Siemens SIMOTICS S-1FK2, Operating Instructions Manual

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4.2 Basic Functions
4.2.1 Safe Torque Off (STO)
Overview
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Safe Torque Off (STO) is a safety function that
immediately ensures that torque or force-gen‐
erating energy is not fed to the motor. This
function corresponds to stop category 0 to
EN 60204-1.
If the motor is still rotating when STO is selec‐
ted, then it coasts down to standstill.
Functional features
The switching on inhibited prevents an automatic restart after deselection of STO and therefore
satisfies the requirements of EN 60204-1. Consequently, the STO function prevents an
electrically-driven machine component from restarting.
Note
There is no galvanic isolation between motor and converter.
The STO function can be selected via PROFIsafe and/or the fail-safe digital input (F-DI).
STO is a drive-specific function that must be put into operation individually for each drive.
Applications
Applications include all machines and systems with moving axes (e.g. conveyor technology,
handling).
STO is suitable for applications where the motor is already at a standstill or will come to a
standstill in a short, safe period of time as a result of friction.
Safety functions integrated in the drive
4.2 Basic Functions
SINAMICS S210 servo drive system
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Operating Instructions, 12/2017, A5E41702836B AA