Easier Than A, B, C
Tip written by: Infraspection Institute
When performing infrared inspections of electrical distribution systems, many people identify the individual phases of polyphase circuits as A, B, and C; others frequently use 1, 2, and 3.
Confusion can arise with alphabetical or numerical labels particularly when switchgear enclosures are inspected from different perspectives e.g. front versus rear. Further confusion can occur when phase rotation has been modified or changed or, in some cases, mislabelled.
Reference errors can be avoided by using terms that cannot be confused such as Left, Middle, Right OR Upper, Middle, Lower. When using such terms, one should always reference where the image was taken from. For outside power lines references such as Street, Center, and Field may be used to identify phases without confusion.
Using the above simple terms can make your reports easier to understand and help to eliminate confusion when repairs are performed.
Infrared inspection of electrical distribution systems is one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
January 18, 2021
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Frequency of Infrared Inspections of Electrical Equipment
Tip written by: Infraspection Institute
“How often should electrical systems be thermographically inspected?” Historically, accepted industry practice has recommended that infrared inspections be performed annually; however, site specific conditions may dictate considerably shorter intervals for some equipment or facilities.
According to the 2010 Edition of NFPA 70B Recommended Practice for Electrical Equipment Maintenance, “Routine infrared inspections of energized electrical systems should be performed annually prior to shutdown. More frequent inspections, for example, quarterly or semiannually, should be performed where warranted by loss experience, installation of new electrical equipment, or changes in environmental, operational, or load conditions.”
Semi-annual infrared inspections may also be prudent where unscheduled outages of electrical equipment could pose significant environmental or safety hazards, or result in catastrophic damage to other systems or components.
Because infrared inspections are only effective when electrical system components are energized, it is imperative to perform infrared inspections when subject equipment is operational. For facilities with seasonal equipment such as heating and cooling systems, it may be necessary to schedule infrared inspections on several different days spread throughout the calendar year.
As always, infrared inspections of electrical systems should only be performed by properly trained and certified thermographers following all appropriate safety precautions. For information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, contact Infraspection Institute at 609-239-4788 or visit us online at: www.infraspection.com.
To obtain a copy of NFPA 70B, contact the National Fire Protection Association at 1-800-344-3555 or visit them online at: www.nfpa.org.