Manufacturing AUTOMATION

When to use multi-function safety relays: white paper

August 1, 2014
By Manufacturing AUTOMATION

Aug. 1, 2014 – AutomationDirect’s new white paper, “When to Use Multi-Function Safety Relays,” explains how to determine when applications will benefit from multi-function safety relays over other options.

Many machines and robots require safety circuits to stop all or part of an operation in the event of an emergency. Safety circuits are also used to keep all or part of a machine or robot from running while there is human activity in close proximity, either for normal operations or maintenance.

The white paper describes how one or more multi-function safety relays can often be used to replace many basic single-function safety relays, simplifying installations and saving money. In many cases, multi-function safety relays can be used instead of a safety-rated PLC, resulting in substantial savings while streamlining implementation and maintenance, the company says.

The white paper also explains that machines and robots with just a couple of basic safety inputs, such as an e-stop and one or two door switches or other safety-related inputs, are typically best served by a safety system with one or two single-function safety relays. When a machine has many I/O points, with a high proportion safety-related, a safety-rated PLC is often the best fit. But for a machine or robot in between these two extremes, an easy to configure and inexpensive safety system using multi-function relays may be the preferred choice.


The paper provides an example of a limit switch manufacturer that upgraded to a multi-function safety relay system for its production cell to accommodate increased automation of the processes used in the construction of its products. By switching to a multi-function safety relay instead of adding more single-function safety relays, the company saved 30 per cent of the initial cost, and gained a much more flexible safety system.

Click here to view the white paper.

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