Programmable Logic Controllers (PLCs) have revolutionized the way industries manage their automated processes. One essential component of these systems is the PLC control relay, a device that plays a crucial role in controlling heavy electrical loads such as motors, lights, and other machinery. This article explores the functions, principles, and applications of PLC control relays, shedding light on their importance in modern industrial automation.

What is a PLC Control Relay? A PLC control relay is an electrical device that acts as an intermediary between the PLC and high-voltage equipment. It uses an electrical signal sent from the PLC to control the switching of electrical circuits, allowing PLCs to manage large machines and devices without directly handling high current. Essentially, relays amplify the small control signals generated by a PLC to operate larger, more powerful systems. The Working Principle of PLC Control Relays The basic function of a PLC control relay is simple： it receives a low voltage signal from the PLC and uses this signal to activate or deactivate a set of contacts that control the connected load. This operation is typically accomplished through an electromagnet inside the relay. Here’s a closer look at the process：