Transformer innovators since 1945

Pre-magnetizing systems

Wesemann offers pre-magnetizing systems for power transformers regardless of the brand.

Our engineers can design a reliable and compact pre-magnetizing system based on the characteristics of your specific transformer.

The compact design includes switchgear with a terminal box for controlling and returning a status signal of the pre-magnetizing system. This way the pre-magnetizing systems can be conveniently placed close to the transformer, even if there is only a limited amount of space.


The problem

During the energizing process of power transformers in general problems can arise with high inrush currents up to sometimes 20 to 30 times the nominal current. This inrush period can take up more than 10 seconds and may cause a continuing heavy noise and also may cause physical tension on the construction of the transformers.

When a power transformer is used on a so called “weak network” (i.e. electrical network on board of a ship or oil rig) the inrush peak might be slightly lower because of the damping on the primary network.

This will reduce the needed amount of time required to magnetize a transformer. On the other hand the big disadvantage of this weak network is this damping effect. On offshore networks as well as for industrial networks some standards are applicable when energizing a transformer and these standards specifically limit the allowed inrush current. Next to the issue with these applicable standards in most cases the damping effect might result in the failure of other connected equipment on the power network. Most of the problems occur with the inrush currents caused by power transformers used on weak networks.


The solution

By pre-magnetizing a transformer before it is switched on you can prevent these high inrush currents. By implementing this procedure the transformer will be instantly energized without any damping on the supplying network. Besides this it also prevents heavy tension on the physical construction and main switch gear. The inrush current of the transformer will now be even lower than the nominal current.


Please contact our product specialists for additional information or a suitable solution.



Pre-magnetizing systems

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