Special Features and Functions of Safety Relays

A key benefit of safety relays is their ability to specialize. They have a clear, self-contained task to fulfill, so specific customer requirements have led to a wide range of safety relays with particular functions and features: these include devices with muting function, with safe monitoring of speed, standstill and monitored disconnection, as well as safety relays with special properties for the Ex area. The examples below illustrate some of these functions.

Muting function
The muting function is used to automatically and temporarily suspend a safety function implemented via a light curtain or laser scanner for a particular purpose. A muting function is frequently used to transport material into and out of a danger zone.


Safety relays for the Ex area
Some of the most hazardous plant and machines are those that manufacture, transport, store or process dust, flammable gases or liquids. Explosive compounds may be produced during these processes, which could present a danger beyond the immediate environment. Potentially explosive atmospheres like these require special devices, on which electrical sparking on contacts is excluded. Such safety relays must provide an intrinsically safe output circuit and volt-free contacts for potentially explosive areas. These devices are approved for Ex area II (1) GD [EEx ia] IIB/IIC.