Relays are designed to control an electrical circuit’s contacts in the event of parameter or condition change. A type of electromagnetic switch, they spring into action when overloads are detected, often switching many times during an operating cycle.
Contactors, on the other hand, have a physical electrical connection, based on the voltage being applied to the system. Both have different load capacities, with relays used for low-voltage electrical loads of about 10 amperes or less and contactors handling high-voltage demands greater than 10 amperes.
Contactors can be used for a variety of industrial applications, including lights, motors, pumps, and commercial HVAC systems. They can also be used for controlling electrical power to a variety of equipment, including automated assembly lines and conveyors.
There are three main types of contactors: auxiliary, power, and contact spring. The three differ from one another in configuration and the type of electrical load they control. Spring-loaded contacts are specifically designed to open or close a circuit when triggered by an electrical impulse. Auxiliary contactors provide additional control functions, such as remote control, and provide protection against overcurrent. Power contactors are designed to handle the high-voltage loads demanded by larger motors and other machinery.
Industrial contactors make it safer to indirectly control high-voltage and very high-power electrical devices such as motors and lighting. They are very valuable in potential cases of overload and where failure to de-energize a system would result in damage to internal parts or put people at risk.