OCR Text |
Show Dynamos. There exists a general and deeply root ed idea that direct current dynamos of very high potential are not at all prac tical. The actual historical and practical prac-tical facts are that the high potential direct di-rect current machines were more exten sively and successfully operated when the dynamo first came into general uso about 1880 than any other type, either direct or alternate. Furthermore, their number and size have largely increased, and the voltage at which they can b I practically worked has been steadily i raised until we now have 60 light dyna- i mos as the standard size of large ma- ! chines, generating about 3,000 volts and 10 amperes. Arc dynamos of 90 light capacity are also regularly made by several manufacturers, manu-facturers, and 120 or even 125 light ma-chines ma-chines are built and used. I happen to know of one station where there are four j arc dynamos rated at 125 lights each ! which run every night with a load of j from 100 to 105 lights. These machines must generate about 5,000 volts each. No great practical or other difficulty is found in operating arc machines, except that of danger to persons, but this is merely due to the high potential and does not depend very much upon the type of machine or character of current. Cas-sier's Cas-sier's Magazine. |