Cleaning Insulators by High-pressure Jet
Page 41
If you've noticed an error in this article please click here to report it so we can fix it.
A MOBILE unit based on an Autocar chassis has been r-k introduced by the Los Angeles water and power department for cleaning the insulators of overhead electric power-supply poles. The vehicle carries a 900-gallon water tank, a 72-ft. extensible ladder, a pump driven by a power take-off and a high-pressure hose line. An operator seated at the top of the ladder directs a jet of water of up to 1,000 lb. per sq. in. pressure at the insulators. Two such vehicles deal with 18,500 poles once every three months.
Besides halving the cost of cleaning insulators, the need
for providing duplicate supply lines has been diminished. Old cleaning methods by hand required that current be switched off, but spraying does not interfere with the supply. The Los Angeles water is such that it may be used without treatment to increase its resistance. It is stated that water with a resistance of higher than 1,000 ohms per c.c. may safely be used.
Seven men form the crew of a unit. One man sits on the ladder operating the spray, another operates warning lights for the benefit of passing traffic. These two, and the driver and the ladder operator, change jobs every two hours. Another man operates a spotlight, a sixth is designated a line patrolman, whilst a' seventh is the foreman.
The high-pressure spray method of cleaning insulators was first investigated 22 years ago. The department built a tower wagon with the necessary hose equipment fitted to the platform. A second appliance was constructed in 1939 with an extensible ladder to provide greater versatility than a simple tower. The latest unit was built last year to the department's specification by the Yankee Motor Bodies Corporation, Los Angeles The Autocar chassis has a 16-ft. 8-in, wheelbase and the engine is placed beneath the floor of the cab. The hydraulically operated ladder was made by the Seagraves Corporation is lightweight steel alloy and has copper-lined wearing strips.