Types of Contactors
A magnetic switch contactor operates entirely via electromagnetism and therefore does not need any direct intervention to perform its role consistently. This makes it one of the more efficient and reliable designs since electromagnetic switching only requires a small amount of power. It also enables the full remote operation of the contactor. Almost all electrical contactors work on this basis today.
Switch Ratings and Coil Ratings (Contact Voltage and Current)
Contactor switch ratings are usually given as two separate metrics - maximum switching voltage and maximum switching current. The upper limits of both voltage and current that a design, brand, or model of a switch can handle must always be directly assessed in terms of the requirements for the circuit or motor where it is being used.
While a product may be listed as a 230V contactor, 240V contactor, or 1000V DC contactor, more detailed manufacturer specifications will usually make direct reference to the maximum coil voltage, contact current rating, contact voltage rating, and overall power rating of a device. They will also list the number of auxiliary contacts, terminal type, normal state configuration, and minimum and maximum operating temperatures. Contactors generate more heat than relays, and this must be factored in when choosing a suitable unit for installation.
Various electrical ratings for contactors will often be given as either resistive or inductive, depending on the intended use of the module. Resistive ratings are more common for contactors being used with heating elements or lighting control installations, whereas inductive load ratings tend to be more common for motors, transformers, and solenoids.
It is also worth bearing in mind that the contactor coil voltage (control circuit voltage) does not necessarily have to be the same as the load voltage being switched on and off. For example, the coil voltage could be 24VDC, but the motor being switched on and off could be 400VAC. Typical coil voltages available include 12, 24, 48, 110, 230, and 400V.
Many leading brands are renowned for manufacturing high quality, reliable electrical contactor switches. Among the most sought-after suppliers we work with to supply our extensive range of switches and contactor accessories are ABB, Allen Bradley, Eaton, Lovato, Schneider Electric, Siemens, TE Connectivity and WEG.