Each secondary winding (of which there may be many) on a transformer has a voltage associated with it, along with a maximum current or power which it can deliver to a load. The total VA rating of all the windings will normally equal the VA rating specified as the Total Load Rating of Transformer.
The secondary voltages for each set of secondary windings must be specified, along with the current or VA in each case. The only exception to this rule is when there is only one secondary winding, in which case it will have a rating equal to the total load rating for the transformer.
The voltages should be specified as either a single number in box 1 of each row, where the winding is not multi-tapped, or as a string of numbers of the form 0-12-15-18 V, or 24-0-24 V. For centre-tapped windings the form 110 V C.T. or 110 V C.T.E. for a centre-tapped earth are acceptable.
The loading of each winding on a multiple wound transformer should be specified in box 2 of this row next to its corresponding voltage, and its units, mA, A, VA, kVA selected in box 3 of each row.
In the case of multiple windings it is possible for the sum of the individual loads to exceed the total load rating of the transformer. In this case it must be realised that the actual load applied to the unit should not exceed the total VA rating.