Safe disconnection function (STO)

The safe disconnection function locks the output stage of the inverter. This prevents a torque-generating rotating field from being connected to the motor. The motor coasts to a stop.

Restarting the motor is possible only if:

• A voltage of 24 V is present between STO+ and STO-.
• All fault messages are acknowledged.

Using the STO function makes it possible to integrate the drive into a safety system in which the STO function must be fully compliant.

The STO function makes the use of electro-mechanical protection with self-checking auxiliary contacts for implementing safety functions redundant.