Buchholz Relay | Instruction Manual No. 5

In this fifth edition of instructions, we bring you a new accessory for the electrical transformer: the Buchholz Relay. This apparatus is placed in the oil duct between the transformer tank and the oil expansion tank. The operation of this device is based on the fact that any deterioration that occurs inside the tank will give rise to the development of gas due to the decomposition of solid and liquid insulation under the action of heat. The Buchholz Relay consists of a container with an inlet and an outlet mouth, and two diametric sights, closed with an airtight lid. It also features oil and gas purge straps, function testers and terminal box. The detector device itself is made up of two scales with a float system, one upper and one lower. If a minor malfunction occurs, gas bubbles develop and enter the Buchholz container, thus causing the first balance to fall, then the alarm circuit is activated. In the event of a serious deterioration, there is a tumultuous formation of gas that causes a violent push of oil, which causes the inner balance to act and then closes the disengagement circuit. The relay indicates the following defects: short circuits between the magnetic plates of the transformer core, arcing due to interruption of the single-phase circuits, prolonged and excessive overloads, and oil leaks.