Buchholz relay

Abstract

The invention relates to a Buchholz relay for monitoring the development of gas and the insulation liquid in liquid-filled high-voltage systems. Two floats which can be deflected and act on an electrical switching device are provided. Furthermore, a flow flap is provided which likewise acts on an electrical switching device. According to the invention, the electrical switching device comprises one or two immersion tubes in each of which separate magnetic switching tubes are provided. The immersion tubes extend in a perpendicular manner through the collection space of the Buchholz relay. Furthermore, a line is provided, the free end of said line ending in the Buchholz relay in the region of the flow flap, wherein the line can be subjected to the action of air or oil from the outside.

Description

Background technique

[0001] Buchholz relays (double-float relays) are long known protective devices for oil-insulated power transformers. Buchholz relays exhibit faults such as short circuits, shorted coils or lack of transformer oil. In the event of small deviations, such as the development of gas, this state is usually only signaled—a so-called “Buchholz alarm” is realized. In the event of a catastrophic fault, such as a short circuit, the transformer is switched off.

[0002] The known Buchholz relays are based on the fact that in oil-cooled transformers insulation faults or also severe overloading can lead to local overheating which leads to gas formation in the oil space of the transformer. Air bubbles accumulate in the upper part of the housing of the Buchholz relay and push against the oil present there in the normal state. In the event of a small fault, the float of the Buchholz relay drops due to gas formation and the contact closes, which notifies the fault. With...

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