Is there a standard scheme for power transformer wire colors?
Primary leads ————– black (if tapped) Common —————– black Tap ——————– black/yellow End ——————– black/red High voltage secondary —– red Center tap ————- red/yellow Rectifier filament winding – yellow Center tap ————- yellow/blue Filament winding No. 1 —– green Center tap ————- green/yellow Filament winding No. 2 —– brown Center tap ————- brown/yellow Filament winding No. 3 —– slate Center tap ————- slate/yellow I have seen primaries with other color schemes; if it includes black it should be a primary lead of some sort. I’ve seen transformers with only one filament winding that was brown. I’ve seen high voltage secondaries with red/white centers. And on old transformers, the colors may have faded to the point brown looks black or green looks black or brown, and so forth. I’m not aware of any standard for filament winding numbering, so if there is more than one, verify the voltages. The rect
