August 2022 Volume 4

MAINTENANCE

Reducing or Avoiding kVAR and Peak Demand Charges -- We have discussed two of the more significant charges that are itemized on an industrial electrical utility bill. Now we will look at how to avoid them. • Power Factor Improvement -- Power-factor is a property of the machinery being powered, is unique to the customer, and is completely within control of the customer to affect it. A machine need-not have a poor PF, but many types of older machines were designed when PF billing did not exist. Improving PF can be a matter of improving machine design and/or installation of mitigation equipment. The first steps to improving PF are to determine if it is a significant charge on the utility bill, identify which machinery is the source of the poor PF and then calculate the return on investment for the equipment to correct the PF. There are many experienced consultants who can perform internal electrical power audits with the goal of identifying and improving poor PF conditions.

it is more economical to leave a motor running between production intervals); and identify equipment that can be improved through engineering to reduce the demand during starting and operation. (An example of this is to use a ‘Soft Start’ motor controller on a forging press motor to reduce the high initial demand during starting.)

Figure 3. Measured kW demand of a 750 kW induction heater

Competitive Energy Procurement Thanks to energy deregulation, electrical power (and gas) is bought and sold as a commodity. In several states such as Ohio, Pennsylvania and Illinois, electrical power can be purchased competitively through auctions and contract negotiations. Several firms exist to partner with industrial customers to give the customer more competitive options on bulk energy purchases[4].The benefit of an energy purchasing partner extends into reducing peak demand charges. Many firms can forecast periods of high peak-demand rates and provide guidance to clients as to when the periods are expected to occur. This gives the utility customer the opportunity to temporarily curtail electrical usage until the period of high peak charges has passed, then resume normal production rates.

Figure 2. Measured lagging demand of a 750 kW induction heater • Peak Demand Avoidance -- Electrical demand billing is not only a result of machinery design, as with power-factor, but is also affected by production scheduling and utility billing structure[3]. Knowing the source of high demand is important, and engineering changes can be made to reduce the demand a machine puts on the utility. Some actions are to reviewmachine/production start-up procedures and identify times when multiple processes start simultaneously, leading to a high peak demand condition; reduce the unnecessary starting and stopping of large motor loads (sometimes

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