Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


RMU and switchgear

RMU and switchgear

RMU and switchgear

Hello friends,

could someone please explain the main difference between a ring main unit and MV switchgear. in a substation do we have to have the two?

RE: RMU and switchgear

Switchgear is a fairly generic term for equipment which incorporates switches or circuit breakers.

An RMU is a specific type of switchgear comprising a pair of switches for a ring circuit to loop in and out, plus a switch-fuse or breaker for the tap-off feeding the load, all integrated into a single unit.

RE: RMU and switchgear

In MV switchgear, you can have incomings and outgoings as per load. But in RMU it is mainly two incomings+1 outgoing so that your outgoing power is not disturbed.


RE: RMU and switchgear

But, RMUs with multiple feeders are also available in the market. This is a variation of the basic RMU.

RMUs are mostly suitable for outdoor installation with minimum protection and controls. In some cases even the external control supply also not use.

RE: RMU and switchgear

Agree with Krisys.
Maybe you can check ABB Safeplus for more details.


RE: RMU and switchgear

I am currently using Schneider 12kV RMU's in Minisubs (630A Isolator/200A Breaker/200A Breaker) and as a Main 11kV Switchboard 20kA we find its a cheaper option than the withdrawable
type. One can add features such as standoff trip/close facility. The VIP410E protection relay has adequate settings.

RE: RMU and switchgear

For the Schneider Make RMUs, you don't need a separate control power supply. It uses the self powered release mechanism. This is a specific advantage, when it comes to the remote area, where providing a dedicated control power supply is a problem.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close