Figs. 2,383 and 2,384.—Elevation and plan of General Electric horn gaps and operating stand for high voltage arresters.
In construction, the aluminum arrester consists essentially of a system of nested aluminum cup shaped trays, supported on porcelain and secured in frames of heated wood, arranged in a steel tank.
The system of trays is connected between the line and ground, and between line and line, a horn gap being inserted in the arrester circuit which prevents the arrester being subjected to the line voltage except when in action.
The electrolyte is poured into the cones and partly fills the space between the adjacent ones. The stack of cones with the electrolyte between them is then immersed in a tank of oil. The electrolyte between adjacent cones forms an insulation. The oil improves this insulation and prevents the evaporation of the solution.
Fig. 2,385.—Cross section of General Electric aluminum (electrolytic) lightning arrester.
A cylinder of insulating material concentric with the cone stack is placed between the latter and the steel tank, the object being to improve the circulation of the oil and increase the insulation between the tank and the cone stack. The arrester, as just described consists of a number of cells connected in series.
Ques. Of what does a single cell consist and what are its characteristics?
Ans. It consists of two of the cone shaped aluminium trays or plates and an electrolyte, which forms a condenser that will stand about 350 volts before breaking down. When this voltage is exceeded the cell becomes a fairly good conductor of electricity, but as soon as the voltage drops its resistance again resumes a very high value.