Abstract:
Temperature rise tests on standard single-phase, oil-filled distribution transformers are compared for sinusoidal and nonsinusoidal current conditions. In addition to a s...Show MoreMetadata
Abstract:
Temperature rise tests on standard single-phase, oil-filled distribution transformers are compared for sinusoidal and nonsinusoidal current conditions. In addition to a stock 50 kVA unit, two 25 kVA transformers were specifically constructed with embedded thermocouples that permitted the true hot-spot temperatures to be measured under load. Test results show that when subjected to full-load currents having low-order harmonic distortion values up to 40 percent THD, the average winding temperature rise is 2 to 7/spl deg/C hotter than for full-load sinusoidal currents. The greatest difference recorded between the average winding temperature and the hot-spot temperature was 7/spl deg/C, significantly less than the 15/spl deg/C allowance given in the standards. This study indicates that the present standard for sizing small distribution transformers supplying nonsinusoidal currents appears to provide good estimations of load capability.
Published in: IEEE Transactions on Power Delivery ( Volume: 11, Issue: 1, January 1996)
DOI: 10.1109/61.484027
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