The HVAC system consists of many heat pumps and ventilation air units. There is no central chiller or water pumps anywhere. The largest motor in the school is probably 5-10 hp.
Details from one month's bill: consumption 108288 kwh demand metered 242 kw demand measured 321 kw Somehow the difference in metered and measured demand related to power factor.
Any thoughts how to determine the power factor from the given info. The utility claims measured demand = the metered demand * 0.85 / (actual pf). This gives actual pf = 0.56 NO WAY Another thought, Measured Demand is S, metered demand is P, this gives pf=0.75
Any thoughts why the power factor could be low? Any thought how to fix it. I am very hesitant to throw capacitors at the problems due to harmonic concerns and switching controls needed when going on / off backup generator.
I always start the investigation this way.
When was the power company meter last checked/ calibrated? They are not often wrong but it does happen. Ask for a new meter. Can not hurt. What was the last electrical project and when was it done. Does it corespond to any change in the electrical bill? How is the electricity being used? Big jump in the morning? Are the phases balanced? Do they have an energy man system to prevent all of the compressors turning on at the same time? How long has this been going on? What is the age of the building? How was the wireing done? Shared neutrals on the branch circuits? What size are the neutrals? Got any step down transformers? Are they connected correctly and giving the proper voltage? I had a brand new electrical distribution system installed in a building and the taps were set wrong for the incomming voltage. No one ever checked until the problems started.
Acquire an recording meter, RPM, Durants, BMI, and do at least 24 hours as close to the mains as possible. Check the readings against what you all ready have from the Power CO. Rentals are available, though it helps to have set one up a time or two. You might consider paying some one to come out and take the readings.
PF correction by capacitors will not help the harmonic issue. Only isolation transformers will help there.
Get up close and freindly with the rate structure. I know of places in CA where the billing structure has 25 line ltems. Including 6 for PF at different times of the day. You need to understand the structure. I have done billing software for years. I have a 3 page check list of information that the customer must sign and complete BEFORE scheduling a visit.
This problem MIGHT boild down to the utility system not being stiff enough for the loading.
I have a customer in down town LA that has a constant PF of 40-50. Printing presses are killers. If it was not for the generated power on site some 6 meg the bills would be out of site. They are getting hit for something like 30 k a month for PF charges.
Sorry I am asking more questions than answers.