You can use a safety relay of that type in category B, 1 and 2 circuits too. 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. The contactors is primarily used for switching larger power circuits (such as motors, for example), since the control logic components cannot meet the current & voltage duty of the power circuit. Contactors and relays perform the same task and operate under very similar principles. Top 7 Difference Between Contactor And Relay: 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 0.1 A to 20 A. By common usage, the term, “contactor” is applied to a special type of device that is functionally similar to the relay. The system controls the contactor on/off with temperature controller (PID regulator with relay control output) and intermediate relay and then controls the electric heater. A contactor is a special type of relay used for switching an electrical circuit on or off. The Basics. It includes a contactor as an essential component, while also providing power-cutoff, under-voltage, and overload protection. For example, a safety relay rated to category 3 means that you can use it in your safety-related parts of your control system up to category 3. A PLC may be used to control the operation of a medium-voltage motor, perhaps 2,300V or 4,160V. NO contact is for trip signaling and NC contact is for disconnecting the contactor. It is but one component of a starter and is rated by voltage. In a relay-based control system, relays are used to interface the input devices with the output devices. Yet, a contactor is not normally called a “relay.” Rather, the term, “contactor” is used to describe a type of device that is used very much in the same manner as a relay. Protective relays and circuit breakers must work together to isolate a fault. Any one of the the three areas can cause a contactor or relay to malfunction. A control relay is, in essence, a switch that is controlled by electrical current.A control relay is an electrical component that opens or closes a switch in order to allow current to flow through a conducting coil, with the coil not coming into direct contact with the switch. Examples of Motor Control Summary. Comparing PLC vs Relay tablewise! Control relay switch chattering noises or chattering at contactor switches in air conditioners, heat pumps, water pumps. A relay is an electrical switch that has a set of control terminal & contact terminals. NC contacts should be capable of direct switching of contactor coil. In low-voltage (below 1,000 volts) industrial electricity, there is some overlap in these categories. They are used in large quantities for the indirect control of motors, valves, clutches and heating equipment. Test button. In addition to the simplicity which they offer in project engineering, panel building, commissioning and maintenance, the high A contactor has three components. They are used for switching relatively high power circuits using low power signals. Chattering Relay Switch Noise Causes & repairs for clicking chattering relay switches in HVAC, Pump, & other controls. Here are a few of the basic differences that distinguish different types of relay and contactor switches. A relay is used to energize the starter, which, in turn, switches the motor voltage while the PLC controls the relay. This page compares Relay vs Contactor and mentions difference between Relay and Contactor.. What is Relay? The contactor is mostly used in applications where higher current carrying capacity is involved, while the relays are used for lower current applications. This includes power contacts, auxiliary contacts, and contact springs. January 24, 2019. Control relays are an extremely important electrical part, and they play a vital role in today's electronic devices. Contact of a relay can be used to connect or disconnect the coils of a contactor. Easy to install and mounted in multiple orientations. In general, an electro-mechanical contactor is rated for a specific It is used for switching an electrical circuit on and off. Contactor relays Contactor relays Contactor relays are often used in control and regulating functions. 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. 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