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Distribution transformer vs. Converter transformer

What is the  difference between a standard distribution transformer and  a converter transformer?

The design of a converter transformer due to its application and the presence of high harmonic content loads is totally different compare to the standard distribution transformers.

It is very important to inform your transformer supplier about the effective use of your transformer.

By using standard distribution transformer as a rectifier transformer you are risking to damage it  without being able to use the manufacturer product warranty!

We prepared a short technical description of the main differences between both types of transformers.

Converter transformer must face high harmonic contents in the voltage and in the current loads. For that reason  the magnetic core is oversized reducing at the same time  the working induction.

The medium voltage windings have to compensate additional losses due to harmonic contents and basing on the converter bridge type they are oversized too.


The converter bridge may cause also overvoltage causing a stress effect on the secondary side. To avoid this negative aspect  the low voltage insulation level has to increase.

All converter transformers are provided with an electrostatic screen linked to the ground  between the primary and secondary windings. The screen is very useful against the capacitive effect arriving from the secondary windings and reduces   at the same time the transmission of interferences between  the primary and secondary coils.

In an emergency situation it is possible to utilize a standard distribution transformer as a converter transformer, if it is equipped with electrostatic screen and  by decreasing its nominal power ( example 1250 kVA – 1000 kVA). Please consider this solution as a temporary as far the reliability  and the life time of distribution transformer used in this  way may be compromized. If necessary consult the Manufacturer for advice.

For further question do not hesitate to get in touch with our office at office@powerfullstop.com

Stay tunned at www.powerfullstop.com

Anna Krol
Marketing Manager by Power sp. z o.o.