Patent ID: 6617839
Filing Date: 2003-09-09
Classification: H02H

Abstract:
A method for determining saturation of a current transformer comprising the steps of:deciding a decision function which utilizes a secondary current value of the current transformer, wherein the decision function is preferably one of a second-order difference, an adjusted second-order difference, an energy function of the second-order difference and an energy function of the adjusted second-order difference; deciding the decision function value at each point of time by measuring the secondary current value at predetermined time intervals; determining whether the decision function value is greater than a threshold value at each point of time; and when the decision function value is determined to be greater than the predetermined threshold value, determining the beginning or end of the saturation, wherein the saturation of the current transformer is determined to end if the saturation of the current transformer begins before the point that the decision function value is greater than the predetermined threshold value, and the saturation of the current transformer is determined to begin, if the current transformer saturation ends or does not begin before the point where the decision function value is greater than the predetermined threshold value.