Abstract: State of a high voltage capacitor is monitored to detect partial discharge within the capacitor and approaching end-of-life of the capacitor. Partial discharge may be detected through an increased capacitance of the capacitor, and the resulting increase in the alternating current through the capacitor. Partial discharge may also be detected by presence of high frequency components in the current. Moreover, partial discharge may be detected through an increase in the internal pressure of the capacitor. When partial discharge is detected, a warning is generated, and the capacitor may be replaced in response to the warning. Periodic or random checks of the capacitor state, as indicated by the current or pressure, may also be performed. Warnings may be, for example, visual and/or audio, and may be transmitted to remote locations by radio frequency, infrared signals, or via power lines.

Abstract: State of a high voltage capacitor is monitored to detect partial discharge within the capacitor and approaching end-of-life of the capacitor. Partial discharge may be detected through an increased capacitance of the capacitor, and the resulting increase in the alternating current through the capacitor. Partial discharge may also be detected by presence of high frequency components in the current. Moreover, partial discharge may be detected through an increase in the internal pressure of the capacitor. When partial discharge is detected, a warning is generated, and the capacitor may be replaced in response to the warning. Periodic or random checks of the capacitor state, as indicated by the current or pressure, may also be performed. Warnings may be, for example, visual and/or audio, and may be transmitted to remote locations by radio frequency, infrared signals, or via power lines.

Abstract: A high voltage capacitor includes multiple conductive strips on each side of a dielectric layer. The conductive strips on one side of the dielectric layer partially overlap conductive strips on the opposite side of the dielectric layer, in effect forming a series combination of subcapacitors. Insulating layers may overlay the conductive strips, sandwiching the strips between one of the insulating layers and the dielectric layer. To decrease the magnitude of the electric field between adjacent conductive strips on the same side of the dielectric layer, the gaps between the adjacent strips are filled with a dielectric liquid during the manufacturing process. The dielectric liquid may be, for example, aromatic oil, silicone oil, mineral oil, synthetic oil, a mixture of different oils, or a mixture of oil or oils with another substance. The resulting decrease in the magnitude of the electric field within the gaps reduces partial discharge in the capacitor.