same kind of load. Explain the difference between a manual contactor and a magnetic contactor. Coil of the dc relay has a large reactance, but small current. By design and construction they ensure potential isolation between the actuating circuit and the operating circuit, in the deenergized state, between the contact input and output. Common applications include industrial electric motors used in heavy trucks and equipment, buses, emergency vehicles, electrichybrid vehicles, boats, light rail, mining, and other systems that simply require too much power for a standard relay. If the coil of a relay or contactor is faulty, the device will not close the contacts.
Because of this, relays are often used as a middleman between the electronic circuit and the contactor. A contactor joins 2 poles together, without a common circuit between them, while a relay has a common contact that connects to a neutral position. Difference between solidstate and electromechanical relays. Both are electromagnetic switches and operate under similar principles. Solenoids, relays, and contactors may seem similar but there are some crucial differences to know. It has at least a single pair of three phase input and output contacts. Contactor relays are often used in control and regulating functions. Relays are classified into several types based on their functionality and application they are implemented for. As the contactor need to pull the metal core it need more magnetic power than relay so switching noise will generate in contactors.
Contactor and relay are two terms often encountered when dealing with electric circuits. Moreover, contactors are normally appraised for up to v, while relays are generally evaluated to just 250v. However, on the one hand, a contactor is used for switching of motors, capacitors, lights and other devices that drain very high current. Diferenca entre contactor e relay 2020 es different.
Electrical controls for heating and air conditioning, contactors, relays, transformers, sequencers, time delays. What is the difference between a contactor and a relay. This section explains the differences between a circuit breaker and a contactor, which both make and break a circuit. It is a special type of relay, but there is a basic difference between the contactor and a relay. Therefore, ssrs have a variety of features that contact relays. Safety relays can be thought of as a cross between a relay. Also find hard to find transformers, contactors, and relay replacement parts. Much like a relay, a contactor is an electrically controlled switch. There is a lot of confusion around the industry about the difference between contactors and relays and many times the terms are used nearly interchangeably.
Ssrs, however, consist of electronic parts with no mechanical contacts. Both, contactor and control relay, have a top housing which have set of normally open or normally closed contacts. Continuous current ratings for common contactors range from 10 amps to several hundred amps. With a convenient mounting plate, the c100 offers ul class b insulation resistance.
Rather, the term, contactor is used to describe a type of device that is used very much in the same manner as a relay. By design and construction they ensure electrical isolation between the actuating circuit and the operating circuit, in the deenergized state, between the contact input and output. They are used in large quantities for the indirect control of motors, valves, clutches and heating equipment. An electromagnetic coil is provided for opening and closing of contacts. The arcs produce additional heat, which, if continued, can damage the contact surfaces. Page 58 installing a magnetic contactor if the power supply for the main circuit is to be shut off during a sequence, a magnetic contactor can be used. Contactors and relays perform the same task and operate under very similar principles. Contactor vs relay difference between relay and contactor to turn things on and off, we need devices that are switchable by the application of a. A big difference between conventional electromechanical and static relays is how the relays are wired. Relays are components in electric circuits which are used as a switch.
A device by which contacts in one circuit are operated by a change in conditions in the same circuit or in one or more associated circuits. Contactors and relays are two closely related terms leading to confusions and misinterpretations most of the times. The relay is usually used in the electrical control circuit, its used to extend the contact capacity of a micro or small relay, so as to drive larger load. Contactor vs relay electrical engineering stack exchange. Power level in relay circuit can be as low as 12 24 v dc or ac for coil, while main power circuit could as well be 230 v single phase, or 440 v three phase power. Of course, the relay can also perform certain special functions, such as logic operations, through proper connection. Top 7 difference between contactor and relay electrical4u. Electrically, we have transistors and integrated circuits. Dec 04, 2018 a contactor contains an electromagnetic coil, an armature, and contacts enclosed in an air tight container. June 29, 2019 leave a comment on difference between contactor and relay. Contactors and relays perform the same task of switching a circuit.
Additionally, contactors are commonly rated for up to v, while relays are usually rated to only 250v. These classifications include electromagnetic, solid state, high voltage, thermal relays, and so on. Whats the difference between a contactor and a control relay. Mar 25, 2015 difference between relays and contactor vaisakh tt.
Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also. Contactors have more rugged construction than relays. Contactors and relays cuber filter driers flaker nugget oil treatments poe oil. All dil contactor relays have doublebreak contacts. The main difference between a circuit breaker and a contactor is that a circuit breaker is designed to detect and switch a shortcircuit current and overload current when applicable,whereas. Mar 12, 2017 contactor vs relay difference between relay and contactor to turn things on and off, we need devices that are switchable by the application of a current or voltage. The relay is controlled device which opens and closes contacts in order to effect operation of other devices in the same or another electric circuit. The main difference between contactors and relays are the loads that they are intended to handle. A reader submitted a question through the ask chris form. As known, contactor is used to switch higher capacity than relay. The first three steps for selection will be the same. Its coil is wired in parallel with the safety circuits, and in series with the contactor coil. The dc contactor needs air when operating, so the device must have plenty of gaps around it to perform properly. Contactor vs relay difference between relay and contactor.
Both have an external envelope to protect all the internal parts from the external environment. A 90340 is a very common, versatile relay that many techs have on their truck so we will use it as the example. Feb 07, 2010 major difference between relay and contactors are. The defining differences are not always clear, so we thought wed try and help sort out the answer.
Difference between contactor and relay engineering and. A contactor combines 2 posts, without a typical circuit between them, while a relay has a typical contact that associates with an unbiased position. Contactors typically have multiple contacts, and those contacts are usually but not always normallyopen, so that power to the load is shut off when the coil is deenergized. A contactor is a relay that is used for switching power. Relays are basically switches which are primarily used for the protection of equipment. The main difference between contactors and relays is that relays are used with small currents whereas contactors are used when the currents are large what are relays.
Its points are a part of the safety circuit so that when the impedance relay is energized by the opening of a safety control it locks out the contactor. Lastly, the mammoth relay on the far right is an automotive power relay, which is rated at 60 amps. They usually handle very heavy loads like an electric motor, lighting and heating equipments and so on. However, the basic difference between the relay and contactor is that the contactor is used in applications with higher current carrying capacity, whereas the relay is used for lower current applications. Difference between ssr and contact relay faq india omron ia. The contactor relay contacts themselves constitute a considerable safety feature. In motor starter, contactor controls the flow of electric current to the connected motor and repeatedly make and break. But there some relays can switch high current too, such as, some power relays can switch current beyond 100a, and there are contactors to switch only 160a. Shop our parts hvac online store for transformers, contactors, and relays hvac supplies and accessories. Difference between relay and circuit breaker circuit globe. By common usage, the term, contactor is applied to a special type of device that is functionally similar to the relay.
Contactor relay coil voltage ranges from 24vac up to 240vac. Another important difference between the contactor and relay is, as the switching speed of the relays are very much faster than contactors. Different types of relays and conactors contactor vs relay. The main difference between the contactor and relay is that, contactor is a high power device while relay is a low power device. Relays are used in a wide variety of applications like electric power systems, home. Contactors, and relays for hvac are available at wholesale and quantity pricing. Hvacr electricalcms, 10 of 14, relays, contactor, and starters. To turn things on and off, we need devices that are switchable by the application of a current or voltage. What is the difference between relay and contactor answer wleob. A contactor is an electrical device which is used for switching an electrical circuit on or off. A mercurywetted relay is a form of relay, usually a reed relay, in which the contacts are wetted with mercury.
Load capacity contactors are used in control circuits with both low and high ampere capacity that is between 15a to 12500a. When a magnetic contactor is installed on the primary side of the main circuit to forcibly stop the inverter, however, the regenerative braking does not work and the inverter will coast to a stop. Electrical contactors and relays hvac parts online. Contactor is a type of relay where a small current in one circuit controls a much larger current in power circuit. Also, other disturbances in the control voltage such as poor relay contacts or too small control transformerpower supply could be. Difference between relay and contactor cr4 discussion thread. The bottom housing in both cases, have a set of magnet and coil with external cover to protect all the internal parts. When a relay is used to switch a large amount of electrical power through its contacts, it is designated by a special name. These are operated to open or close the load contacts in response to one or more electrical quantities like voltage and current. This p roduces a retarding effect on motion of the rotor in either di rection. The contacts are opened and closed by exciting this electromagnetic coil. Difference between a switch, relay, circuit breaker and contactor. Relay and contactor are functionally doing same duty, but the major difference between relay and contactor is that, contactor can carry huge amount of current but relay can carry only less amount of current from 0.
In electricity the use of a relay is the same, you use a relay to switch between loads or between sources, you have one terminal with two possibilities, in a nc relay if not powered youre using one contact and when the relay is powered you use the other, or backwards if the relay is a no. Relays and contactors use a variety of technologies to switch signals and power. Ssrs solid state relays use semiconductors for nocontact operation. The key difference between control relays and contactors is the rating of current that they are designed to handle.
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