Title :
Temperature rise of small oil-filled distribution transformers supplying nonsinusoidal load currents
Author :
Galli, A.W. ; Cox, M.D.
Author_Institution :
Dept. of Electr. Eng., Louisiana Tech. Univ., Ruston, LA, USA
fDate :
1/1/1996 12:00:00 AM
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°C hotter than for full-load sinusoidal currents. The greatest difference recorded between the average winding temperature and the hot-spot temperature was 7°C, significantly less than the 15°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
Keywords :
IEEE standards; distribution networks; harmonic distortion; power system harmonics; power transformer insulation; power transformer testing; power transformers; temperature distribution; temperature measurement; thermocouples; transformer oil; transformer windings; 25 kVA; 50 kVA; average winding temperature rise; full-load currents; hot-spot temperatures; load capability; low-order harmonic distortion; nonsinusoidal load currents; oil-filled distribution transformers; sinusoidal load currents; standards; temperature difference; temperature rise tests; thermocouples; Current supplies; Distortion measurement; Electric vehicles; Harmonic distortion; Mass production; Power industry; Temperature distribution; Temperature measurement; Testing; Transformers;
Journal_Title :
Power Delivery, IEEE Transactions on
