Safe Torque Off (Sto) - Siemens SINAMICS S120 Function Manual

Safety Integrated basic functions

9.3 Safe Torque Off (STO)

The "automatic restart" function may not be used together with the safety functions
STO/SBC and SS1. The reason for this is that EN 60204 Part 1 (1998) in chapter 9.2.5.4.2
does not permit this (merely de-selecting a safety shutdown function must not cause the
machine to restart).
NOTICE
Components cannot be deactivated via p0105, for example, with activated Safety functions.
9.3 Safe Torque Off (STO)
General description
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 motor power supply.
When the function is selected, the drive unit is in a "safe status". The power-on disable
function prevents the drive unit from being restarted.
The two-channel pulse inhibit integrated in the Motor Modules / Power Modules 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
● The function is drive specific, that is, it must be commissioned individually on a drive-by-
● Enable of the function using parameters required.
● When the "Safe Torque Off" function is selected:
308
CAUTION
required.
drive basis.
– The motor cannot be started accidentally.
– The pulse disable safely disconnects the torque-generating motor power supply.
– The power unit and motor are not electrically isolated.
WARNING
Appropriate measures must be taken to ensure that the motor does not move once
the motor power supply has been disconnected ("coast down") (e.g. enable the "Safe
Brake Control" function with a vertical axis).
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
Drive Functions