Option Description; Contents Of This Chapter; Description - ABB ACS800 Series Application Manual

Option description 11

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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.