Applicable to all line-commutated high-voltage direct current (HVDC) converter stations for the use of power exchange in utility systems. Presumes the use of 12-pulse thyristor converters, but can, also be used for 6-pulse thyristor converters (to be used with due care). Gives a set of procedures for the determination of the total losses of an HVDC converter station. These procedures covers all parts, and addresses no-load operation and operating losses together with their methods of calculation which use, when possible, measured parameters.