Standard Test Methods for Measurement of Energy and Integrated Charge Transfer Due to Partial Discharges (Corona) Using Bridge Techniques

Importancia y uso:

5.1 These test methods are useful in research and quality control for evaluating insulating materials and systems since they provide for the measurement of charge transfer and energy loss due to partial discharges (4-6).

5.2 Pulse measurements of partial discharges indicate the magnitude of individual discharges. However, if there are numerous discharges per cycle it is occasionally important to know their charge sum, since this sum is related to the total volume of internal gas spaces that are discharging, if it is assumed that the gas cavities are simple capacitances in series with the capacitances of the solid dielectrics (7 and 8).

5.3 Internal (cavity-type) discharges are mainly of the pulse (spark-type) with rapid rise times or the pseudoglow-type with long rise times, depending upon the discharge governing parameters existing within the cavity. If the rise times of the pseudoglow discharges are too long, they will evade detection by pulse detectors as covered in Test Method D1868. However, both the pseudoglow discharges irrespective of the length of their rise time as well as pulseless glow are readily measured either by Method A or B of Test Methods D3382.

5.4 Pseudoglow discharges have been observed to occur in air, particularly when a partially conducting surface is involved. It is possible that such partially conducting surfaces will develop with polymers that are exposed to partial discharges for sufficiently long periods to accumulate acidic degradation products. Also in some applications, like turbogenerators, where a low molecular weight gas such as hydrogen is used as a coolant, it is possible that pseudoglow discharges will develop.

Subcomité:

D09.12

Referida por:

D1868-24, D1711-24B, D2275-22

Volúmen:

10.02

Número ICS:

17.220.20 (Measurement of electrical and magnetic quantities)

Palabras clave:

bridge circuits; bridge techniques; capacitance increase; charge-voltage-trace bridge; corona; discharge energy; discharge inception level; energy; harmonics; integrated charge transfer; internal discharges; ionizing voltage; loop trace; partial discharges; pseudoglow discharge; pulse discharge; pulseless-glow discharge; pulse measurements; solid insulating materials; surface discharge; transformer-ratio-arm bridge ;