Electromagnetic noise spectrum at John TS [transmission station]

Canadian National (CN) is proposing the development of a commercial office tower on a site directly south of John Transmission Station (TS). CN is concerned about the potential effects of fields originating from John TS and other nearby sources on the operation of sensitive equipment and occupants of the building. Potential equipment and tenants might include data processing equipment and television and radio broadcasting companies. A study was conducted to characterize the severity of the electromagnetic environment at the site in order to address these concerns. Measurements of the electromagnetic spectrum from 100 kHz to 300 MHz were performed from a mobile test facility that features a 5 kW diesel generator and an extendible antenna mast. Peak measurements were made using a selectable measurement time of 0.05 s. It was found that the highest noise levels result from micro-gap discharges under dry weather conditions. The micro-gap discharges are characteristic of defect noise sources associated with substation hardware. At 0.5 MHz the noise levels are typical of median noise levels expected for the International Radio Consultive Committee (CCIR) defined business environment. At 74 MHz the noise levels are more severe than the expected levels for this type of environment. However, levels more representative of the business environment will be achieved by eliminating the micro-gap noise sources attributed to John TS. 6 refs., 11 figs., 2 tabs