The development of the current power system focuses on the usage of ecological resources. Low power loss, low maintenance spending, reliable performance, flexible configuration are required on the medium voltage switchgear. Due to its features such as long service life, compact size, and recycling, MPL ERM ring main units have proved successful in terms of economy and ecology. It appears more important for underground cabled power distribution network in improving its devices and other aspects, with the rapid development of urbanization; ring main units (RMU), as the major device for protection and segment isolation to ground cabled distribution network, are widely used in urban power grids, due to its safe and reliable performance, compact and superior cost-effectiveness. Megawatt Power Limited as the leader in the field of distribution switchgear has been designing and manufacturing high-quality power distribution switchgear since 2012, with countless switchgear operating reliably over the country till now. Based on the design concept of full insulation and fully sealed, all primary parts within ERM RMU are fully sealed inside the stainless-steel main enclosure, protect too against condensation and external contaminated environment; the protection degree of the main tank body is up to IP67. Its modular unit, anti-corrosion enclosure, and perfect tightness make them suitable for applications in various places.