P10- Why is there a difference between voltage output setting and voltage output on the status screen?

I´m wondering why there is a difference between the Voltage Output in the settings and the status screen voltage output on my P10. Shouldn´t the status screen show the same voltage as defined in the setup?

In my case I want an output of 230V. To achieve this voltage on the status screen the setup voltage has to be set to 233V. In my case, this is also regardless from the settings High Regulation / low distortion.

Thank you for your explanation.
Regards Stephan