Symmetrical-component analysis applied to phase convertors of the Ferraris¿Arno type

The paper provides a theoretical explanation, in symmetrical-component terms, of the N-machine capacitor-Ferraris-Arno phase-convertor in a manner which clearly shows the purpose of the so-called pilot motor and includes the single-phase motor as a special case. It is shown that a perfectly balanced 3-phase output can be obtained, but that the ideal conditions required are not likely to be encountered in practice. A theoretical expression for minimum unbalance is established and verified by practical tests using bridge networks for the direct measurement of sequence-component quantities.