Safe Torque Off (Sto) - Siemens SIMATIC ET 200SP F-TM Equipment Manual

Safety functions integrated in the drive
5.1 Basic safety information
Operating voltage range
Operate input STO+ as intended with 19.2 to 28.8 V DC for the active enable or lower
5 V DC for the disable.
Connect the input STO- for enabling or disabling the connection to ground.
5.1.4.1

Safe Torque Off (STO)

Safe Torque Off (STO) is a safety function that directly stops torque- or force-producing
energy from being supplied to the motor. This function corresponds to Stop Category 0
according to EN 60204-1.
The F-TM ServoDrive complies with the definition of the STO function in IEC/EN 61800-5-2:
"The STO function prevents torque-producing energy from being supplied to the motor."
If the motor is still rotating when STO is selected, the motor will coast to a standstill.
Figure 5-2
Functional characteristics
Danger to life due to coasting down of the drive with STO
The Category 0 stop function according to EN 60204-1 (STO according to Safety
Integrated) means that the drives are not braked but instead coast down for an amount of
time corresponding to the kinetic energy.
• You must take this behavior into account, for example, in the logic for the protective
STO is a drive-specific function and must be wired individually for each drive.
The following applies when the "Safe Torque Off" function is selected:
● An unwanted startup of the motor cannot take place.
● The torque-producing energy supply to the motor is safely interrupted.
● An electrical isolation between the power unit and motor does not occur.
The stop function category 0 (selection of STO according to Safety Integrated) is only active
when selected at the STO terminals. In order to meet the requirements of an EMERGENCY
STOP in accordance with EN 60204-1, you need to ensure that the STO function at the STO
terminals in the system can only be deselected by means of conscious manual operation.
This prevents electrically driven machine components from restarting unintentionally.
36
Functioning of STO (A) when motor is at stopped and (B) when motor is rotating
WARNING
door interlock.
Equipment Manual, 02/2020, A5E47579503-AA
F-TM ServoDrive