Glossary · System coordination, integration and orchestration
Controlled stop
Also known as: controlled stopping
German: Gesteuerter Stopp
In IEC 60204-1, a controlled stop is the stopping of machine motion by reducing the command signal to zero once the stop signal has been recognized by the control, while power to the machine actuators is retained during the stopping process.
- System integration
- Standards
- Functional safety
In one sentence
A controlled stop brings machine motion to a halt under control of the drives, with power to the actuators retained while stopping.
Example
When the operator presses Stop, the servo drives of a winder decelerate along a ramp to standstill instead of coasting, and only then may power be removed.
How it applies
- Engineering: IEC 60204-1 stop categories 1 and 2 are controlled stops; stop category 0 is an uncontrolled stop by immediate removal of power. The choice of category for each stop function follows from the risk assessment.
- Safety: A controlled stop depends on the drives and control working correctly. Where it serves as a safety function, it must be designed with the required integrity, and the power removal after standstill (as in Stop category 1) must be ensured.
- Documentation: Manuals should state which stop category each stop device triggers and give stopping times (see Stopping time) only where they have been measured.
Controlled stop vs. coordinated stop
A controlled stop is defined per machine by how its actuators are stopped. A Coordinated stop is a line-level function that stops several machines in a defined order; each machine may use a controlled stop within it.