What are Control Relays?

Control relays are electromechanical devices used to control the operation of various electrical circuits and devices. They consist of a coil, which when energized, generates a magnetic field that pulls in an armature or contact assembly to make or break electrical connections within the relay.

Here’s how they typically work:

  1. Coil: The relay coil is usually made of copper wire wound around an iron core. When an electric current is passed through the coil, it creates a magnetic field around it.
  2. Contacts: Control relays have one or more sets of contacts that open or close when the coil is energized. These contacts can be normally open (NO), normally closed (NC), or changeover (CO) contacts. When the relay coil is energized, the contacts change their state accordingly.
  3. Activation: When the appropriate voltage is applied to the coil, it becomes magnetized, attracting the armature or contact assembly. This movement of the armature causes the contacts to change position, either closing or opening the circuit they control.

Control relays are used in a wide range of applications, including automation systems, motor controls, lighting controls, HVAC systems, and industrial machinery. They provide a way to remotely control electrical circuits without directly switching high-power loads using manual switches. Additionally, they can be interfaced with programmable logic controllers (PLCs) and other control systems for automated operation.