Patent ID: 9606169
Date: 2017-03-28
CPC Classifications: G01R,H02H

Claim:
1. A method of verifying a protection apparatus, the method comprising: applying a test current to an alternating current (AC) bus to identify a line connection state of an inner circuit of the protection apparatus, the AC bus configured to connect an input terminal of a double tune filter to an input terminal of a high pass filter and transmit AC power supplied from an AC power source to the double tune filter and the high pass filter; identifying that there is no misconnection in the inner circuit when all the output currents of the double tuned filter and the high pass filter are zero with respect to the applied test current; setting a plurality of relay elements for sensing an abnormal state of the protection apparatus when there is no misconnection; receiving an input related to test information for testing each of the plurality of relay elements, the input related to test information including a micro current that is input to the double tuned filter; comparing a level of the micro current input to the double tuned filter with a level of a current output from the double tuned filter; and identifying that an abnormal state is generated when a difference between the micro current input to the double tuned filter and the level of the current output from the double tuned filter exceeds a preset value, wherein the plurality of relay elements comprise an overcurrent relay element, a ground overcurrent relay element, an unbalanced current relay element and a percentage differential relay element.