INSTRUMENT AND A METHOD FOR DETECTING PARTIAL ELECTRICAL DISCHARGES OCCURRING IN AN ELECTRIC APPARATUS

摘要

An instrument (1) for detecting partial electric discharges occurring in an electric apparatus comprises an input stage (6) adapted to receive an analogue signal representative of an impulse correlated to a partial discharge and to generate at the output a digital signal (5) representative of the entire wave form of said impulse, said input step (6) defining a detection band width of at least 2 MHz, an output stage (7) connected to the input stage (6) to receive said digital signal (5) and adapted to transfer data in digital form at the output from the instrument (1), and a processing stage (8) connected both to the input stage (6) and to the output stage (7) to receive said digital signal (5) and to transfer to the output stage a filtered digital signal (9) equivalent to the digital representation of said analogue signal that would be generated by said input stage if the imput stage had a predetermined detection bandwidth with a value smaller than 500 kHz. Prior art instruments do not allow to detect impulses in such a way as to be able to preserve the wave form information useful for subsequent diagnostic assessments and, simultaneously, to attribute to the signals a value of amplitude in compliance with the standard requirements.