Working with a primary metered client in Fresno served at 13.2kV. PG&E bills show VT ratio of 120:1 but I think it should be 110:1 based on the system voltage. This would mean we're being overbilled on both demand and energy. Schedule E-19 rate makes this expensive. Anyone dealt with VT ratio disputes on primary metered accounts? The math gets complicated fast. - Dan
VT Ratio Error on Primary Metered 13.2kV Service
Dan, VT ratio errors are tricky because they affect both energy and demand calculations. Dominion Energy had our client wrong for two years - 138kV system metered with 115kV ratios. Had to bring in a consulting engineer to verify the correct ratios against IEEE standards. Don't attempt this without professional backup. - Sandra P.
Check the actual VT nameplates if you can access them safely. FPL tried to tell us the ratios in their billing system were correct until we provided photos of the actual equipment showing different ratios. Sometimes the records are just wrong from original installation. - Manny G.
Had similar issue with APS on a 12.47kV service in Scottsdale. The VTs were correct but programmed wrong in the AMI system. Took a formal engineering study and six months of back-and-forth to get resolution. $340K refund was worth the hassle though. - Gina M.
Dan, Idaho Power requires a licensed electrical engineer to certify VT ratio calculations for primary metered disputes. Might be similar in California. The PUC won't consider customer complaints on primary metering without professional engineering review. - Mike S.
What's the actual system voltage measuring? If it's consistently 13.2kV then 120:1 might be correct. But if it's running lower like 12.8kV average, then 110:1 would be more appropriate. Central Maine Power had a similar discrepancy that required six months of voltage monitoring to resolve. - Diana R.
Portland General Electric uses 120:1 ratios on their 13.2kV distribution system as standard. Might check what PG&E's standard practices are before assuming it's an error. Sometimes utilities use conservative ratios to account for system voltage variations. - Craig P.
Any update Dan? I've got a similar situation with NYSEG on a 13.8kV service. They're using 115:1 ratios but I'm questioning if it should be 120:1. Waiting to see how your case turns out before deciding whether to pursue. - Lee B.
Lee, be careful with primary metering disputes. Eversource burned me on one where I was absolutely sure the ratios were wrong but turned out the customer's power factor correction equipment was affecting the readings. Cost more in engineering fees than we saved. Make sure you understand the whole electrical system first. - Vince S.
Primary metering ratio disputes require extreme diligence. Dan, you need a qualified power systems engineer to verify not just the VT ratios but also the CT ratios and meter programming. These systems are complex and errors can compound. Document everything and be prepared for a long process - PG&E will require substantial proof before admitting error on primary metered accounts. The potential financial impact makes it worth doing right though. - Randy D.
Thanks everyone. Hired a consulting engineer who confirmed the VT ratios are actually correct at 120:1 for this system voltage. The issue was my calculation error - forgot to account for system regulation. Sometimes the utility is right! Expensive lesson learned. - Dan