Transactions . s conceded as a fact that the severity of damage done to trans-formers during short-circuit condition is in direct proportion to the amount H. W. YOUNG 021 of energy flowing into the circuit before the transformers are an automatic oil switch or fuse will clear the short circuit inthe least time can be answered as follows: High-tension automatic oilswitches of good design will open in approximately sec. under short-circuit conditions. High-tension fuses of good design will clear shortcircuits in approximately sec. or from ten to twelve times as ra
Transactions . s conceded as a fact that the severity of damage done to trans-formers during short-circuit condition is in direct proportion to the amount H. W. YOUNG 021 of energy flowing into the circuit before the transformers are an automatic oil switch or fuse will clear the short circuit inthe least time can be answered as follows: High-tension automatic oilswitches of good design will open in approximately sec. under short-circuit conditions. High-tension fuses of good design will clear shortcircuits in approximately sec. or from ten to twelve times as rapidlyas the automatic oil switches. Amount of Current Flow High-tension fuses will, under short-circuit conditions, permit acurrent flow many times the full load rating. Assuming that the currentflow with automatic oil switches will be no greater and by comparing thetime elements of the fuses ( sec.) and the time element of the auto-matic oil switches ( sec), it follows that the slower operating switch. Fig. 4.—Oscillogram record of 66,000-volt short circuit. Two in parallel. line 63,500 to 110,000 volts. will allow approximately twelve times more energy to flow into a shortcircuit than will flow with the faster operating high-tension fuse. Inconsidering the above values, it should be borne in mind that the amountof reactance in the circuit, including that of the transformers, will limitthe actual current flow with either device. The oscillogram record. Fig. 4, illustrates this point. This particulartest was made by connecting two 9000-kv-a. in parallel, short circuitingone phase to ground on a 63,500/110,000-volt star-connected total reactance approximated 20 per cent, and the current flow withthis 5 amp. fuse was 240 amperes. OVER-FUSTNG THE SUBSTATION The exceptionally rapid action of fuses will therefore permit overfusingthe transformers theoretically twelve times the normal current and stillsecure protection equal to that of an au
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
