Transcript:
[0m:06s] Hey, I’m Mitchell and welcome to another video in the RSP Education Series. Ever wonder how a tiny electrical signal can turn on a huge motor or machine? If you like this kind of content and want more educational videos, please like and subscribe. This video is for educational purposes only. Consult a professional for your application. RSP Supply is not liable for any misuse of this information. With that said, let’s dive in.
[0m:32s] So, what is a relay? A relay is an electrically operated switch that allows a low-power electrical signal to control a much higher-power circuit. Think of it like a gatekeeper, it listens for a signal and then opens or closes a gate, or in this case, a circuit. Relays have two main parts: the coil, which acts as an electromagnet that creates a magnetic field when energized, and the contacts, which open or close based on that magnetic field. When current flows through the coil, it pulls or pushes the contacts, changing the circuit’s state to turn something on or off. This means a small signal from a sensor or PLC can control large loads like motors, pumps, or lights.
[1m:28s] The history of relays goes back to the early 1800s, where they were first used in telegraph systems to reamplify weak signals over long distances. By the early 1900s, during the industrial revolution, relays became essential in controlling motors, heaters, and lights. They served as the brains behind control panels before programmable logic controllers (PLCs) were invented.
[2m:07s] In the modern era, we now have solid-state relays (SSRs) that perform the same job without moving parts. They’re faster, quieter, and more durable, though slightly more expensive and heat-sensitive. Still, traditional mechanical relays remain popular because they’re affordable, reliable, and easy to troubleshoot. Relays are vital in industrial control systems for several reasons. Isolation is key; they separate low-voltage control signals from high-power equipment, protecting sensitive electronics from dangerous voltage spikes. Remote control is another benefit, allowing operators to safely control heavy equipment from a distance using low-voltage signals.
[2m:58s] Before PLCs, relay logic—or ladder logic—was how automation worked. Relays were wired in sequences to perform logical operations such as start, stop, delay, timing, and interlocking. They’re also flexible and easy to rewire, making them ideal for smaller systems that don’t require full PLC control. Relays can also be configured in failsafe designs that default to an off state during power loss, improving safety.
[3m:37s] Bottom line: relays are the unsung heroes of industrial automation. Whether they’re starting motors, lighting warning lamps, or interlocking safety gates, relays remain everywhere in control and protection systems. Even with modern PLCs and smart systems, relays continue to play a crucial role in reliable, safe automation. That’s it for today’s introduction to relays. Thanks for watching, and visit rspsupply.com for relays and hundreds of thousands of other industrial automation products.