| 摘要 |
An instrument (1) and a method for detecting partial electric discharges involve acquiring a discharge signal (10), for example picked up by a direct-measuring impedance device (7) through a broadband HF acquisition channel (18), and acquiring the discharge signal (10) in a narrowband LF acquisition channel (180) complying with regulations, using on the LF acquisition channel (180) a trigger controlled in slave mode by a trigger of the broadband HF acquisition channel (18); they also involve acquiring another discharge signal (32) picked up by an indirect-measuring impedance device (8) through a second narrowband LF acquisition channel (180A) and comparing digital signals (34, 34A) generated in the first and second LF acquisition channels (180, 180A), in order to generate a balanced digital signal (36) without components representative of common mode electrical signals present in the measuring circuit. |
| 主权项 |
1. An instrument (1) for detecting partial electric discharges in an electric apparatus (2), comprising:
an HF input stage (9) designed to receive an analogue signal (10) representative of electrical pulses correlated with the partial discharges and to output an HF digital signal (11) forming an uninterrupted sample flow representative of the full waveform of the pulses, said input stage (9) forming a detection bandwidth of at least 20 MHz; a trigger module (14) connected to the HF input stage (9) for receiving the HF digital signal (11) and configured to generate a control signal (15) designed to allow selection of a plurality of samples of the flow according to a predetermined criterion; an acquisition unit (16) connected to the HF input stage (9) for receiving the HF digital signal (11), and to the trigger module (14) for receiving the control signal (15), and configured to select from said sample flow groups of samples forming segments corresponding to individual electrical pulses as a function of the control signal (15); an output stage (17) designed to receive the data received from the HF acquisition unit (16) to allow processing thereof in order to derive values of at least one predetermined parameter, wherein it comprises: an LF input stage (19) designed to receive the analogue signal (10) and to output an LF digital signal (20) forming an uninterrupted sample flow representative of the waveform of the pulses, said LF input stage (19) forming a detection bandwidth of less than 500 kHz; a compensation module (25) coupled to the LF input stage (19) to dynamically slow down the uninterrupted flow of LF digital signal (20) samples, thereby making available a compensated LF digital signal (26); an LF acquisition unit (27) designed to receive the compensated LF digital signal (26), connected to a trigger module (14) for receiving the control signal (15) configured to select from the compensated LF digital signal segments corresponding to the segments selected by the HF acquisition unit (16), that is to say, relating to the same corresponding electrical pulses, the output stage (17) being designed to also receive the data received from the LF acquisition unit in order to be able to derive, for each pulse, an amplitude parameter value relating to the amplitude of that pulse, correlated with a corresponding predetermined value of that parameter. |
