4-Position Load break Switch for Pad- Mounted Transformer Loop Feed

[faresos]

Hello Everyone,

I'm reviewing a spec for this transformer and it appears there are option for the configuration of the switch will let it to operate and allow for A & B sides to be paralleled and connected to the transformer. The current design calls out this transformer will receive two power sources from two separate buses upstream. The confusing part, this seems to be similar to closed transition concept which we need to avoid due to a lot of issues we will have to deal with. What is exactly the intent of this configuration and where it can be used. Our intent is only to have a manual selection between the two sources at the transformer primary section.

Thank you!

 

[ron]

Although most 4 position LBOR switches are used for closed transition, it can be connected to be open transition. See some wiring schematics on Page 7 from the pdf linked below. See where is says break before make

https://www.eaton.com/content/dam/eaton/products/medium-voltage-power-distribution-control-systems/line-installation-and-protective-equipment/four-position-sectionalizing-loadbreak-switches-catalog-ca800005en.pdf

 

[faresos]

Thanks, Ron! My concern is still having the two sources connected together to a common bus after the switching. I have reached out to a vendor and they have suggested to use 3-position switch (I didn't know this configuration exist), which doesn't allow to parallel sources to the transformer: (Line A Only, Line B Only, Off) which used on dual source applications.

 

[jim dungar]

Sometimes the A-B connection is used for looping the primary cable, it selects 'direction A or B or lets the loop continue rather than paralleling sources.