MILLING OPERATIONS understanding of the efficiency of the plant's electrical system indicating how much power supplied by the power supplier will perform useful work. As PF approaches unity (1), efficiency is improving, and power loss or reactive power is minimized. This benefits both the electric company and the miller. As presented earlier, an electric rate may include additional charges when the customer has a PF less than some preset limit, perhaps between 80% and 90%. Rather than paying the PF penalty, consider installation of PF correction devices. A reported example was a normal demand charge of $5 per kW per month with a PF penalty increase adding $2 per kW to the charge for a total of $7 per kW per month. The PF penalty can be a significant part of a mill's energy cost. Monitoring PF A power quality analyzer or power analyzer that measures both working power (kW) and apparent power (kVA) is required to calculate the PF. As reported by Yokogawa (www. yokogawa.com), total PF on a three-phase, four-wire system may be measured using a watt meter for each line (3) and a multimeter to measure volts and amps on each phase line. PF is then calculated by dividing the total watts from each meter by the total volt-amps. Using three-watt meters will eliminate errors in measurement and calculation of PF in case of an unbalancedhttp://www.yokogawa.com http://www.World-Grain.com