Abstract: Arc fault detection devices and methods are described current between a source and a load is periodically measured. A variance of the periodically measured current values is derived and an arc fault can be detected abased on the derived variance. A variance interval signal can be incremented based on the derived variance increasing above a threshold level and a low pass filter arranged to detect an arc based on the incremented variance interval signal.

Abstract: Arc fault detection devices and methods are described current between a source and a load is periodically measured. A variance of the periodically measured current values is derived and an arc fault can be detected abased on the derived variance. A variance interval signal can be incremented based on the derived variance increasing above a threshold level and a low pass filter arranged to detect an arc based on the incremented variance interval signal.

Abstract: An electric machine, in particular an electric motor, comprising a stator and a rotor, which are separated from each other by an air gap, wherein a measuring coil unit comprising a number of measuring coils which are adjacent to each other is arranged in the air gap. The electric machine is characterised in that the measuring coils are arranged one behind the other in the axial direction in the air gap. The invention further relates to a measuring coil unit which can be inserted in an air gap of an electric machine of this type, and a method for determining operating parameters of an electric machine which has a measuring coil unit of this type.

Abstract: A measuring instrument has a measuring configuration and a measuring circuit. The measuring circuit determines the capacitance of a capacitor and the conductance of the measuring configuration, which is formed of a casing and a sensor element around which a mixture flows. The alcohol content of the mixture is determined therefrom. The measuring circuit has an oscillator and a control circuit connected upstream thereof. The measuring configuration, which is represented by the capacitor and the conductance, is a part of the oscillator, which oscillates within a measuring cycle at three different oscillator frequencies which are set by three different control voltages of the control circuit, and evaluated in a microcontroller. Component tolerances which influence the oscillator frequencies can thus be taken into account.

Abstract: An apparatus for ascertaining the alcohol content or the calorific value of a mixture containing alcohol and gasoline includes an electrically conductive housing through which the mixture flows and in which at least one physical parameter of the mixture is measured to produce a measurement. An electronic measuring circuit is disposed in the housing for evaluating the measurement. The housing has a wall with a part of the wall forming a first electrode of a capacitor. An intermediate plate is associated with the housing. An electrically conductive sensor element is secured in the intermediate plate and partly surrounded by the mixture. The electrically conductive sensor element forms a second electrode of the capacitor and forms an electrical connection between the second electrode and the measuring circuit.