The primary purpose of fire department personnel is to prevent fires. There is a lot of training in fire science, fire suppression, fire vehicle and equipment operation and maintenance, as well as providing emergency medical services. But I imagine almost everyone involved would admit that “putting the wet stuff on the red stuff” is the real thrill and enjoyment. 

It would probably seem a stretch to compare troubleshooting and mitigating a power quality problem to putting fires out, but there are some commonalities. Preventing the problem is the priority in both cases. 

Preventing PQ problems

Preventing power quality problems fits well into an effective electrical equipment maintenance program, such as what is covered in NFPA 70B, Standard for Electrical Equipment Maintenance. Note that since January 2023, NFPA 70B is a standard and no longer a recommended practice. NFPA summarizes 70B as providing details for preventive maintenance for electrical, electronic and communication systems and equipment—such as those used in industrial plants, institutional and commercial buildings and large multifamily residential complexes—to prevent equipment failures and worker injuries. The facilities mentioned are also where most power quality troubleshooting and monitoring programs are carried out. The last line could be replaced with “prevent equipment misoperation and equipment damage from PQ phenomena.” 

The 2026 revision of NFPA 70B has individual chapters for different types of equipment, each with sections on scope, frequency of maintenance and periodic maintenance procedures. Each type of electrical equipment, such as transformers and breakers, have their own chapter. Power quality issues can involve multiple types of equipment, as well as wiring, grounding, the weather and more. 

Since power quality isn’t a single entity, its specific information is in Annex J. It also expands the emphasizing of continuous monitoring technologies to augment traditional periodic inspections. Continuous power quality monitoring has long been recognized as critical to detect developing conditions before they turn into faults or equipment failures that can compromise productivity, equipment uptime and safety.

Completing a walk-through

Annex B has suggestions for inclusion in a walk-through inspection checklist. This concept can be applied to power quality. A good place to start is a walk (or drive) to inspect the power delivery system to the facility. A thermal scan can detect issues with the connections in the wiring and the power transformer. Verify that the transformer area is clear of any vegetation that can interfere with the cooling or cause a fault condition. This is true all along the utility distribution system in the area. Improper clearance of vegetation from the distribution lines is a significant cause of power quality disturbances, especially during high wind, high temperatures and storms.

The next stop on the walk-through inspection is inside the facility, where the bus bars lead to electrical protection equipment. A thermal scan here can also reveal connections that need tightening and breakers running hotter than others. Voltage and current metering on the facility side of the point of common coupling, as well as at various distribution panels within the facility, can reveal voltage and current imbalance conditions. 

It is not uncommon for electrical loads to be added, subtracted or relocated on the branch circuits, creating current imbalance conditions. A current imbalance will usually result in a voltage imbalance. This may make equipment on the lower voltage phase more susceptible to voltage sags, as well as causing overheating in three-phase motors.

The changing of equipment and wiring is often not reflected in the facility’s one-line diagrams, and it may have been done without consideration of the effect on equipment susceptible to sags and harmonics generated by certain loads. 

It is good practice to maintain a log of measurements of critical power parameters on the circuits that carry large and susceptible loads. Any measuring or monitoring with a PQ instrument must be carried out with full compliance to the manufacturer’s instructions and NFPA 70E, Standard for Electrical Safety in the Workplace. Review the log of trends for any significant increase in harmonics and interharmonics or changes in the nominal levels of voltage, current and power factor. Of course, having the previously mentioned continuous monitoring system in place would simplify this task and provide a more timely response to changing situations.

Just like each type of equipment has frequency of maintenance in 70B, so should the PQ walk-through. The critical nature of continued operation of the facility and cost of downtime are major factors in determining the schedule. At a minimum, it should occur during each of the seasons in regions where the temperature and weather conditions vary significantly. Whenever there is a significant change to the electrical infrastructure, it should be carried out before and after the changes. This includes when photovoltaic systems are installed on the roof or property of the facility. 

While it may seem like a lot of work without immediate payback, consider this paraphrase of Smokey Bear’s catchphrase: ”Only you can prevent power quality fires.”

stock.adobe.com/Prasong Takham