Safety Circuit - EDM?

Well-designed and thought-out #machinesafety is paramount per OSHA 1910 requirements. This means that the user of the machine will be responsible for a worker's safety around the machine, with all resources available (hard guarding, engineering controls, procedure, PPE, etc).

#externaldevicemonitoring (EDM) and a #monitoredreset are necessary to ensure when the #safetyfunction is reset, the machine doesn't just take off, resulting in an injury. The concept is simple: have contacts from the hazardous motion/energy linked into the #safetycircuit (typically a safety relay or safety controller) in such a way that the motion or energy must transition from off to on as the safety function is reset.

You may see this below in the drawing from ANSI B11.26 for the #EDM circuit. We have 2 normally closed, series-connected contacts, (which could be parallel as well depending on the design requirement) through a reset pushbutton to the EDM circuit on the #safetyinterface. This circuit will ensure that the safety interface is not allowed to reset the safety function until; 1. the hazard is without motion/energy, and 2. the manual reset is pushed. The 3rd component is that the EDM circuit expects to see a transition from closed to open as the NC contacts for the MCPE1 and 2 are energized (changes state from off to on). If it does not see this transition, the safety interface will drop out, removing power to the actuator.

Why do I bring this up? Many safety circuits in NA are not designed to meet these requirements. This means that there will be many accidents this year, and in the years to come, due to inadequate design.

Are you sure your design is safe? Will OSHA agree with you when investigating an incident? If you are not sure, please call us, our team of #safetyexperts can help.

See Leuze safety products, services, and solutions here: https://www.leuze.com/en-us/focus-topics/safety-at-leuze