400a extensible type sf6 circuit breaker ring main unit

A very specific and technical question!

The "400A extensible type SF6 circuit breaker ring main unit" is a type of electrical equipment used in power distribution systems. Here's a breakdown of what each part means:

In summary, the "400A extensible type SF6 circuit breaker ring main unit" is a high-voltage electrical circuit breaker that is designed to be extensible, uses SF6 as an insulating medium, and is part of a ring main distribution system with a current rating of 400 amperes.