How do I calculate Safety Relay / Device Selection Helper?

To calculate Safety Relay / Device Selection Helper: Enter Safety function type, Required PLr, Sensor channels available and other values. Click Calculate. INDUGRID computes the result instantly using the formula: PL_sys = f(MTTFd, DCavg, CCF, Architecture category) — per ISO 13849-1 Annex K. No registration required.

Is the Safety Relay / Device Selection Helper calculator free?

Yes. The INDUGRID Safety Relay / Device Selection Helper calculator is completely free, requires no account or login, and works on desktop and mobile browsers.

Machine Safety

Safety Relay / Device Selection Helper

Guided selection of the appropriate safety relay type based on application, PLr and required safety functions.

Units:

in LinkedIn

💡Safety relays are certified components. Always use the manufacturer's safety manual and calculate the full PL/SIL value — do not assume the device alone achieves the required PL. The final PL depends on the complete safety function: sensor + safety relay + actuator.

PL_sys = f(MTTFd, DCavg, CCF, Architecture category) — per ISO 13849-1 Annex K

Input

Safety function type iSelect the primary safety function to be implemented.

Required PLr iRequired Performance Level from risk assessment.

Sensor channels available iNumber of independent switch/sensor channels available. Two channels required for PLd and above.

Reset type iManual monitored reset required for most safety applications. Automatic reset only for process applications with no access.

Result

Recommended relay type —

Minimum architecture category —

Output contacts required —

External device monitoring (EDM) —

Example devices —