When the ratio is low it becomes difficult to obtain good results with the single primary turn. For that purpose wound primary CT’s are used where both primary and secondary turns are wound on the torroidal core. The ranges available are from 5/5A to 100/5A. Also Secondary 1A can be provided. Optional mounting arrangements are provided as the CT is mounted between two Bakelite plates and brass terminals are provided for connections of primary & secondary.

The standards define a voltage transformer as one in which “the secondary voltage is substantially proportional to the primary voltage and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections.”

This, in essence, means that the voltage transformer has to be as close as possible to the “ideal” transformer. In an “ideal” transformer, the secondary voltage vector is exactly opposite and equal to the primary voltage vector, when multiplied by the turns ratio.