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How SRP ensures your power quality

We work hard to provide reliable electric service, but all electrical systems experience occasional fluctuations in power quality. That’s why we have a Power Quality Services Team to help you prevent power interruptions and offer solutions if they happen.

Protect your electrical equipment with SRP Power Quality Services  

Power quality fluctuations like voltage sag, harmonics, voltage transients and spikes, and flicker can all cause damage to your electrical equipment. Our services, which include diagnostics, mitigation, monitoring and prevention strategies, can help you find and resolve the cause of power quality problems.  

Find the right service based on your power needs 

We offer "single-phase" or "three-phase" service depending on your power needs. Here are some tips to help you decide which service is right for you: 

Single-phase  Three-phase 
  • Often for homes and small businesses
  • Also known as a 120/240-volt service 
  • Often for large industries, shopping centers and even some large homes  
  • Usually required for equipment like air conditioners larger than 5 tons, commercial refrigeration, motors and pumps 

What causes power disturbances?  

A number of factors can cause power disturbances, including lightning strikes, a short circuit in your home wiring or a power system outage. Poor grounding and improper wiring can also contribute to home power quality problems.  

These disturbances can cause voltage surges and spikes that can damage sensitive electrical equipment and appliances. See the services we offer to help protect them. 

Common electrical equipment terms  

This list of terms and definitions outlines the different types of power quality disturbances you may experience.  

Distortion (harmonics)

Distortion occurs when harmonic frequencies are added to the 60 hertz (Hz) voltage or current waveform, making the usually smooth wave appear jagged or distorted. Distortion can be caused by solid state devices such as rectifiers, adjustable speed controls, fluorescent lights and even computers. 

At high levels, distortion can cause computers to malfunction and cause motors, transformers and wires to heat up excessively. Distortion is probably the most complicated and least understood of all power disturbances.


Flicker can be defined as small amplitude changes in voltage levels occurring at frequencies less than 25 Hz. Flicker is caused by large, rapidly fluctuating loads such as arc furnaces and electric welders. 

Flicker is rarely harmful to electronic equipment but is more of a nuisance because it causes noticeable changes in lighting levels.

Frequency deviations

Normal utility power in the United States is supplied at a frequency of 60 cycles per second, or 60 Hz. On large interconnected utility systems such as SRP's, frequency is very stable and deviations are rarely a problem.

However, on smaller power systems, especially those supplied by on-site generators, frequency deviations can cause electronics to malfunction and affect the speed of motor-driven clocks.


Interruptions occur when voltage levels drop to zero. Interruptions are classified as momentary, temporary or long-term. Momentary interruptions occur when service is interrupted but automatically restored in less than two seconds.

Temporary interruptions occur when service is interrupted for more than two seconds but is automatically restored in less than two minutes. Long-term interruptions last longer than two minutes and may require field work to restore service.

In some cases, momentary outages may go unnoticed or cause no apparent problems. However, even momentary outages can last long enough to shut down computers and disrupt the operation of sensitive electrical equipment.


Noise, or more specifically electrical noise, is a rapid succession of transients tracking up and down along the voltage waveform. The magnitude of these rapid transients is usually much less than that of an isolated transient.

Noise often originates in electrical motors and motor control devices, electric arc furnaces, electric welders, relays and remote atmospheric discharges, such as lightning.

Although less destructive than a large rapid transient, electrical noise can cause computers to malfunction and can interfere with the operation of communications equipment or other sensitive electronic equipment.


Transients are sudden but significant deviations from normal voltage or current levels. Transients typically last from 200 millionths of a second to half a second. Transients are often caused by lightning, electrostatic discharges, load switching or faulty wiring. 

Transients can erase or alter computer data, resulting in difficult-to-detect computational errors. In extreme cases, transients can destroy electronic circuitry and damage electrical equipment.

Voltage sags

A voltage sag is a short-duration decrease in voltage values. Voltage sags longer than two minutes are classified as undervoltages. Common causes of voltage sags and undervoltages are short circuits (faults) on the electric power system, motor starting, customer load additions, and large load additions in the utility service area.

Sags can cause computers and other sensitive equipment to malfunction or simply shut off. Undervoltage conditions can damage certain types of electrical equipment.

Voltage swells

A voltage swell is a short-duration increase in voltage values. Voltage swells lasting longer than two minutes are classified as overvoltages. Voltage swells and overvoltages are commonly caused by large load changes and power line switching.
If swells reach too high of a peak, they can damage electrical equipment. The utility's voltage regulating equipment may not react quickly enough to prevent all swells or sags.  

Still have questions or concerns? Call (602) 236-8888(602) 236-8888 or email help@srpnet.com.