Determining a dielectric property of a capacitor

摘要

An apparatus for determining at least one dielectric property of a capacitor arrangement, and especially for capacitive examination of a moving elongated test subject such as yarn. It contains an alternating signal generator for applying an electric alternating signal to the capacitor arrangement. The capacitor arrangement is uncoupled from the alternating signal generator by means of an amplifier in such a way that it does not relevantly influence the basic frequency and the signal shape of the applied alternating signal. Detection means detect an electric measuring variable of an electric signal tapped from the capacitor arrangement. The alternating signal generator is set up in such a way that at least one of the basic frequency and the signal shape of the applied alternating signal can be changed.

主权项

1. An apparatus for the capacitive examination of a moving elongated test subject, comprising:
a capacitive measuring circuit having a measuring capacitor for receiving the test subject and a reference capacitor that is not passed-through by the test subject, the measuring capacitor and the reference capacitor connected in series with respect to each other and jointly forming a capacitive voltage divider, an electric alternating signal generator for applying a first electric alternating signal with a specific basic frequency and a specific signal shape to the measuring capacitor, and for applying a second electric alternating signal that is substantially identical to the first electric alternating signal but is phase-shifted in relation to the first electric alternating signal by 180° to the reference capacitor, the capacitive measuring circuit uncoupled from the alternating signal generator such that the capacitive measuring circuit does not significantly affect the basic frequency and the signal shape of the applied alternating signals, and detection means for detecting at least one electric measuring variable of an electric signal tapped from the measuring capacitor, the alternating signal generator configured so that at least one of the basic frequency and the signal shape of the applied alternating signals are changeable, and at least one of the phase position and the amplitude of the applied alternating signals are changeable.