Two DNO 11Kv/400/230v transformers on different HV lines originally supplied two separate buildings on an industrial site. The two separate buildings are now one large steel framed one. So we have two DNO intakes and no clear demarcation within the installation. I remember reading somewhere about issues arising in such situations but cannot find the article. I am keen to establish if any issues are serious enough to seek alternatives. One of the intakes has a Biomass plant feed-in with g59 relay. Both intakes are circa 1MVA.
Having two seperate HV supplies in the building requires that you have a full understanding of the LV distribution through the building. It also requires that you have the installation set up in such a way that the LV is completely identified and can not be mistaken or otherwise altered or interchanged. If not properly segregated you could in theory end up accidentally backfeeding the other electrical system.
The neutral earth connections are also of concern as you can have circulation currents in there that could suprise the unwary. In an emergency would you be able to identify quickly where the power source was sourced from and how to isolate ? you can have currents in the neutral or earth cables that you would not expect to be there due to the effects of parallel paths.
Having two seperate HV supplies in the building requires that you have a full understanding of the LV distribution through the building. It also requires that you have the installation set up in such a way that the LV is completely identified and can not be mistaken or otherwise altered or interchanged. If not properly segregated you could in theory end up accidentally backfeeding the other electrical system.
The neutral earth connections are also of concern as you can have circulation currents in there that could suprise the unwary. In an emergency would you be able to identify quickly where the power source was sourced from and how to isolate ? you can have currents in the neutral or earth cables that you would not expect to be there due to the effects of parallel paths.
