JPS5724864A - Phase difference detector - Google Patents

Abstract

PURPOSE:To achieve a compact detection of phase difference at a low cost by connecting conductors of different circuits in the polarities opposite to each other in forming a primary winding of one unit AC machine. CONSTITUTION:Conductors are connected in the polarities opposite to each other in the primary winding of a current transformer 4. When the current values and phases are both equal in the currents I2 and I3 flowing through load motors 2 and 3, the magnetomotive forces generated in the core of the current transformer 4 cancel each other. Thus, no current develops in the secondary winding thereof. When there is a difference in either or both of the current values and the phases, current flows through the secondary winding and thus, voltage develops across the resistances 6. Therefore, when the motors 2 and 3 have such a constant current characteristic as to change the phase difference along, the circuit acts as a phase difference detector circuit. This reduces current transformers to one unit eliminating the need for aligning current ratio thereby enabling a compact detection of phase difference at a low cost.