Questions and answers


Power quality refers to compatibility. It is the concept of powering and grounding electric equipment in a manner that is suitable to its operation. When your equipment operates as intended and without disruption, there is a compatible environment between the power source and the end use.

A power quality disturbance is any change in the power (voltage, current or frequency), that interferes with the normal operation of electrical equipment. There are several power quality disturbance types, which may be manifested in many ways. These events may cause lights to flicker, circuit breakers to trip, alarms to sound, processes to shut down, etc.

Power quality disturbances have been present since we began using electrical energy; however, yesterday’s equipment was more forgiving of disturbances than today’s. As manufacturers continue to reduce the size of circuits and components within their equipment, they are also reducing the voltage required to supply these components. The result is equipment that is faster and more powerful, but also more sensitive to power fluctuations.

Power quality is very important to anyone who relies on equipment and systems that are sensitive to electrical disturbances. The impact of power quality disturbances can be substantial — even the smallest variation can have significant implications for your business in the form of lost time, productivity and revenue.

We strive to maintain steady state voltage within limits established by the Public Service Commission of Wisconsin (PSCW). However, all electric distribution systems are subject to occasional voltage variations. These short-term disturbances, even when within PSCW limits, can sometimes cause sensitive electrical equipment within your facility to operate incorrectly.

We work hard to minimize the quantity and duration of power disturbances on its system. However, if you think your business is at risk because of these events, contact us for help in identifying and resolving your power quality concerns. Our company experts and trade partners will guide you through the assessment and resolution of your power quality problems.

There are several types of power disturbances that may affect your business. These may or may not impact you, depending on the magnitude, frequency and duration of the event, as well as the sensitivity of your electrical equipment.

Normal operation of the utility system is responsible for creating some power quality disturbances. But only a small portion of our customers are truly impacted by these events. While extensive system improvements could potentially limit — but not eliminate — these occurrences, this approach is impractical due to the tremendous costs that would be incurred by all of our customers.

The majority of power quality disturbances originate from conditions within the business or industrial facility. Large motors, arc welders, fluorescent lights, variable speed drives and even copiers and fax machines can all create power disturbances that negatively impact your operations.

If you have ever experienced any of the following, you may have a power quality concern:

  • Lights dim or blink
  • Personal computers shut down, lock up and/or restart
  • Equipment mis-operates at the same time each day
  • Circuit breakers trip without being overloaded
  • Equipment fails during thunderstorms
  • Automated systems stop for no apparent reason
  • Electronic systems fail to operate
  • The operation of one piece of equipment appears to affect the operation of another
  • Transformers and other equipment overheat without being overloaded
  • Alarms on individual pieces of equipment are activated

Most problems are either internal equipment problems or customer wiring problems. Other problems may be external to the facility. You may also have problems at one piece of equipment that is related to the operation of other equipment in your facility. Steps for troubleshooting power quality disturbances should be addressed in the planning stages so that you can resolve the problem both effectively and efficiently.

Because we are mandated to ensure that our delivered power meets legal specifications, we should always be the "first responder" to all your power quality investigations. View a diagram that illustrates the steps we take to help customers resolve their power quality problems.

Call us to help you identify and solve your power quality and equipment-compatibility challenges: 800-714-7777 ext. 7700.