At present, the general circuitry of above of 110 kv voltage class as transmission lines, up to and including 35 kv voltage circuit as a power distribution line. More than 110 kv transformer used in power supply system laid 35 kv, 110 kv transmission voltage 20 kv and 10 kv distribution voltage, for the use of the user or public distribution transformer. Large YongDianHu will also have 110 kv transformer of transformer as a user. Small power plant are also useful as grid voltage is 110 kv, so use 110 kv transformer as a step-up transformer. Commonly used 110 kv transformer capacity in the range of 110 ~ 63000 kva, most with 31500 kva power system.