Characterization of electromagnetic noise at very high frequencies in Hydro-Quebec's 735 kV substations

Tests were conducted at a Hydro-Quebec 735 kV substation to characterize the electrical parameters of intrusive noise found at high frequencies (between 20 to 1000 MHz). A first series of measurements were made in 1991 and 1992 to determine the overall reliability of the remote digital protection system. Subsequent measurements were made in 1995 for a period of 7-1/2 months. Hundreds of records of intrusive noise were made. Circuit breaker opening and closing tests were repeatedly performed. Results showed that the intensity of the high-frequency intrusive electric fields in the substations was significantly greater than expected. These results will evidently impact on the specifications of immunity criteria and also on the future testing of telecommunications equipment. The frequency band and the severity levels required during standard tests were verified. 1 ref., 5 figs