Harriet B. in Richmond. Working on a primary metered industrial account with Dominion Virginia Power. VT ratio should be 120:1 but bills indicate they're using 60:1 multiplier. Customer has 4.16kV service with PT ratio of 4160:120V. Anyone experienced VT multiplier errors on primary metering?
VT Ratio Error on Primary Metered Account
Ray C. Louisville here. VT errors are trickier than CT issues because fewer people understand potential transformer ratios. What does the meter nameplate show for PT ratio? Sometimes utilities mess up the 4160V vs 4800V calculations.
Ray - meter shows PT ratio 4160:120 which is 34.67:1, but multiplier should account for line-to-line vs line-to-neutral. I think they're using 60:1 when it should be 120:1 for line-to-line measurement.
Jim W. from Youngstown. Harriet, check if it's a three-phase four-wire vs three-wire metering issue. Primary metering configurations can get complicated with VT connections. What's the actual voltage being measured at the meter?
Jim - it's three-wire delta configuration. Meter reads about 4160V line-to-line as expected. The energy readings seem low compared to production schedules, which suggests under-registration from wrong VT multiplier.
Todd from Portland. Had similar VT issue with PGE on industrial account. Took 6 months to resolve because their metering department didn't understand primary PT configurations. Document everything and request formal meter test.
Thanks Todd. Dominion agreed to meter test after I provided detailed analysis. They found PT multiplier was indeed programmed wrong. Getting 8 months of credits for under-billing. Customer actually owes them money, but at least it's corrected now.