Power Factor Correction
I am not sure if this is going to work, but I have tried to attach an Excel file that will calculate the size of your penalty under ZESCO’s new Power Factor proposal – ZESCO Power Factor correction.xls
Start by filling in the 4 yellow cells – the charges for Maximum Demand, units (kWh), Fixed Monthly charge and the Exchange Rate. What I have put in there (when I saved the file) is my guess as to what might be approved by the ERB – the 300% increase is only what ZESCO has asked for.
Then fill in the 3 pale green cells – the cost of your PF correcting equipment, your monthly Maximum Demand and the amount of power you have used.- from your relevant ZESCO bill. Then the data in rows 11 to 41 will calculate the size of your penalty: for a given PF (before correction) in column A, Kwacha in column B, Dollars in column C and number of months to recover your investment in column D. Remember that if you are curing for 5 months of the year, and you have a 24 month payback time then it MIGHT take you 4.8 years to recover your money – although this equipment (especially if it is a general – transformer based – type) will save you some money even in the non-curing months.
A PF as low as 0.6 may appear pessimistic but, if Mr. Daka (area manager, Choma) is right, ZESCO will base this penalty on the WORST PF reading for the month, not the average. It COULD happen that, at the end of March you have done a lot of curing, but you switch off your fans on the 25th of the month. Then your grading lights are left on one night and the PF of florescent tubes could easily be as low as 0.6 – hence the penalty that you will pay.
One final point: in a paper presented to the Engineering Association of Zambia it is claimed that the cost of a kWh of power, generated by a diesel engine, is 41 US cents per kWh. From what I understand of this technology, it will save you diesel if you correct the PF of the load carried by your generator. I hope to demonstrate that with an experiment…..
I hope that helps,