Glossary · Automation fundamentals, platforms and components
Standstill
Also known as: Zero speed
German: Stillstand
In drive and machine technology, standstill is the state in which a moving part or axis has stopped, detected by speed or position falling below a defined threshold for a defined time. Standstill monitoring is used, for example, to release guard locking or to supervise a stopped axis.
- Automation components
- Functional safety
In one sentence
Standstill is the state in which an axis or moving part has stopped, detected when speed stays below a threshold for a set time.
Example
The guard locking of the lathe releases only after the safe standstill monitor has confirmed that the spindle speed is below 2 rpm.
How it applies
- Engineering: Standstill detection uses encoders, drive feedback or dedicated standstill monitors. Thresholds and filter times must avoid both false releases and nuisance stops.
- Safety: When standstill is part of a safety function, for example releasing Guard locking on a Protective door, it must be detected by safety-rated means with the required PL or SIL. Standard drive status bits are not sufficient for this.
- Documentation: Distinguish in manuals between an axis at standstill with power (for example Safe Operating Stop (SOS)) and an axis without torque (Safe Torque Off (STO)), and state what the operator can safely do in each case.
Standstill vs. de-energized
Standstill means no motion; the drive may still hold position with full torque and can move again. A de-energized or torque-free state means no torque is produced, but a load may still move under gravity or inertia.