GB/T 311.12-2025 Active

This document provides guidelines for insulation coordination of high-voltage direct current (HVDC) converter stations using line-commutated converters (LCCs). The purpose is to evaluate the overvoltage stress of converter station equipment under DC voltage, power-frequency voltage, harmonic voltage, and impulse voltage, and to determine the rated withstand voltage level of the equipment. This document is only applicable to insulation coordination of LCC HVDC converter stations protected against overvoltage by gapless metal-oxide arresters. It also introduces methods for determining the protection level of arresters in series or parallel combinations, and provides typical arrester configurations and arresters' stress levels. An example of insulation coordination for an LCC HVDC converter station is provided in the appendix to support the content and basic analysis techniques described in the main body of this document.