Guys,If you are using a modern high input impedance DVM for your measurements, you might try loading the winding you are measuring with something between 1K and 10K ohms, and see if your measurements make more sense. A couple of years back, I was trying to figure out the windings of a band saw blade welder transformer with a Fluke industrial DVM. It should have been a real simple job, but I wasted an entire day getting readings that were all over the place, unrepeatable, and totally inconsistent with the way I "knew" the transformer had to work. After I loaded the winding under test with a 1K power resistor, all the measurements made sense and were much more consistent. Might be an issue with these NST measurements as well.
Dave mddeming@xxxxxxx wrote:
Hi Gary, Bart, All, ? Back in Oct '07 I measured the Vin/Vout ratio forward and backward on a 15/30 Transco NST using an old Triplett 630-Aanalog meter, which has a 6KVAC scale. The forward ratio was 124:1 at 48.4 Vin implying 14880 Vout at 120 Vin, but the reverse ratio was only 37:1 with 120 Vin on the secondary. These results are very inconsistant.?I will have to rerun it when I get a chance, but it seems to indicate that the reverse method doesn't work well for an NST ? Matt D.
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