DC switchgear is the key device in the DC transmission system convert station and is applied to the commutation of various operate manner

clearance of the fault

maintenance and disconnect in the DC transmission system

which influences the reliability

availability and maintainability of the transmission system.According to the relative GB standards

technical guidelines and rules as theoretical support

on the basis of the specific requirement of various operate manner and control strategy in the DC transmission system for DC switchgear structure.The purpose and the class is discussed include DC transfer switches

disconnectors

earthing switches and by-pass switches.The analysis and contrast is carried out for DC switchgear based on the basic principle

structure type and characteristic.The technical difficulties and development trends of DC switchgear are put forward.This study provides a reference for the relative researchers and project designers.