What are the advantages of ring main units over conventional switchgear?

Ring main unit (RMU) is a sealed switchgear unit, used in the secondary power distribution system, and sealed with vacuum or SF6 gas. It can protect the secondary transformer from transients on the load or power supply side. Because it is composed of CB and isolator, it can achieve the purpose and seal the system, thereby reducing maintenance costs. It has another advantageous function in which the pressure of the container gas (mainly SF6) increases as the voltage in the container increases.