Patent ID: 9018962
Filing Date: 2015-04-28
Classification: G01R,H02H

Abstract:
1. A system for protecting a transformer having: (a) an input winding, (b) at least one output winding intended to be coupled to a load, and (c) having a neutral line returned to ground, and wherein when the transformer is subjected to electro-magnetic conditions excessive currents can flow in the neutral line and cause the core of the transformer to saturate, the protective system including: (a) circuitry for sensing the level of the current flowing in the neutral line, hereafter referred to as “I (b) circuitry for sensing selected even and odd harmonics of the current flowing in the output winding coupled to the load and processing the selected harmonics to determine whether predetermined relationships pertaining to the harmonics indicative of core saturation are present for a preselected time duration and producing a harmonics status signal corresponding thereto; and (c) circuitry responsive to the first signal alarm and to the harmonic status signal for producing a second alarm signal.