Air current monitor for power transformer - has blades on shaft parallel to flow balanced by spring operating cam (NL 2.5.77)

摘要

The air current monitoring system is installed in power transformers or chokes subject to forced draught cooling. The monitoring device rotates at a speed which is little affected by the dust deposits from the cooling air. The monitor consists of blades (1) on a hub (2) on a shaft (3) rotating in a housing. The shaft axis is parallel to the direction of flow of the air. The torque exerted on the blades is balanced by a coil spring (6). The blades are coupled to a cam (11) which actuates a switch (14) when rotated. The cam has a projecting pin (15). Together with the fixed stop on the housing it determines the starting and finishing position of the cam and the blades.