Transcript:
[0m:00s] Hey, I’m Mitchell and welcome to another video in the RSP education series. Ever feel like you’re drowning in relay details and forgetting the basics? Let’s take a quick step back because no matter how deep we go, the fundamentals always matter. Today we’re breaking down relays in the simplest way possible, how they work, when to use them over PLCs, and why old school relay logic still matters. Stick around because this one is packed with practical tips. 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. Let’s dive in.
[0m:54s] A relay is an electrically operated switch that uses a small control signal to switch much larger electrical loads. Think of it like a remote controlled switch where a small signal from a PLC or microcontroller safely controls a heavy motor. The basic components include the coil or electromagnet, which creates a magnetic field when energized, the armature that moves the contacts, and the contacts themselves, either normally open or normally closed. A spring returns the armature to its original position when power is removed.
[1m:54s] Relay operation follows a simple sequence. A small control voltage is applied to the coil, activating the electromagnet and pulling the armature. Normally open contacts close to allow current to flow to the load, while normally closed contacts open to break their circuit. When the control signal stops, the spring returns the contacts to their default state. This allows a small signal to safely control a high power device like a motor or light.
[2m:34s] Relay logic is the original automation control method using physical relays, switches, and timers wired together. It is hardwired, simple, robust, and easy to troubleshoot with no software required. Relay logic can handle high power loads directly. The downsides are that changes require rewiring, systems can become bulky, and flexibility is limited. PLC logic replaces physical relays with software based control. PLCs are compact, flexible, and offer advanced features like data logging, networking, and process control, but they require programming knowledge and have higher upfront cost.
[4m:10s] Relays are still the better choice in certain situations such as high power switching, extreme environments, simple fixed logic, and safety circuits that require fail safe operation. PLCs are the better option for complex logic, frequent changes, and networking needs like SCADA integration. To recap, relays use a small signal to control large loads, rely on coils, armatures, and contacts, and still dominate in rugged high power applications, while PLCs excel at flexible and complex control. For a full line of relays and hundreds of thousands of industrial automation products, visit rspsupply.com.