For oil-immersed transformer, how to determine the top up?

Transformer oil fill is no absolute standard. Tubing, can observe the normal standard pillow top oil is not less than the minimum bit tick, tick no higher than the highest bit. In general, the oil immersed distribution transformer is not running, the oil level in the fifth to one-third of the tubing, tubing run oil level in half at Also, thermal expansion and contraction caused by the ambient temperature influence oil level.