Current transformer

A current transformer for measuring current flowing in a first bus conductor of a multi-phase electrical apparatus including multiple bus conductors, the current transformer comprising:

• a plurality of current transformer units combined into a bundle, each of said transformer units directly contacting another of said transformer units within said bundle and including
• an annular iron core for surrounding a first bus conductor through which an electrical current to be measured flows;
• and
• a secondary winding wound around said annular iron core for measuring the electrical current flowing through the first bus conductor;
• and
• a shield winding wound around an outside of said bundle of said current transformer units, wherein bus conductors of the multiple bus conductors, other than the first bus conductor, are disposed proximate the first bus conductor, and at least one of said current transformer units includes a first air gap, where no secondary winding and no shield winding are present, at a portion of said current transformer unit farthest from the bus conductors proximate the first bus conductor.