Verification Procedure for High Voltage Standard Capacitors

What is a high-voltage capacitor?

Calibrations at frequencies from 50-400 Hz are avail- able over a more limited voltage range. The service for high-voltage capacitors provides measurements of capacitance and dissipation factor at applied voltages ranging from 100 V to 170 kV at 60 Hz depending on the nominal capacitance.

What voltage can a capacitor be calibrated at?

Calibrations at frequencies from 50–400 Hz are available over a more limited voltage range. The service for high-voltage capacitors provides measurements of capacitance and dissipation factor at applied voltages ranging from 100 V to 170 kV at 60 Hz depending on the nominal capacitance.

What is the calibration service for voltage transformers and high-voltage capacitors?

The National Institute of Standards and Technology (NIST) calibration service for voltage transformers and high-voltage capacitors is described. The service for voltage transformers provides measurements of ratio correction factors and phase angles at primary voltages up to 170 kV and secondary voltages as low as 10 V at 60 Hz.

How do you measure the ratio of two capacitors?

The ratio of the two capacitors in eq (2) can be measured using the circuit of figure 2. The measurement of a voltage transformer or a capacitor both involve the measurement of the ra- tio of two standard capacitors. The measurement of capacitors will be discussed below followed by a discussion on the measurement of voltage trans- formers.

What is the difference between voltage transformer calibration and capacitance calibration?

The voltage transformer calibration is of the direct null type, and the capac- itor calibration is of the comparative null type. In other words, the accuracy of the capacitance mea- surements ultimately depends on the uncertainty in assigning a value to a standard capacitor.

How are capacitors measured?

Capacitors are invariably measured by balancing the unknown capacitor against a known standard using some type of bridge arrangement. There are a variety of such bridges described in the literature . The one most used in high-voltage applications in the last 60 years is the Schering bridge (fig. 1).