Measuring effective impedance of capacitor from generator frequency - by using square-wave generator to eliminate residual capacitances

摘要

The method overcomes the problems of capacitive components not influenced by the measurement parameter and of oscillator amplitude stabilisation. It gives information concerning the effective impedance component rather than just the apparent impedance. This is achieved by using a square wave generator. For measurement of the thickness of insulating layers on insulated metal bodies an earthed electrode is attached to the insulation so as to form an auxiliary capacitor with the metal body which is connected in series with the measurement capacitor. The capacitance is derived from a voltage measured against time. The method is applicable where the capacitor is used as a distance measurement transducer or for measuring the dielectric constant of the medium contained in the capacitor.