Transformers at power on the network can rip current energization which is significantly higher than the rated current of the transformer. Size current energization depends on the time of inclusion and of the remanent magnetism in the core. The currents that occur when you turn on the transformer to the network can sometimes be problematic with respect to protecting the transformer. Blown fuse at delivery or failure switch immediately after turning on the transformer causes doubt the correctness of the transformer. Inrush current can cause a number of other inconveniences on the network such as the impact on other transformers connected to the same bus, an increase in noise due to the large amount of transformer failure, increased occurrence of voltage drops in the network.