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19 March 1999 Infrared thermography and overloaded neutral conductors
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Present findings of two recent case studies. One involves transformer failures on three computer-stores within eight hours of their grand opening. The second discusses the findings during an infrared thermography-training course for electric utility engineers of a transformer vault serving an industrial customer. Both of these deal with overloaded neutral conductors. Historically, the average neutral conductor carried only the imbalance of the current between the phases of a three-phase system. This current was typically small in relation to the load being served. In fact, for economic reasons many neutrals were installed smaller than their associated phase conductors. Today however, certain types of loads (non-linear loads such as computers) and certain transformer connections (4 bushing single phase with a collector bus) cause the neutral to have up to three times as much amperage as the phase conductors. This paper will discuss the conditions under which such loading occurs and further investigate steps that can be taken/recommended should an infrared test indicate an overloaded neutral conductor.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John McComb and Hector E. Niebla "Infrared thermography and overloaded neutral conductors", Proc. SPIE 3700, Thermosense XXI, (19 March 1999);

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