Asea Brown Boveri Ag

Nicholas De Kock

Ingo Herbst

A partial-discharge measuring device (3) which detects partial discharges in a gas-insulated, metal-enclosed, high-voltage system. The device includes an annular-gap antenna (6) arranged on the inner surface of the metal enclosure (1), a coaxial measuring cable (7) guided to a measuring instrument, and a tapering adaptor conductor (8) which connects the annular-gap antenna (6) and the coaxial measuring cable (7). The annular gap (9) of the antenna is determined by a plate-shaped electrode (10) which is inserted in an electrically insulated fashion into an opening (5), provided for a flanged attachment (4) in the metal enclosure (1). The adaptor conductor (8) includes an inner conductor, which supports the electrode (10), and is guided onto the shielded conductor (14) of the measuring cable (7), and an outer conductor which is guided onto the shield (15) of the measuring cable (7). The flanged attachment (4) tapers in the shape of a funnel between the opening (5) and the flange (16), and forms with its inner surface a first portion of the outer conductor. The partial-discharge measuring device (3) is of a simple and compact design and can be produced economically. In the UHF region, which is important for an accurate measurement of partial discharges, its transfer function exhibits at frequencies between 300 MHz and 1.8 GHz a portion which is high and flat. The measuring accuracy and sensitivity of the partial-discharge measuring device (3) are therefore particularly high in this frequency region.

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Winterthur, Switzerland

Nicholas De Kock