Converting single-phase to three-phase for City & Guilds 2391 practical
L1 of the 230V source is connected to L1 of the 400V output. Therefore you will get 230V between L1 of the 400V output and the source neutral. Loads connected between L2 and L3 of the output and neutral will be supplied with 400V. I suspect that will prevent a proper test of the distribution board, but I know nothing of the board or the test.