Applies to all line-commutated high-voltage direct current (HVDC) converter stations used for power exchange in utility systems. Presumes the use of 12-pulse thyristor converters but can also be used for 6-pulse thyristor converters. Presents procedures for determining the total losses of an HVDC converter station. Cover all parts, except synchronous compensators or static var compensators and address no-load operation and operating losses together with their methods of calculation which use, wherever possible, measured parameters. The contents of the corrigendum of October 1999 have been included in this copy.