DEVICE FOR THE DETECTION OF CORONA DISCHARGES IN ALTERNATING CURRENT OVERHEAD LINES

摘要

The control device comprises an antenna (10) for receiving an electro-magnetic radiation emitted by an electric alternating current overhead line. The antenna is connected to an amplifier (20) of which the output (22) is connected to an oscilloscope (30) so that the output signals from the amplifier (20) as well as the vertical and horizontal deviation of the spot act on the image given by the oscilloscope (30). The amplifier (20) provides for the amplification of a wide frequency band going from a frequency lower than that of the network to at least 20 kHz. However, the amplification of the band lower than 10 kHz approximatively is reduced. The spectrum of the frequencies of the output signals from the amplifier (20) is supplied to the oscilloscope (30). When controlling an electric overhead line, the low frequency signal of the network alternating voltage appears on the screen of the oscilloscope (30) as a regular closed curve. On the other hand, in the case of a corona discharge at faulty points of the electric overhead line, the generated high frequency signals appear like deformations of the regular closed curve. The type of the deformations, their position on the closed curve and their amplitude enable to determine the nature and the location of the faults.