This term is not used very often. It refers to an emergency stop circuit with electromechanical components only.
Until the late 1980s all safety-related control functions were achieved with electromechanical switchgears.
However today we are using all kinds of electronic and microprocessor-controlled safety devices, so a clarification concerning how an emergency stop should function became necessary.
Emergency switching off is different from emergency stop in two ways:
- It is always in stop category 0 - Immediate disconnection (see image)
- It must use electromechanic equipment only (no electronics and software allowed)
Normally, the only emergency switching off device on machinery today is the main switch. If it is meant for use in case of emergency, then it must be coloured red and yellow. If the main switch is not red and yellow, then it must not be switched off in case of emergency, as this could prevent the braking of hazardous movements for example.