Distribution Transformer

Industrial, Substation & Distribution Tfr. Upto 22kV, Upto 11kV, Upto 33kV, ONAN A poly phase Distribution Transformers design is presented in which transformer output pores are accurately constructed in both voltage magnitude and relative phase angle. The design incorporates both main and auxiliary transformers that are used in unison to produce the accurately constructed phases. The main transformer permits rough phase adjustment to be made with the auxiliary transform permitting phase fine tuning. Such a design is particularly suitable in transformer approaches that require output phases that are of a number not evenly divisible by three.

Distribution transformers normally have ratings up to 2500 kVA, although some national standards can describe units up to 5000 kVA as distribution transformers. Since distribution transformers are energized for 24 hours a day (even when they don't carry any load), reducing iron losses has an important role in their design. As they usually don't operate at full load, they are designed to have maximum efficiency at lower loads. To have a better efficiency, voltage regulation in these transformers should be kept to a minimum. Hence they are designed to have small leakage reactance.

Distribution transformers are classified into different categories based on certain factors such as: • Mounting location - pole, pad, underground vault

• Type of insulation - liquid-immersed or dry-type

• Number of Phases - single-phase or three-phase

• Voltage class

• Basic impulse insulation level (BIL).