Transformer Question

[Woodwalker128]

Does anyone know why there are two plus signs behind the 15KVA on this transformer? The best I can tell is that it designates additive polarity. However, that doesn't explain two plus signs.

61646165

[reppy007]

Does anyone know why there are two plus signs behind the 15KVA on this transformer? The best I can tell is that it designates additive polarity. However, that doesn't explain two plus signs.

61646165

I cant recall seeing those pluses on any transformer,maybe 1 but never two.

[US & CA Tramp]

It is an old REA transformer. The + usually meant how many bumps up on the tap. - was bump down.