What is an Emergency Stop?
An emergency stop is a safety device that allows an operator to immediately and safely shut down a machine or process in an emergency. Its purpose is to protect people, machinery and the environment from danger or damage.
An emergency stop is mandatory on most industrial machinery under the Machinery Directive and must comply with standards such as NEN-EN-ISO 13850 and NEN-EN-ISO 13849.
🧠 How does an emergency stop work?
- Mechanical operation
- Large red button, typically with a yellow background
- Press action (latching) immediately shuts the machine down
- Manual reset required (pull or twist)
- Electrical interruption
- Cuts power or signal via a safety relay or Safety PLC
- Can also halt pneumatic or hydraulic systems
- Safe response chain
- All hazardous motions stop immediately
- The machine stays disabled until the restart procedure is completed
🏭 Application in industrial environments
- Machines with moving parts: conveyors, robots, presses
- Control cabinets, HMI panels, operator consoles
- Mobile units or technical rooms
- Process lines with continuously running installations
Emergency stops must be clearly visible, easily accessible and placed in logical locations.
🔍 Requirements for emergency stop installations
| Aspect | Requirement per standard |
|---|---|
| Shape and colour | Red button with yellow background (ISO 13850) |
| Function | Shut the machine down immediately and completely |
| Latching | Yes, reset only possible after manual action |
| Redundancy | Dual paths required at higher PL or SIL levels |
| Diagnostics | Fault detection via safety relay or PLC |
An emergency stop is no substitute for preventive measures, but a complementary layer of protection.
🔐 Security considerations
- Part of a safety circuit including a safety relay or Safety PLC
- Lock-out Tag-out may be required for restart or maintenance
- Emergency stop functionality must be tested at commissioning and periodically thereafter
- A work permit is mandatory when shutting down for maintenance
- Documented in the RI&E and included in training and instructions
Tampering with or disabling emergency stop devices results in serious violations of the Working Conditions Act.
📌 In summary
The emergency stop is a critical safety device that enables the immediate shutdown of hazardous processes. It protects against injury and damage and is mandatory for virtually every industrial installation.