A solid insulated ring main unit (RMU) is a new type of power distribution equipment that integrates three technologies: external solid encapsulation, insulated busbars, and miniaturization of combined units. The switch and high-voltage live parts are integrally cast with epoxy resin, which serves as the insulation between live parts and the ground as well as between phases. This RMU does not emit any toxic substances, eliminating potential hazards such as gas leakage, explosion, and internal arcing. It features high insulation performance, high overall strength, and maintenance-free operation.
Depending on different configurations, it can achieve functions including interrupting load current, interrupting short-circuit current, manual and automatic switching of dual power supply incoming lines, current instantaneous trip protection, single-phase ground protection for small-current grounding systems, and communication.
Solid insulated RMUs are classified into three types: V units (circuit breaker units), C units (load switch units), and F units (combined electrical units). Each unit can be used independently or expanded freely. Its structure consists of an instrument compartment, an operating mechanism, and a primary part. The instrument compartment can be equipped with a microcomputer protection device (controller); the mechanism is a dedicated spring-operated mechanism; and the primary part adopts the APG (Automatic Pressure Gelation) process, which fully encapsulates the switch and arc-extinguishing chamber in epoxy resin and connects them to busbars via dedicated joints.
For the design of the arc-extinguishing chamber, the selected arc-extinguishing chamber uses special copper-chromium contact materials, R-type axial magnetic field contacts, and a complete one-time sealing and exhaust process. Compared with previous arc-extinguishing chambers (equipped with copper-aluminum contact materials, cup-shaped axial magnetic field contact structures, and incomplete one-time sealing and exhaust processes), this arc-extinguishing chamber has significantly improved performance in terms of short-circuit current interruption capacity, stability, electrical life, temperature rise, and insulation level.
This article is compiled and edited by DAYA Electric Group Co., Ltd. (//yardscreeksoaring.com/). Please indicate the source when reprinting.