Festo Контроллеры двигателя CMMS-ST - Manual (Page 82)

4. Functional safety engineering
82 Festo.P.BE-CMMS-ST-G2-HW-EN 1008NH
4.2 Integrated function “STO”
Warning
The general safety functions do not provide protection from electric
shock but only from dangerous movements!
4.2.1 General remarks / description of “STO Safe Torque Off”
With the Safe Torque Off function (STO), the power supply to the motor is securely
interrupted through switching off of the end stage enable and of the power supply to the
output stage. The drive cannot generate torque or any force and so cannot make any
dangerous movements. If the STO function is activated with a moving drive, the motor
starts to run out in an uncontrolled manner after at most 3.2 ms. At the same time, the
automatic brake control is activated. If you use motors with a holding brake, each STO
disconnection places wear and tear on the brake. Therefore, use the SS1 function for STO
motors without holding brakes. A description of the SS1 function can be found in the next
chapter
4.3. Application examples for the STO function are manual actions during setup,
changeover and error resolution.
The use of the integrated solution offers several advantages:
Advantages - Fewer external components, e.g. circuit breakers
- Less cabling effort and less space required in the control
cabinet
- And so lower cost
Another advantage is the availability of the system. The integrated solution allows the
intermediate circuit of the controller to remain charged. This means no significant waiting
time when the system is restarted.