The Safety Relay – Keeping Your Parts and People Safe

When it comes to safety, there are no shortcuts.

The old adage, “safety first,” should be priority number one in every case. Around machinery? “Safety first” is no lighthearted idiom. It’s life-saving advice.

But we are often faced with situations we can’t always control, especially around complex hardware and machines. Moving parts, complicated circuits, high temperatures, huge amounts of power, even savvy operators trying to boost productivity, these are all factors that contribute to hazardous environments that are begging for trouble.

So what can we do to stay safe? This is a question we should ask ourselves when working with hardware and machinery.

Most of the time, safety is a straightforward task. Use common sense. Impose and enforce safety regulations. Make sure personnel adhere to safety policies. And integrate measures into equipment to prevent accidents.

Be redundant. Be proactive. Take that extra step.

Just of one of the many steps, protocols and components that reduce risk is the safety relay, a staple in manufacturing industries and highly regarded for its simplicity, efficiency and reliability.


pilz pnozx

Pilz PNOZ X Series Contact Expansion Safety Relay, available at


What is a safety relay? It’s simple. Safety relays function like any other relay, receiving one signal and sending out another. Their primary concern, of course, is safety. Is it safe to turn this machine back on? Is someone accessing the guts of the machine to troubleshoot or load new parts? Is a part of the circuit at fault? Is someone frantically smashing the emergency stop button?

Safety relays can be configured to respond to any of these scenarios, shutting machines down and keeping the shut down, making sure hazardous situations don’t get out of control.

Now that we know what they do, let’s take a look at how they work. Remember, safety relays receive signals and send them back out. What happens between those signals is what’s important. Functionally, a safety relay is switch between in and out. If all is well going in, the relay simply sends the signal along, like a casual bystander.

But the relay is anything but a bystander. It’s on high alert. If something happens to the signal along the way to the relay, and the signal is wrong, the relay will switch. The relay can be configured to respond to all kinds of different inputs, so the switch could occur when a guard door opens, or if too much power is surging to the machine, or if there is short or weld somewhere along the line that damages the circuit. Whatever the case, the relay switches and that signal relayed to the rest of the machine telling to shut down.

Safety relays are available in different forms, using different mechanisms to accomplish their tasks. Common relays are electromechanical in function, relying on current to generate a magnetic field. The magnetic field activates moving parts, engaging or disengaging a switch. Solid-state relays have no moving parts. Force-guided relays add another line of defense, by making sure that no two contacts can be in the same position at once. The protects against welds or other mechanical malfunctions. New relays are digital, analyzing current digitally and using simple processors to decide whether to switch or not.


electromechanical relay

Typical electromechanical relay, which uses an electromagnetic field to move an armature into open or close position.


Now matter which type of relay you choose, you can be sure that the safety relay’s simple design is efficient and reliable. They provide predictable results and can switch thousands of times before failure.

Don’t take shortcuts with your safety. Be redundant. Be proactive. Take that extra step.


Share This:

Posted in:

Leave a Reply

Your email address will not be published. Required fields are marked *