Ok, so the following measurements were taken on two 408/208 transformers in a hospital. The tech in the field considered them to be overloaded, and therefore needing replacement (not by us, we're an inspection-only company). If the transformers were balanced, this would be clear-cut, but they're not, and so it isn't.
T1 (75 kVA):
H1:50.2 H2:47.5 H3:42.4 X1:97.8 X2:121 X3: 95.4 X0:48.9
T2 (112.5 kVA):
H1: 97.5 H2:62.4 H3: 65.7 X1:181.7 X2: 121.3 X3: 99.8 X0 81.7
Also, is there an easy (usable in the field) formula that I can give to the techs to determine whether a transformer is overloaded given nothing but the nameplate and a clamp-on ammeter? I've been looking for hours, and can't find one. All of the basic formulas assume balanced currents, and those are as rare as an honest politician in New Jersey.
Thanks for the help,
--Shannon
T1 (75 kVA):
H1:50.2 H2:47.5 H3:42.4 X1:97.8 X2:121 X3: 95.4 X0:48.9
T2 (112.5 kVA):
H1: 97.5 H2:62.4 H3: 65.7 X1:181.7 X2: 121.3 X3: 99.8 X0 81.7
Also, is there an easy (usable in the field) formula that I can give to the techs to determine whether a transformer is overloaded given nothing but the nameplate and a clamp-on ammeter? I've been looking for hours, and can't find one. All of the basic formulas assume balanced currents, and those are as rare as an honest politician in New Jersey.
Thanks for the help,
--Shannon