Pollution of the radio spectrum from the generation of impulsive noise by high voltage equipment

Impulsive noise is generated by high-voltage plant experiencing complete or partial breakdown. The spectrum of the impulse depends on the dielectric involved in the breakdown: oil and SF6 produce frequency components up to 1 GHz, whereas radiation due to air discharges is restricted to below 200 MHz. The radiation efficiency of the connecting metallic structure to the discharge must also be considered. Digital recordings of impulses emitted during several insulation defects and switchgear operations are presented. The waveforms were captured using a 1 GHz recording system. The spectra and impulse emission pattern are also presented. (5 pages)