Power Electronics SD750FR, Hardware And Installation Manual

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SD750FR POWER ELECTRONICS
62
CONTROL CONNECTION
EN
STO - Safe Torque Off
The STO function is defined as: Power, that can cause rotation, is not applied to the motor. The frequency
converter will not provide energy to the motor, which can generate torque.
For three-phase asynchronous motor, that means to stop three-phase power supply to the stator.
This function corresponds to a Category 0 Emergency Stop according to IEC 60204-1. When the drive
is running and the STO function is applied, the motor will freely stop by its own inertia.
By using this function, the user can safely carry out cleaning, maintenance or emergency work on non-
electric parts of the equipment, without having to disconnect the power supply. In case STO safety
function is not used, user must connect the corresponding terminals.
Based on a study of each application and risk assessment, the designer should define the required safety
function and safety level.
CAUTION
The STO safety function does not disconnect nor the main neither the auxiliary power supply.
With STO function the drive disconnects the motor power supply. To carry out electrical
maintenance tasks, isolate the drive. Particular care must be taken with the active conductors
inside the drive.
Failure to do so could result in damage to equipment and personnel.
Do not use the STO function as a normal drive stop.