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 by electromechanical switchgear. Today however, we are using all kinds of electronic and even microprocessor-controlled safety devices, often even controlled by software. Today however, we are using all kinds of electronic and even microprocessor controlled safety devices, often controlled by software.
Emergency switching off is different from emergency stop in two ways:
- It is always in stop category 0
- 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 red and yellow. A black or gray main switch must not be switched off in case of emergency as this could prevent braking of hazardous movements.
The international standard for emergency stop devices is (EN) ISO 13850.