apowerengr... i agree, it should have been a predictable issue. However, i've walked into a multitude of existing problems while designing additions and alterations to the existing system. The ungrounded delta and surge arrestor problem is but the tip of the iceberg. I found (4) 2500kva...
Thanks for the reply. I agree... the xfmr is backwards from what it should have been. I was able dig out the original contract drawings this morning... looks like the design shows the transformer having a delta winding on the 27kV side... so... either engineering error or cad error... either...
I'm involved in a project where the existing plant distribution is 27kV with a 5kV standby generator. The plant receives power from the utility’s 27kV grounded wye distribution system. The step up transformer between the 27kV bus and the 5kV bus has a delta ungrounded primary, (27kV), and...
Thanks for everyone's input. The biggest issue is the class 1 div 1 location. The solution is to install a manhole immediately adjacent to the screen vault and route all circuits, unspliced from each piece of equipment, through sealoff fittings into the new manhole. Once outside of the Class...
Thanks for the information. One small detail i purposely left out is the fact that the vault and screen area is Class 1 Div 1... and since we cannot install anything above grade, there is no ventilation to lower the classification. However, the req'd conduit seals will benefit by keeping water...
If your data center is built per NFPA 75 and the electrical installed according to Art 645 in the NEC (NFPA 70), then the frames of the racks are required by code to be grounded separately from the cord and plug. Typical grounding arrangements would be a bare 2/0 grounding conductor run under...
be careful... i think that would be a class 2 transformer, (it's been a while since i last checked code on this)... but the largest acceptable transformer for DDC controls in an environmental air plenun is 96va. If i can find the manufacturer and part number, i will post it. I originally put...
First... I'm new to this site, so please bear with me...
I have been asked to look into waterproof terminations / submersible junction boxes for a waste water screen project. Our client has a waste water screen located in a vault about 30 feet fom the Ohio river. When the river over runs it's...
