Stop Category 0
One of the stopping classes defined in IEC 60204-1: power to the machine actuators is removed immediately and motion ends in an uncontrolled manner. Braking is provided mechanically or by a separate energy source, not by motor torque; it is the fastest but harshest form of stopping.
In Category 0 the logic is simple: the control voltage is cut, the contactors drop out, the motor is left free. It is the solution that is easiest to verify electrically, because the removal of power is the stop itself; it does not depend on software or on the driver working correctly.
The price is mechanical. In a hoisting movement the motor torque disappears instantly, so the load can drop a short distance until the spring-applied brake engages; in horizontal movements, inertia causes swinging and sliding. The rope, hook and chassis carry the load of this sudden deceleration.
- Because it is based on removing power, it is inherently robust against electronic faults.
- The brake is expected to be of the independent, de-energised-holding type (spring-applied, electrically released).
- With frequently repeated starts and stops it accelerates mechanical wear.
A radio remote control set with relay outputs behaves, by its nature, very close to Category 0: the contact opens, the contactor coil drops out, the motor stops. Whether this behaviour is sufficient for your machine is decided by risk assessment.
The context in which this term is used: Wireless remote control installation: pairing, relays, safety