What is power quality?

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.

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What is a power quality disturbance?

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.

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Why is power quality so important?

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.

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Shouldn't I expect We Energies to provide me with flawless power?

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.

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What are the different types of power disturbances I can experience?

There are several types of power quality disturbances that occur on electric power systems. The occurrence of a power quality disturbance may or may not impact end-use electrical equipment, depending on the magnitude, time duration and sensitivity of said end-use equipment. By far, the most common type of power quality disturbances to occur are voltage sags followed next by interruptions and transients.

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What are the causes of power quality disturbances?

There are various causes for the different types of power quality disturbances. The most common type of power quality disturbance are voltage sags. Voltage sags are commonly caused by short-circuit faults on an electric power system. Short-circuit faults can originate on the transmission system, distribution system and/or inside facility/home electrical power systems. Short-circuit faults also tend to result in interruptions, which is another disturbance type.

Certain disturbances may also arise from normal operations on an electric power system. One example is capacitor bank energization. When a capacitor bank energizes, it inevitably results in a voltage transient response. Most of the time, this transient response does not adversely impact electrical equipment. However, certain sensitive electrical equipment may alarm and/or shut-down when transients are detected. Transients also occur as a result of lightning contact with an electric power system, electric loads turning ON and/or OFF, circuit switching and electrical faults.

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How do I know if my business is at risk of power quality disturbances?

Some symptoms that a facility/home has experienced a power quality disturbance include:

• Dimming/flickering lights
• Random shut-down of electronics
• Tripped circuit-breaker
• Damaged electrical equipment
• Alarms/alerts from electrical equipment

The most certain way to confirm the occurrence and/or presence of a power quality disturbance is through power quality monitoring in order to record data on the disturbance and correlate it with the date and time of observed symptoms.

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What steps can I take to protect my facility’s/home’s electrical equipment from power quality disturbance?

The first step is to understand what types of disturbances occur on an electric power system and how that compares with the compatibility levels of end-use electric equipment. This step will help identify any potential gaps in equipment compatibility and better understand its vulnerabilities to potential disruption and/or damage. All facilities/homes can stand to benefit from proper surge protection application. Surge protection is an effective way to avoid permanent damage to electrical end-use equipment and other parts of the electric system due to high magnitude impulse transients. Additionally, line-conditioning equipment such as UPS’s, Dynamic Sag Correctors and Line Reactors are effective ways to protect equipment from other types of disturbances that occur on electric power systems.

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How does We Energies investigate a customer's power quality?

If you suspect you may have a power quality issue and/or concern and you have not been able to identify its cause, contact We Energies to discuss your issue/concern. We have specialists within our company that understand the technical aspects related to power quality and equipment compatibility. We Energies has a number of resources at its disposal to help investigate your concerns and provide the appropriate guidance.

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How can I get help?

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

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