Examples: In the first case, If there were a pair 10-kVA transformers, their capacity is 17.3kVA, and not 20kVA

30,000 VA total nameplate for three pots

0.5774 = 1/sqrt3

17,321 VA rating using only two 10kVA pots

In the second case, if there was one transformer removed from a three 10kVA pots, there capacity is reduced to 17.3kVA

20,000 total nameplate VA for two pots

0.8660 = sqrt3/2

17,321 VA actual capacity for two pots

In the third case, for two transformers serving a 20kVA load, the total nameplate capacity needed is 23.1kVA

20,000 VA load - served by two pots

1.1547 = 2/sqrt3

23,094 VA total nameplate transformer capacity for the two pots; id est, two 10kVA pots cannot adequately serve a 20kVA load.

Cooper Power bulletin R201-90-2 may be a useful reference.

[This message has been edited by Bjarney (edited 01-02-2003).]