Current Transformation Ratio

Author: E.E. Kimberly

In a transformer of 1:1 ratio, 1 load ampere flows in the primary for every load ampere in the secondary because the corrective or cancellation ampere-turns added in the primary must be equal to the demagnetizing ampere-turns N₂I₂. The current-carrying capacity, and hence the size of wire, in the primary winding should be the same* as that in the secondary winding. The exciting current is so small as to be negligible and has been ignored in the foregoing statement. The weight of wire in the secondary should be the same as that in the primary because the volt-amperes are the same in each. If the number of secondary turns be only one-tenth as great as the number of primary turns, the current-carrying capacity of the secondary conductors should be 10 times as great as that of the primary turns. For every 10 load amperes in the secondary, 1 load ampere will flow in the primary. Thus, the current transformation ratio of a transformer that is normally designed is inversely proportional to the turns ratio. The transformation is accomplished with but small power loss in the transformer.