In This Issue 2000 in Review by Simon Fortin, SES Users' Group Meeting by Bruno Simon, SES Using HIFREQ for Analyzing Control Cable Transients by S. G. Lodwig, ComEd CDEGS Tips by SES employees CDEGS New Features by Simon Fortin and Aditya Choubey, SES Latest Technical Papers by SES by SES employees SES' New Web Site by Bruno Simon, SES

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HIFREQ and FFT are used to analyze different transient voltages on control cables in substations. In ComEd, PLC’s and microprocessor relays are located in shielded control buildings inside the HV substations and are subjected to electrical noise created in a substation yard during high voltage air disconnect switching. The source of the noise was from adding surge capacitors on SF6 138 kV circuit breakers. A back to back switching circuit was created that coupled noise to control equipment wiring and led to equipment damage.

HIFREQ and FFT studies were undertaken to analyze the spectrum of the noise and to compare predicted and measured transients. An important feature of the studies was the precise location of the natural frequencies of the switching circuit. Not only the voltage and current magnitudes are valuable, but the resonant frequency will also be a good indicator of the accuracy of the models using CDEGS.

Two ComEd authors are presenting a paper at the EMC Conference in August, 2001 describing the problem in detail. This paper will be published in its entirety in the 2001 Annual Users' Group Meeting handbook.

S. G. Lodwig, ComEd