1LUS010001 LFE_ParallelOperTrans - دانلود رایگان
دانلود رایگان تعداد صفحه : 8Scope This leaflet contains general procedures to be followed from the time the
دانلود رایگان
| 1LUS010001-LFE_ParallelOperTransScope This leaflet contains general procedures to be followed from the time the transformer and its accessories are received, until it is put into operation. These instructions do not purport cover all possible contingencies that may arise during installation, operation, or maintenance, and all details and variations of this equipment. If you require additional information regarding this equipment, contact ABB Small Power Transformers in South Boston, Virginia. The theoretically ideal conditions for paralleling transformers are: Identical turn ratios and voltage ratings. Equal percent impedances. Equal ratios of resistance to reactance. Same polarity. Same phase angle shift. Same phase rotation. Single-Phase Transformers For single-phase transformers, only the first four conditions apply, as there is no phase rotation or phase angle shift due to voltage transformation. If the turns ratio are not same a circulating current will flow even at no load. If the percent impedance or the ratios of resistance to reactance are different there will be no circulating current at no load, but the division of load between the transformers when applied will no longer be proportional to their KVA ratings. Three-Phase Transformers The same conditions hold true for three phase transformers except that in this case the question of phase rotation and phase angle shift must be considered. Phase Angle Shift Certain transformer connections as the wye-delta or wye-zigzag produce a 30º shift between the line voltages on the primary side and those on the secondary side. Transformers with these connections cannot be paralleled with other transformers not having this shift such as wye-wye, delta-delta, zigzag-delta, or zigzag-zigzag. Phase Rotation Phase rotation refers to the order in which the دریافت فایل جهت کپی مطلب از ctrl+A استفاده نمایید نماید |