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Discussion Starter · #1 ·
Power transformer with inferior core
A power transformer manufacturer which was located in economical boycotted country met some problems in material provision.
The core material and some other things shall be supplied by a foreign company that they work under its license. While boycotting duration they got to use inferior material in core transformer construction. Whereas they didn't have adequate base knowledge of transformer design, they followed all construction algorithms that were dictated by foreign company. They thought this instruction deviation only influenced the power losses of transformers, but in practice they found other important problem about short circuit withstand of transformers. The power transformers windings sometimes were damaged mechanically due to a sever short circuit fault current.
What is your opinion? How core material selection influenced the transformer withstand against short circuit current?
 

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Discussion Starter · #2 ·
I remember one of our physics tests at school many years ago. Our teacher had provided one solenoid with a magnetic bar in the center; He put one metallic ring on magnetic bar and connected terminal of the coil to 50HZ, 220V power supply. Suddenly, we observed a wonderful phenomenon. The metallic ring jumped up and stood over the magnetic coil.
We had to explain the reason of that phenomenon. I think if our teacher had replaced solenoid magnetic rod with an other inferior core, we would have observed a higher jumping.
Indeed, the applied force to the metallic ring is similar to the transformer winding stresses which meet short circuit fault currents.

BEST REGARDS
M.S.J
 
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