Abstract: A device for monitoring a supply line of a frequency converter-fed electrical machine is used to predict failure, wear and/or ageing of the electrical supply line. The electrical supply line is designed and installed to connect an electrical machine in an industrial machine or plant or in a land or aircraft vehicle to a frequency converter. The frequency converter is designed and intended to supply the electrical machine with a single-phase or multi-phase alternating voltage with preferably variable voltage amplitude and pulse duration through the electrical supply line, wherein a change in pulse duration and/or voltage amplitude of the alternating voltage serves to change a speed or torque of the electrical machine. The frequency converter is set up and intended to provide each phase of the AC voltage as a sequence of square-wave pulses with a high edge steepness for feeding the electrical machine.

Abstract: A photoelectric barrier apparatus is provided, which comprises a transmitting device for light, a reflecting device and a receiving device for reflected light with at least one photodetector, wherein the at least one photodetector is arranged at an acute angle to an optical axis, wherein the at least one photodetector has a receiving face for light and the acute angle lies between the optical axis and a normal of the receiving face.

Abstract: A photoelectric barrier apparatus is provided, which comprises a transmitting device for light, a reflecting device and a receiving device for reflected light with at least one photodetector, wherein the at least one photodetector is arranged at an acute angle to an optical axis, wherein the at least one photodetector has a receiving face for light and the acute angle lies between the optical axis and a normal of the receiving face.