Safety concept

The drive unit is supposed to be able to perform the safety subfunction "Safe Torque Off" according to EN 61800‑5‑2:

• The drive unit can be connected to an external safety controller or safety relay. This external safety controller/safety relay disconnects the safety-related STO input via a 2-pole 24 V switching signal (sourcing/sinking) when a connected command device (e.g. emergency stop button with latching function) is activated. This activates the STO function of the drive unit.
• An internal, dual-channel structure with diagnostics prevents the generation of pulse trains at the power output stage (IGBT).
• Instead of galvanic isolation of the drive from the supply system by means of contactors or switches, the disconnection of the STO input described here safely prevents the control of the power semiconductors in the output stage. The rotary-field generation for the respective motor is deactivated even though the line voltage is still present.
• When the STO safety subfunction is activated, the PWM signals generated by the drive unit are interrupted by the STO circuit and not transmitted to the IGBTs.
• If the STO function detects a discrepancy between both channels, the PWM signals are inhibited. The inhibit can be revoked by a 24 V reset, or by a device reset if F_STO_P1 and F_STO_P2 are not controlled with 24 V.
• The STO safety subfunction can be activated externally e.g. via an external safety device via the STO input.