Quick question for the group. I'm reviewing an OG&E account here in Tulsa and their billed demand charges don't seem to match what I'm calculating from the 15-minute interval data. The bill shows 425 kW billing demand but when I analyze the interval data, the highest 15-minute reading for the month was only 387 kW. The customer is on Schedule LMP and getting charged $12.85/kW for demand they apparently didn't use. Anyone know if OG&E has some kind of ratchet provision or minimum demand charge that might explain this discrepancy?
OG&E demand charges not matching interval data totals
Steve, check the OG&E tariff for demand ratchet provisions. A lot of utilities have a clause where your billing demand can't drop below 75% or 80% of the highest demand in the previous 12 months. So even if your actual demand this month was 387 kW, if you hit 500+ kW sometime in the past year, the ratchet might be keeping your billing demand artificially high.
Hank's probably right about the ratchet. We Energies here in Milwaukee has a similar provision where billing demand is the higher of current month actual demand or 65% of the peak demand from the previous summer months. It's designed to recover fixed costs even during low-demand periods. You'll need to look at 12 months of historical data to see if there's a ratchet in effect.