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Old 07-15-2002, 12:22 AM
Steve Stadelman Steve Stadelman is offline
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Location: Portland oregon area
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Hi Bryan, you are very well set indeed. However you need to check if your transformers will go down to 60 volts. I am assuming that these are the type (like mine) that take 480 down to 240 and 120 depending whether the two secondaries are wired in series or paralell. If you only lower your 240 to 120 you will only have an amperage doubling. Since you are talking about using 65 amp scrs you will only achieve 130 amps. Six millimeter hot section molys can use about 170-180 amps. So in this configuration you will not be using the elements fully and the furnace will be sluggish. If both transformers can be configured to 240 down to sixty volts each scr can be wired to a 60 amp breaker and will draw from 40-45 amps depending on where you set the limeters. If you use elements with 28" hot zones and 16" terminals they have a hot resistance of about .179 ohms and at 166 amps at 2375f take about 30 volts to push the current. Two of these in series will produce just shy of 10kw. Two circuits like this is equal to what Kyle Gribskiv is using to melt using one of Petes 325 pounders. Pete and I will not use two small scrs but one large one and a larger transformer then the power comes from the secondaries in two parallel circuits. Kyle recently lost an element in one circuit and the furnace just limped along on half power. So your redundant power idea is really attractive. Steve.
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