The company I'm working with is in the very early stages of design for a plant that will use 5-10 MVA at 4.16 kV. I understand that above a certain size, the utility may require a customer-operated substation instead of providing pad-mount transformers. This plant will be comprised of two identical structures, each using half of that power. We would obviously much prefer to have two pad-mount transformers, each servicing one of those structures, rather than incurring the capital and operating expenses associated with a substation. The nature of the loads means power factor is not a concern. I'm interested in anyone's experience with this type of situation. I know no one is going to be able to give me a definitive answer and it's going to depend on which utility and many other design considerations, but I'm just looking for a sanity check at this point.
Substation or multiple pad-mount transformers for >5 MVA
- Thread starter EC Dan
- Start date
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Does the PoCo demand one service to the entire plant or could it be one service to each building?
JoeStillman
Senior Member
- Location
- West Chester, PA
- Occupation
- Electrical PE
You can do two customer-owned padmounts. Probably cost a lot less than a substation.
We are too early to get PoCo input, the site is not selected. I'm just trying to get an idea of what we can expect and whether it's reasonable to use two independent pad-mount transformer-fed services as our base case instead of a single substation fed-service.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Does the utility require an actual customer owned substation, or simply customer owned MV equipment?
Many utilities limit the amount of power they will provide at 480V, also called secondary metering, above that point they require customers to purchase medium or distribution voltage, also called primary power.
My experience is the utilities typically do not care if you use padmount switches/metering and transformers, or if you create an actual substation. Although they may require an open air metering and disconnect if they feed your facility via poles.
Many utilities limit the amount of power they will provide at 480V, also called secondary metering, above that point they require customers to purchase medium or distribution voltage, also called primary power.
My experience is the utilities typically do not care if you use padmount switches/metering and transformers, or if you create an actual substation. Although they may require an open air metering and disconnect if they feed your facility via poles.
Depends on who wants, or is willing, to own the transformers. We have done a primary feed into vista switches with primary metering, and then multiple customer owned 12.47->480 pad mount transformers at this scale. But it could also be multiple utility owned pad mount transformers at this scale, I have a customer with (4) 2500 kva utility owned transformers.