Option description  11
Option description
Contents of this chapter
This chapter describes the Safe torque off (STO) function of the drive and inverter 
modules and lists the indications and response times of the Safe torque off function.
Description
The Safe torque off function can be used, for example, to construct safety or supervision 
circuits that stop the inverter in case of danger (such as an emergency stop circuit). 
Another possible application is a prevention of unexpected start-up function that enables 
short-time maintenance operations like cleaning or work on non-electrical parts of the 
machinery without switching off the power supply.
When activated, the Safe torque off function disables the control voltage of the power 
semiconductors of the inverter output stage. This prevents the inverter from generating the 
torque required to rotate the motor. If the motor is running when Safe torque off is 
activated, it coasts to a stop.