Ques. What are the features of the enclosed air break?
Ans. The switch is more compact than the open air break type, but pressure oscillations are caused on opening the circuit the same as with the open air break, and it is not desirable for heavy current.
Fig. 2,214.—Baum 35,000 volt, 200 ampere, double break pole type switch. While designed for disconnecting purposes only, it can break considerable amperage. The levers and couplings are fastened with tape pins. The control shaft coupling is adjustable to any angle, and the switch can be locked in the open or closed position. A removable wooden handle is supplied and the switch can be handled in any weather. The arms can be extended to hold fuse fittings, or dead end insulators in the event of a heavy strain, but it is preferable to have fuses on another structure as a precaution against coming in contact with the energized portion of the switch, and it is also preferable to take the strain of the line on a pole a few feet from the switch, rather than on the switch structure, particularly in the larger sizes. An insulating wood section in the control shaft separates the control handle from the remainder of the switch. Discharging horns can be fitted to this type of switch and when so equipped they have been found capable of breaking considerable loads.
Ques. How is the fuse arranged in the metal fuse break type of switch?
Ans. It is placed in a tube fitted with powdered carbonate of lime or some other insulating powder.
Fig. 2,215.—Pacific swivel type blade for Baum pole top switches. The twist type of blade, here shown, is especially adapted to switches operating in freezing or sleety weather. It will be seen that the first few degrees through which the rotating insulator is moved have the effect of twisting the blade between the shoes of the contact, which breaks any seal through freezing, or corrosion.
