IN FROZEN CENTRAL

Evening Star, Issue 19633, 12 August 1927, Page 2

IN FROZEN CENTRAL

THAWING HATED IH PIPES HIE THESE AIIV APPLIANCES? Frozen water in pipes is one of the misfortunes of those who Jive in Otago 'Central during the winter. Jn the Central, though, there is a plentiful supply of electricity, anil there must he some appliance ou the market which will thaw tho pipes, Jn a magazinc published in 1900, “Hydro” unearthed an article on a transformer for thawing frozen water in pipes, and it is republished with tho hope of some electrical firm supplying information of appliances which they know mo on the market.

“A thawing transformer, recently placed on tho market by tho Pittsburg Transformer Company, Duisburg, i'a., is equipped with primary Juso tucks, a controlling device for adjusting the current, a heat indicator, and a large capacity secondary switch. The primary leads of the transformer run through porcelain bushings in the backboard .and into tho fuse blocks. Within tho transformer is a porcelain terminal block, changing tho connection of which adapts the transformer to operation ou circuits of approximately 1,100 volts or circuits of approximately 2,200 volts. “ Four secondary leads issue from the front of the case and pass to the terminals of tho double-polo • doublethrow switch. Throwing this switch to the loft connects the secondary coils in multiple, so that the transformer delivers 371 volts and has a capacity of about 800 amperes. Throwing switch to the right puts tho secondary coils in scries, so that a pressure of seventyfive volts is obtained, the current capacity being 100 amperes. “The secondary lino passes through the choke coil, and from there to the heat indicator. The choke coil consists of several turns of copper rod, and has a laminated iron core, supplied with a handle for pushing in and out, thus altering the choking ellect to suit tho conditions involved. “The heat indicator is simply a short section of lead pipe connected in scries with the Jowrvoltago winding, in the samp manner as a, fuse, its temperature being a guide as to the heating of tho pipe under treatment. “Tho capacity of tho thawer is normally 100 or 800 amperes, as stated above, but currents considerably in oxi cess of these values may be drawn for short periods. It should bo remembered that usually tho temperature of the air will bo below freezing point or even many degrees below zero, lender such conditions a temperature rise in the .transformer as high as 100 to 125 degrees C. above the air will .still be within tho usual working limits. “Tho intermittent nature of the work’is also favorable, and it will frequently he found that <SOO to GOO or 1,000 to 1,300 amperes can safely bo drawn from tho thawer. Snow or ice can also, be applied to the cast-iron ,c|»so to assist in cooling when running under extreme loads for considerable periods of time. “While pipes exposed to the air generally hurst in freezing, yet it has been found that when they are in the ground very few eases of bursting are met with. It has been observed that but one case in GOO shows rupture under such conditions, due perhaps to tho fact that the earth first freezes solidly around the pipe, thus preventing its expansion from internal pressure! This is of the greatest importance. for were it otherwise, electrical thawing would be ot small practical use.

'• It is to he nol-cd that ammeters or voltmeters arc valueless for this work, and are therefore a needless expense. The operator has no interest in flip voltage or tho current strength, as long as these arc sufficient for the purpose. The heating effect is the important feature, and it is a simple malter to judge this by touching Ihe heat indicator with the hand or with a wet mitten. The most unskilled operator knows when this pipe is hot. althouga he might he entirely at a loss to know whether he should use 2(10 amperes or 500 amperes were he, dependent upon an ammeter, it is claimed that Os simplicity makes this outfit I lie most practical as well a« the cheapest successful device of this kind yet produced.”