Surge arresters provides lightning protection for transmission and distribution systems. It is a protective device designed primarily for connection between a conductor of an electrical system and ground to limit the magnitude of transient over voltages on equipment. This is also called as arrester; lightning arrester. This is really a voltage-surge arrester. A typical surge arrester consists of disks of zinc oxide material sized in cross-sectional area to provide desired energy discharge capability and in axial length proportional to the voltage capability. These disks are then placed in porcelain enclosures to provide physical support and heat removal and then sealed for isolation from contamination in the electrical environment. This is also used at bonding points of the capable system. They are referred to as sheath voltage limiter arresters. Those using metal oxide nonlinear resistors are used extensively in HVDC schemes for voltage protection. These are also applied within AC harmonic filters.