Contactors

A contactor is an electrical component that is similar to a relay in many way but it typically used in larger scale applications.

Contactors are essentially switches that can be controlled remotely. They can be designed to operate at voltages similar to the control devices that control their state or they can be designed to operate at voltages similar to the loads that they control.

Contactors have features that distinguish it from a standard relay. In most cases, a contactor is designed specifically with high current usage in mind. Other differentiators to relays are as follows:

  • Most contactors are designed to be used in the normally open position. Relays can typically be used in two configurations; normally open or normally closed. There are variations to this but this is typically the norm.
  • Contactors are typically larger than a relay in physical size. Small contactors are typically around the size of a person's hand. Contactors can get much larger than that and are sometimes large enough to require heavy equipment to move from place to place and install.
  • Due to the operating conditions in which contactors are used, there are vastly different considerations that go into their manufacture than go into the manufacture of their smaller cousins, relays. Most contactors have some sort of an arc suppression system included in their design that greatly increases their lifespan.

What is meant by ’normal state’ configuration of a contactor?

The normal configuration of a contactor describes the disposition of the contacts when current is not applied to them. Most contactors are normally open, meaning that they close in the presence of current. There are variations, but this configuration is one of the defining characteristics of contactors and one of the things that separates them from standard relays.

Contactor uses

Contactors are typically used for very heavy duty industrial scale applications and their ratings systems is designed to reflect this. They come in different classifications under IEC 60947-4-1. These classifications are expressed as AC numbers, from AC-1 to AC-4. Other classification systems are also used.

The applications of contactors include starting motors, providing control over furnaces, controlling the speed of very large motors and other large-scale applications.

Guides & Articles

article1_image

In our definitive guide, we look at what flow switches are, how they work and what they’re used for, as well as the different types that are available.

article1_image

In our comprehensive guide we look at what thermocouples are, what they’re used for, as well as the different types that are available.

Related Products
Residual Current operated circuit breaker for Personnel and ...
Description:
Residual Current operated circuit breaker for Personnel and fire protectionFree from FCKW and silicone2 or 4 poleInstant tripping, surge current withstand capability >1kAMains connection alternatively from above or underneathReciprocally sleeve terminals with wire protection Lower combination clamp for the ...
acoustic signal device, compact, 22 mm, round, plastic, ...
Description:
acoustic signal device, compact, 22 mm, round, plastic, black, Continuous tone 2.4 kHz, IP40, Sound pressure min. 95 dB/10 cm, with holder, Operating voltage 24 V AC/DC, screw terminal.
The RS PRO 12mm diameter, black through-hole buzzer ...
Description:
The RS PRO 12mm diameter, black through-hole buzzer is an electromechanical transducer with PCB pins. It is continuous tone buzzer with a minimum sound output of 85dB at 1m for its size. It has an electrical rating of 12Vpp and ...
Acoustic signal device, compact 22 mm, round, metal, ...
Description:
Acoustic signal device, compact 22 mm, round, metal, black, Continuous tone 2.4 kHz, IP40, sound pressure min. 90 dB/10 cm, with holder, operating voltage 24 V AC/DC, screw terminal.