Substation Transformer Explained

A Substation Transformer is designed for installation on three-phase transmission and distribution systems. Substation transformers are constructed for in-door or outdoor mounting on a concrete pad with high and low voltage cables entering operating compartments through enclosed sidewall mounted bushings (unit-type transformers) or through cover or sidewall mounted bushings (opentype transformers).

Liquid-filled substation transformers are used in a wide variety of utility and industrial applications. These step-down transformers are usually manufactured in accordance with applicable IEEE standards. Substation transformers are most often offered with one of 3 different fluids: Mineral oil or silicone transformer oil. Primary voltages of a substation transformer usually ranges from 2.4 kV to 69 kV in 225 through 20,000 kVA sizes, but 600 volt through 35 kV secondary voltage ratings are also available.

An electrical substation is a part of the electrical installation that includes the terminations of the transmission or distribution lines and switchgear, and which may also include transformers The substation also typically includes all the necessary devices for control and protection. Depending on the function performed, it can be defined as a transforming, conversion, transmission or distribution substation. A MV/LV transformer electrical substation consists, therefore, of the set of devices dedicated to the transformation of the voltage supplied by the distribution network at medium voltage (e.g. 20 kV), into voltage values suitable for the power supply of the low voltage lines (e.g. 400 V).

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