This chapter provides guidance on the procedures for insulation co-ordination of high-voltage direct current (HVDC) converter stations. Also, chapter discusses the fundamentals, including classifications of various overvoltages and present practices of surge arrester selections in HVDC converter configurations. This chapter outlines the applications of metal oxide arresters without gaps and their basic characteristics for HVDC converter stations. Typical HVDC arrester protective scheme and determination of stresses of an arrester considering the configuration of HVDC are also presented. Chapter also covers protection strategy for overvoltage protection, concept of multi-columns arrester and coordination of different arresters depending on the location. The chapter describes insulation coordination requirements and practices for both line commutated converter (LCC) and voltage Sourced Converter (VSC) stations.