GB982700A - Improvements in or relating to apparatus for the detection of discharges in high-power transmission channels - Google Patents

Abstract

982,700. Fault testing. MARCONI CO. Ltd. July 11, 1963 [Aug. 28, 1962], No. 32979/62. Heading G1U. Apparatus for detecting corona and arcing discharges in a high power high frequency transmission line or waveguide comprises means for tapping energy from the line or waveguide, means for rejecting from the energy tapped off energy within the frequency band which the line or waveguide is designed to transmit, and means responsive to energy outside the band for indicating the occurence of discharging or arcing. In Fig. 1 energy is tapped off a waveguide by a connection 2, which is shown as a loop but is preferably a coupling hole, and passed through a filter 3 to a noise detector 4 and indicator 5. The filter 3 is preferably a length of waveguide having its lower cut-off frequency above the frequency of propagation in waveguide 1. In operation any discharge in the waveguide will produce noise signals over a wide frequency band which will be detected by the apparatus 5 and may be used to switch off the energy propagated in the waveguide. In a modification, Fig. 2 (not shown) a filter tuned to pass energy at a harmonic of the frequency of the energy in the waveguide is included between the filter 3 and detector 4. In a further modification, Fig. 3 (not shown), the output of filter 3 is fed in parallel to three filters tuned respectively to the frequencies at which peak noise signals may occur in three sections of a waveguide channel, the frequencies being different due to different dimensions, different obstacles &c. and in this way the faulty section of waveguide can be located. In another arrangement, Fig. 4 (not shown), applied to a coaxial line, the output of noise detector is supplied to a frequency spectrum analyser; this again gives an indication of the location of the fault.