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Utility Transformer Brokers (UTB) is a supplier of Used, New, Reconditioned, and Rewound oil filled Transmission & Distribution Auto transformers. UTB keeps a large supply of Auto transformers in our database that are in stock and ready to ship at a moment’s notice.
Auto Transformers are used to step-down or step-up voltage on a transmission or distribution system. They have only one winding per phase that is used as the primary & secondary winding of the transformer. In a conventional transformer there are two winding per phase, one for the primary and one for the secondary. The advantage of using an auto transformer is that they are smaller in size and are less expensive because less copper is used in the windings. The disadvantage is that they do not provide electrical isolation between its windings as a conventional transformer does, so it is limited to the applications it can be used for. Auto transformer also have limitation of not suppressing harmonic currents and are typically supplied with a buried tertiary to absorb some harmonic currents.
Autotransformers are typically used to interconnect systems operating at different voltage classes or can be supplied with a load tap changer to act as a voltage regulator on long rural distribution lines.
Manufacturers of Auto transformers include: ABB, Kuhlman, Central Maloney, Siemens, Ferranti Packard, Westinghouse, Allis Chalmers, RTE/ASEA, Uptegraff, McGraw-Edison, Howard, Cooper, GE, Prolec, Waukesha, Virginia, Pennsylvania, WEG, Hyundai, and Delta Star.
Typical base ratings for Auto transformers are: 2.5 MVA, 3.75 MVA, 5 MVA, 7.5 MVA, 10 MVA, 12 MVA, 15 MVA, 18 MVA, 24 MVA, 30 MVA, 45 MVA, 50 MVA, 60 MVA, 75 MVA, 90 MVA, 100 MVA, 120 MVA, 132 MVA, 150 MVA, 200 MVA, 225 MVA, 300 MVA
Typical high voltage ratings for Auto transformers are: 345000 Wye, 230000 Wye, 161000 Wye, 138000 Wye, 115000 Wye, 69000 Wye, 46000 Wye, 34500 Wye, 24940 Wye, 13800 Wye, 13200 Wye, 12470 Wye Typical low voltage ratings for Auto transformers are: 230000 Wye, 161000 Wye, 138000 Wye, 115000 Wye, 69000 Wye, 46000 Wye, 34500 Wye, 24940 Wye, 13800 Wye, 13200 Wye, 12470 Wye, 4160 Wye