Measurement of inductance and effective capacitance of a standard air capacitor

Conclusions

• 1. The effective capacitance of standard air capacitors, owing to their self-inductance produced by their construction, is a rising function of frequency determined by Eq. (1).

• 2. The capacitor inductances are so small that at audio-frequencies their effective capacitance is virtually equal to their static capacitance.

• 3. An error in the computed value of the effective capacitance not exceeding hundredths of a percent at high frequencies can be obtained provided that the capacitor's inductance is known with an error of 10% or higher [1] and it is, therefore, only necessary to know the nominal inductance of a capacitor of a given type and its nominal capacitance in order to determine its effective capacitance. It is unnecessary to measure the inductance of each model.

• 4. The frequency error can be reduced by using the near-end connections of the capacitor.

• 5. The inductance of the capacitors remains constant right up to the capacitor's resonant frequencies and can, therefore, if required, be measured by a resonance method, in particular by means of a Q-meter.

• 6. Standard air capacitors, both of Soviet and foreign makes, can be used in metrological and testing practice for checking working capacitors, capacity-measuring sets and similar instruments up to frequencies of several megahertz, depending on their nominal capacitance and the tolerated error in checking.