Series vacuum interrupters with grading capacitors integrated in a molded switch housing

A high voltage (HV) switching device, comprising:

• two or more switching modules connected in series, each switching module comprising:
• a vacuum interrupter (VI) having a fixed contact and a moving contact;
• an insulating sleeve disposed around the VI;
• an insulating housing of insulating material molded around the VI and the sleeve;
• and
• a pair of grading capacitors molded in the insulating housing and comprising a first grading capacitor and a second grading capacitor, each grading capacitor comprising an inner and an outer electrode that are concentric and an insulating member of insulating material disposed between the inner electrode and the outer electrode, wherein a capacitance of the first grading capacitor is substantially equal to a capacitance of the second grading capacitor,
• wherein the inner electrode and outer electrode of both grading capacitors are molded out of conductive plastics,
• wherein each of the inner electrode and the outer electrode of both grading capacitors extends in an arc around the VI in a plane normal to a VI axis extending longitudinally through a central region of the VI and the arc section extends in the VI axis direction for a specified length,
• wherein an arc angle of the arc for each of the inner electrodes and the outer electrodes is less than 180° wherein a gap exists between arc ends of the inner and outer electrodes in each grading capacitor,
• wherein the inner electrode and outer electrode of each grading capacitor share an axis with the VI but are offset axially,
• wherein the inner electrode of both grading capacitors also includes a shield section attached to the arc,
• wherein the shield section of the inner electrode extends 360° around the VI and provides shielding of an external triple point of the VI,
• wherein the shield section of the inner electrode of the first grading capacitor is placed between the inner electrode of the second grading capacitor and the moving contact of the VI and wherein the shield section of the inner electrode of the second grading capacitor is placed between the inner electrode of the first grading capacitor and the fixed contact of the VI, and
• wherein the VI further comprises a fixed contact stem attached to the fixed contact, a moving contact stem attached to the moving contact, the inner electrode of the first capacitor and the outer electrode of the second capacitor are galvanically connected to the VI moving stem, while the inner electrode of the second capacitor and the outer electrode of the first capacitor are galvanically connected to the VI fixed stem, whereby the first and second grading capacitors are connected in parallel with the VI contacts;
• wherein each switching module has a first and a second terminal and wherein each pair of adjacent switching modules are connected in series with the second terminal of one of the pair of switching modules connected to the first terminal of an other of the pair of switching modules, each switching module has a same total capacitance of the pair of grading capacitors across an associated VI and, when the HV switching device is in an open position and high voltage is applied across the HV switching device, substantially an equal portion of an applied high voltage exists across each of the switching modules of the HV switching device.

A high voltage (HV) switching device, comprising:

• two or more switching modules connected in series, each switching module comprising:
• a vacuum interrupter (VI) having a fixed contact and a moving contact;
• an insulating sleeve disposed around the VI;
• an insulating housing of insulating material molded around the VI and the sleeve;
• and
• a pair of grading capacitors molded in the insulating housing and comprising a first grading capacitor and a second grading capacitor, each grading capacitor comprising an inner and an outer electrode that are concentric and an insulating member formed of the insulating material disposed between the inner electrode and the outer electrode, wherein a capacitance of the first grading capacitor is substantially equal to a capacitance of the second grading capacitor,
• wherein each switching module has a first and a second terminal and wherein each pair of adjacent switching modules are connected in series with the second terminal of one of the pair of switching modules connected to the first terminal of the other of the pair of switching modules, all the switching modules have a same total capacitance of the pair of grading capacitors across an associated VI and, when the HV switching device is in an open position and high voltage is applied across the HV switching device, substantially an equal portion of an applied high voltage exists across each of the switching modules of the HV switching device.