Im working on a project where we are going to be installing a few 250kw Fast Chargers for Electrical Vehicles. As part of this job we are getting a new service from the Local Power Company (LPC). As part of the new service the LPC will be providing the new transformer 13.8kV to 480V (300kVA) and we are paying them for it and then work they require to hook up the primary side. When this project was originally designed they has specd out a Delta-Wye transformer. The arc flash hazard calculations where then performed based on the information they provided and the transformer information they gave us.
Now that is close to actually starting the job, they are saying that they used the original transformer somewhere else and its no longer available (dont ask, i have no idea how that happens). They are saying they do have a Wye-Wye transformer sitting around that we can use.
Im not very familiar with Wye-Wye transformers or what if anything would need to be done if we were going to use it in place of the original Delta-Wye. Ive done some research and reached out to a couple of fellow engineers about this but no one really has a lot of knowledge on that type of transformer. From what I could find is that the primary and secondary neutral need to be grounded and they may need to be grounded through a grounding resistor depending on the fault current. How do i determine if a grounding resistor is needed? Are the primary and secondary neutral tied together then grounded or are they grounded separately, with the primary neutral going through a grounding resistor?
Is there any thing else i need to know about wye-wye transformers that i should be aware of that need to be considered since this was originally designed from a delta-wye transformer?
Now that is close to actually starting the job, they are saying that they used the original transformer somewhere else and its no longer available (dont ask, i have no idea how that happens). They are saying they do have a Wye-Wye transformer sitting around that we can use.
Im not very familiar with Wye-Wye transformers or what if anything would need to be done if we were going to use it in place of the original Delta-Wye. Ive done some research and reached out to a couple of fellow engineers about this but no one really has a lot of knowledge on that type of transformer. From what I could find is that the primary and secondary neutral need to be grounded and they may need to be grounded through a grounding resistor depending on the fault current. How do i determine if a grounding resistor is needed? Are the primary and secondary neutral tied together then grounded or are they grounded separately, with the primary neutral going through a grounding resistor?
Is there any thing else i need to know about wye-wye transformers that i should be aware of that need to be considered since this was originally designed from a delta-wye transformer?
