An electrical plug connector for connection of an electrical cable (2) to an apparatus, such as a sensor or an actuator, includes a housing (3) having a contact mount (5) holding a variety of contacts (4), and an electronics circuit (6) having at least one light-emitting element, LED (7) and being electrically connected to the contacts (4). The status of whether the LED (7) is illuminated or not can be identified particularly well, even in the presence of strong external incident light, by the housing (3) being composed of a thermoplastic material, at least in the area of the LEDs (7), and including an additive (8) that influences transparency and color for reducing the transparency of the thermoplastic material.

An electronic switching device, which operates without contact, includes a single sensor element (1), a clock generator, which can be provided internally or which can be connected externally, an evaluation circuit (2), and an electronic or electromechanical switch (3), which is provided on an output side. The evaluation circuit (2) includes diversity processing units (4, 5), and a checking unit (6), wherein an output signal of the sensor element (1) is delivered in succession to the processing units (4, 5), and that output signals of the processing units (4, 5) are checked for consistency by the monitoring unit (6). Advantageously, with only a single sensor element (1), category 4 of EN 954-1 or safety level SIL 3 of EN 61508 requirements can be achieved.

A device for measurement and detection of the level of a medium in a container with a sensor element, with a reference element and an electrical circuit which contains at least one AC voltage source and an evaluation unit, the sensor element and the reference element being arranged such that the medium to be measured or detected influences the impedance between them. The capacitive level measurement and detection device has an AC voltage source that supplies a high-frequency voltage or a voltage with high frequency voltage portions. The circuit which has the AC voltage source, the sensor element and the reference element has an impedance which is as low as possible. The electrical circuit can have an amplifier, a timer, a pulse shaper, a first synchronous rectifier, a first I/U converter, a microcontroller, a reference impedance, a second synchronous rectifier and a second I/U converter.

A capacitive sensor with at least one reference impedance and at least one measuring condenser (5), with at least one electrical alternating signal source (6), with a current supply network as well as with an analysis unit (7) in which the reference impedance and the measuring condenser (5) are connected via the current supply network to the alternating signal source (6) and the analysis unit (7) in such a way that the charge and discharge currents of the reference impedance and the measuring condenser (5) can be analyzed--at least partially--by the analysis unit (7). The capacitive sensor avoids--at least partially--drawbacks in the known capacitive sensors in that the reference impedance can be tuned.

An electrical connector connects to a mating connector by a rotatable union nut that is axially displaceable on a contact carrier with a sealing element therebetween. Damage to the sealing element is prevented by a stop that limits the maximum path by which the union nut can be screwed onto the mating connector, such that when the union nut is screwed on, the elastic sealing element is intentionally compressed, but is not damaged or destroyed. A vibration guard can also be provided in the connection.