COMTRADE, which is an acronym for Common Format for Transient Data Exchange, is a file format specified in IEEE® Std C37.111 for storing oscillography and status data related to transient power system disturbances. COMTRADE is maintained by the IEEE Relay Communications Subcommittee of the IEEE Power System Relay Committee (PSRC). For more information, visit the IEEE Power System Relay Committee web site.

PQDiffractor is a free COMTRADE viewer written by Electrotek Concepts for viewing and diagnosing COMTRADE files, and is a free software download from

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