The Difference Between Relays and Contactors

The Difference Between Relays and Contactors

The relay works on the same principle as the contactor. The main difference is that the main contact of the contactor can bear large current, while the contact of the relay can only bear small current. Both relay and contactor are electromagnetic switching appliances, but the former belongs to the switching appliances working in the control circuit, while the latter belongs to the switching appliances working in the main circuit.The difference between relay and contactor as follows:

1. Different Function:

The primary role of the relay is signal detection, transmission, conversion or disposal used, its switch current always very low, generally used in the control circuit, control weak signals.

The primary role of contactor is to be used to switch on or off the main circuit. The main circuit refers to whether a circuit works or not is marked by whether the circuit is switched on. The concept of a main circuit corresponds to a control circuit. In general, a main circuit carries more current than a control circuit.

2. Different Way of Open and Close Contact

Large capacity contactors are generally equipped with arc extinguishers. The contact capacity of the relay generally does not exceed 5A. The contact capacity of the small-sized relay generally only needs 1A or 2A, while the contact capacity of the contacter is 9A at the minimum.Contactor contacts generally have three pairs of main contacts (the main contacts are always open contacts) and several pairs of auxiliary contacts. The contact of the relay is generally not divided into the primary and secondary;Relay contacts are sometimes set in pairs, that is, normally open contacts and normally closed contacts are combined together, while contactors are not set in pairs. Relays may be combined with other equipment to plan for specific needs into time relay counters, pressure relays, etc., which have additional functions that contactors generally do not have.

In addition, contactors are used to connect or disconnect loads of high power. In the main circuit, the main contact may have interlocking contacts to indicate the open and closed condition of the main contact. Relays are generally used in electrical control circuits to expand the contact capacity of miniature or miniature relays to drive larger loads. For example, relays can be used to connect or disconnect the coils of contactors. Generally, the relay has more open and closed contacts. Of course, the relay can finish some special functions, such as logical operation, by proper connection.

3. Arc-control Device:

In fact, one of the most important differences between contactors and relays is that contactors have arc-extinguishing devices, but the relay don’t have it.

All above is the difference between relays and contactors. For more details and free technical support, visit www.ivy-metering.com