How to build a 22kW charging station + soft starter for a 25kVA transformer

Posted by Sebastian Dehne on Sunday, October 11, 2015

To enable faster charging of our EV, I needed 3 phase 400V. But in Norway, most houses only get 3 phase 230V (IT earthing system). In order to get 400V, a transformer is needed. In this project, you can see how I built my own 22kW charging station using a cheap second hand transformer. I will also show you how you can soft start such a transformer to overcome the problem of high inrush current.

In the previous post, I showed you how to solder those thermal fuses without damaging them.

Credits go to the helpful guys from the EEVBlog forum for helping me building this.

High res photos

Here are some close up photos:

The terminal block on top is the primary side. The terminal at the button is the secondary side. The neutral output is connected to ground.

25kVA dYN transformer wiring
Controller and soft starter
400V box with 32A circuit breaker and earth fault switch
230V input split and 32A circuit breaker with earth fault switch
Schematic

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