Advanced commissioning
6.11 Safe Torque Off (STO) safety function
Converter with the control units CU240D-2
152
Operating Instructions, 04/2018, FW V4.9 SP10, A5E34262100B AF
Application examples for the STO function
The STO function 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 through friction. STO does not shorten the
run-on of machine components with high inertia.
Examples
Possible solution
When the Emergency Stop button is pressed, a
stationary motor should not unintentionally start.
•
Wire the Emergency Stop button to a fail-
safe input of the inverter.
•
Select STO via the fail-safe input.
A central emergency stop button must prevent the
unintentional acceleration of several motors that
are at a standstill.
•
Evaluate the Emergency Stop button in a
central control.
•
Select STO via PROFIsafe.
6.11.2
Precondition for using STO
Prerequisite for STO use
In order to use the STO safety function, the machine manufacturer should have already
performed a risk assessment, e.g. in compliance with EN ISO 1050, "Safety of machinery -
Principles of risk assessment". The risk assessment must confirm that the inverter is
permitted for use in accordance with SIL 2 or PL d.
6.11.3
Commissioning STO
6.11.3.1
Commissioning tools
We recommend that you commission the safety functions using the STARTER or Startdrive
PC tool.
Commissioning tools (Page 81)
6.11.3.2
Safety functions password
What is the purpose of the password?
The password protects the settings of the safety function from being changed by
unauthorized persons.
Do you have to assign a password?
You do not have to assign a password.
The machine manufacturer decides whether or not a password is required.