Main tie main SWBDs fed from same utility transformers?

[housemoney]

2 utility transformers each with parallel feeds to the same switchboards.

I’ve worked on many MTM setups, can’t remember one where both sides were fed by the same normal source, seems like always fed from different transformers or utility feeds

Went so far as to ask the engineer if it was “as intended”, just informed “yes”.

What would the be the reason for this?

 

[ron]

Redundant transformers in case one fails or is taken down for maintenance

 

[housemoney]

Right, but

Redundant transformers in case one fails or is taken down for maintenance

That would be the benefit of a main-tie-main swbd fed from 2 separate transformers correct? These are fed by the same one, not seeing how that would allow for redundancy.

 

[jim dungar]

Right, but

That would be the benefit of a main-tie-main swbd fed from 2 separate transformers correct? These are fed by the same one, not seeing how that would allow for redundancy.

Depending on the location, like a large campus underground distribution, redundancy of the secondary conductors may be of more concern than the transformers.

Future planning may have also come into play. It is probably easier to add a second transformer than it is to reconfigure installed switchgear.

Don't forget the ability to maintain the main devices in the switchgear. The original designer may have thought that having two mains would allow one of them to be removed for an extended repair period while allowing the gear to remain on line.