Alice from Omaha. Found something unusual. Client is being served at 13.8 kV primary voltage but the demand on their bill appears to be measured at secondary voltage through transformer losses that are added back. The effect is they are paying demand charges on more kW than they actually draw at the service point. This seems like a measurement approach question rather than a meter error. Has anyone encountered billing at a different voltage level than the actual service?
Client's demand is being measured at the wrong voltage level
Derek from Charlotte. This is a known issue in some territories called high-side versus low-side metering. When the utility meters at the transformer secondary some tariffs require an addition to the measured demand to account for transformer losses. If your client is metered at primary voltage they should not have those additions.
Derek, how do I confirm which metering point applies to my client?
Derek again. Request the utility's service records for that account showing the meter location. It should specify whether the meter is on the primary side or secondary side of the step-down transformer. Then compare against the tariff's billing language for accounts served at primary voltage.
Greg from Columbus. Primary voltage metering with a transformer loss addition is actually a standard tariff provision in many territories. The question is whether the loss factor being applied is correct. Some utilities use a standardized loss factor that overestimates actual losses for newer, more efficient transformers.
Alice here. The transformer serving my client is relatively new — installed about 5 years ago. Could the loss factor be outdated?
Greg again. Yes. If the tariff's standard loss factor was established based on older transformer efficiency standards it may overstate losses for a newer unit. You can argue for an actual loss measurement rather than the standard factor. This requires a load flow study but on a large account the cost can be justified.