Why Are We Concerned about Power Quality?

The ultimate reason that we are interested in power quality is economic value. There are economic impacts on utilities, their customers, and suppliers of load equipment. 

The quality of power can have a direct economic impact on many industrial consumers. There has recently been a great emphasis on revitalizing industry with more automation and more modern equipment. This usually means electronically controlled, energy-efficient equipment that is often much more sensitive to deviations in the supply voltage than were its electromechanical predecessors. Thus, like the blinking clock in residences, industrial customers are now more acutely aware of minor disturbances in the power system. There is big money associated with these disturbances. It is not uncommon for a single, commonplace, momentary utility breaker operation to result in a $10,000 loss to an average-sized industrial concern by shutting down a production line that requires 4 hours to restart. In the semiconductor manufacturing industry, the economic impacts associated with equipment sensitivity to momentary voltage sags resulted in the development of a whole new standard for equipment ride-through (SEMI Standard F-47,  Specification for Semiconductor Process Equipment Voltage Sag Immunity).

The electric utility is concerned about power quality issues as well. Meeting customer expectations and maintaining customer confidence are strong motivators. With today’s movement toward deregulation and competition between utilities, they are more important than ever. The loss of a disgruntled customer to a competing power supplier can have a very significant impact financially on a utility.

Besides the obvious financial impacts on both utilities and industrial customers, there are numerous indirect and intangible costs associated with power quality problems. Residential customers typically do not suffer direct financial loss or the inability to earn income as a result of most power quality problems, but they can be a potent force when they perceive that the utility is providing poor service. Home computer usage has increased considerably in the last few years and more transactions are being done over the Internet. Users become more sensitive to interruptions when they are reliant on this technology. The sheer number of complaints require utilities to provide staffing to handle them. Also, public interest groups frequently intervene with public service commissions, requiring the utilities to expend financial resources on lawyers, consultants, studies, and the like to counter the intervention. While all this is certainly not the result of power quality problems, a reputation for providing poor quality service does not help matters.

Load equipment suppliers generally find themselves in a very competitive market with most customers buying on lowest cost. Thus, there is a general disincentive to add features to the equipment to withstand common disturbances unless the customer specifies otherwise. Many manufacturers are also unaware of the types of disturbances that can occur on power systems. The primary responsibility for correcting inadequacies in load equipment ultimately lies with the end user who must purchase and operate it. Specifications must include power performance criteria. Since many end users are also unaware of the pitfalls, one useful service that utilities can provide is dissemination of information on power quality and the requirements of load equipment to properly operate in the real world. For instance, the SEMI F-47 standard previously referenced was developed through joint task forces consisting of semiconductor industry and utility engineers working together.