Patent ID: 7724152

Claim:
A tap change operation monitoring apparatus for an on-load tap changer, said tap change operation monitoring apparatus comprising: torque sensing means for detecting drive shaft torque exerted on a drive shaft of an operating mechanism for operating said on-load tap changer which is provided with a diverter switch, a tap selector and a changeover selector; operating mode discrimination means for discriminating operating mode in which said on-load tap changer performs tap change operation; torque waveform data recording means for recording torque waveform data concerning said drive shaft torque detected by said torque sensing means for each operating mode discriminated by said operating mode discrimination means; reference data setup means for setting monitoring target specification data for each operating mode of said on-load tap changer and then setting and storing a reference value of said monitoring target specification data and a management value of a permissible variable range thereof; waveform processing means including: a noise filtering circuit for extracting the torque waveform data recorded in said torque waveform data recording means and generating processed torque waveform data from which noise components have been removed by removing frequency components exceeding a specific first frequency from the extracted torque waveform data; a waveform shaping circuit for generating shaped torque waveform data by removing frequency components exceeding a specific second frequency which is lower than said first frequency and set within a range in which a torque change caused by the tap change operation of said diverter switch remains in a torque waveform after shaping; and reference operating time extraction means for extracting time of occurrence of an extremum of a waveform obtained by differentiating said shaped torque waveform data in the time domain within a specific time period as reference operating time; specification data extraction means for extracting data corresponding to said monitoring target specification data as specification data from the reference operating time extracted by said waveform processing means and said processed torque waveform data; and anomaly judgment means for comparing the specification data extracted by said specification data extraction means with the reference value set by said reference data setup means and judging that an anomaly has occurred if the result of comparison exceeds the management value of said permissible variable range.