Commissioning Manual
104 6FC5397-4EP10-0BA8, 07/2018
In conjunction with a machine function or in the event of a fault, the "Safe Torque Off" (STO) function is used to safely
disconnect the torque-generating energy feed to the motor.
When the function is selected, the drive unit is in a "safe status". The switching on inhibited function prevents the drive unit
from being restarted.
The two-channel pulse suppression function integrated in the module is a basis for this function.
Functional features of "Safe Torque Off"
● This function is integrated in the drive; this means that a higher-level controller is not required.
● The function is drive-specific, i.e. it is available for each drive and must be individually commissioned.
● When the "Safe Torque Off" function is selected, the following applies:
– The motor cannot be started accidentally.
– The pulse suppression safely disconnects the torque-generating energy feed to the motor.
– The power unit and motor are not electrically isolated.
● By selecting/deselecting STO, in addition to the fault messages, the safety messages are also automatically withdrawn.
The STO function can be used wherever the drive naturally reaches a standstill due to load torque or friction in a sufficiently
short time or when "coasting down" of the drive will not have any relevance for safety.
Note
Closing delay of the holding brake
The closing signal (low level) of the holding brake is output 30 ms after the STO is triggered.
Preconditions for using the STO function
When use the STO function, the following preconditions should be fulfilled:
● Each monitoring channel (STO1 and STO2) triggers safe pulse suppression with its switch off signal path.
● If a motor holding brake is connected and configured, the connected brake is not safe because there is no safety function
for brake, such as safe brake.
Behaviors of the STO function
High level High level Safe The servo motor can normally run when you power on the servo
The servo drive starts up normally but the servo motor cannot run.
Alarm occurs and servo motor coasts down.
Alarm occurs and servo motor coasts down.
For more information about the STO function, see the SINUMERIK 808D ADVANCED Function Manual.
Connecting the holding brake - X7 (feed drive only)
Holding brake (drive side)
Brake interfaces
B+: + 24 V, motor brake voltage positive
Phase B- B-: 0 V, motor brake voltage negative
Maximum cable cross-section: 1.5 mm
2
Input voltage tolerance: 24 V ± 10%
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