STO safety concept

• The device is characterized by the optional connection of an external safety controller/safety relay. This external safety controller/safety relay disconnects the safety-related STO input via a two-pole 24 V switching signal (e.g., sourcing/sinking) when a connected command device (e.g., emergency stop button with latching function) is activated. This activates the STO function of the device.
• An internal structure with diagnostics prevents the generation of pulse trains at the power output stage (IGBT).
• If the internal diagnostics detects a fault, the PWM signals are permanently switched off.
• Instead of a 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 activation 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.
• If the internal diagnostics of the STO circuit detects a discrepancy between the two channels, the PWM signals are locked, i.e. STO is activated. This locking requires a reset by switching the DC 24 V supply voltage of the device or the DC 24 V switching signal at the STO input F_STO_P off and back on.