A quality diagnostics system for lubricant/coolant fluid includes a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator. An inverter includes a plurality of power switches configured to supply an alternating current (AC) power to the motor for driving the rotor to rotate. A passageway conveys the lubricant/coolant fluid between the motor and the inverter. A lubricant quality sensor includes a set of sensor plates disposed along the passageway, an excitation source configured to apply an AC excitation voltage to a first sensor plate, and an electrical sensor configured to measure a response to the AC excitation voltage. A controller determines, based on a sensor signal from the electrical sensor, at least one of metal contamination and water contamination in the lubricant/coolant fluid.

A device for measuring a fill level of a liquid in a container with an ultrasonic sensor, wherein the ultrasonic sensor is arranged at the bottom end of a damping cup with a measuring tube, wherein the top area of the measuring tube has at least one inner ventilation hole and a cover assigned to the inner ventilation hole. The cover surrounds at least the upper end area of the measuring tube and itself has at least one outer ventilation hole, wherein at least one screen is present in the cover and is in contact with the cover at the top. The screen is in contact with the cover at the top and extends horizontally from the measuring tube as far as a side wall of the cover.

In a device for measuring a fill level of a liquid in a container with an ultrasonic sensor, wherein the ultrasonic sensor is arranged at the bottom end of a damping cup with a measuring tube, wherein the top area of the measuring tube has at least one inner ventilation hole and a cover assigned to the inner ventilation hole, which cover surrounds at least the upper end area of the measuring tube and itself has at least one outer ventilation hole, wherein at least one screen is present in the cover and is in contact with the cover at the top, it is provided that the screen which is in contact with the cover at the top extends horizontally from the measuring tube as far as a side wall of the cover. In addition at least four screens are provided between the one or more inner ventilation holes and the one or more outer ventilation holes, so that at least two air bubbles are trapped in the region of the screen when the device is in operation.

A quality diagnostics system for lubricant/coolant fluid includes a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator. An inverter includes a plurality of power switches configured to supply an alternating current (AC) power to the motor for driving the rotor to rotate. A passageway conveys the lubricant/coolant fluid between the motor and the inverter. A lubricant quality sensor includes a set of sensor plates disposed along the passageway, an excitation source configured to apply an AC excitation voltage to a first sensor plate, and an electrical sensor configured to measure a response to the AC excitation voltage. A controller determines, based on a sensor signal from the electrical sensor, at least one of metal contamination and water contamination in the lubricant/coolant fluid.

A quality diagnostics system for lubricant/coolant fluid includes a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator. An inverter includes a plurality of power switches configured to supply an alternating current (AC) power to the motor for driving the rotor to rotate. A passageway conveys the lubricant/coolant fluid between the motor and the inverter. A lubricant quality sensor includes a set of sensor plates disposed along the passageway, an excitation source configured to apply an AC excitation voltage to a first sensor plate, and an electrical sensor configured to measure a response to the AC excitation voltage. A controller determines, based on a sensor signal from the electrical sensor, at least one of metal contamination and water contamination in the lubricant/coolant fluid.