This Technical Specification is intended to provide an overall and consistent set of guidelines to facilitate the specification of equipment for the DC side of a high-voltage direct-current (HVDC) system using Line-Commutated Converters. For end-to-end HVDC transmission systems, the Technical Specification covers all DC-side equipment located between the converter valves and the DC overhead line or cable termination, excluding the converter valves themselves. For back-to-back HVDC systems the Technical Specification covers all DC side equipment excluding the converter valves themselves.