I need to reduce a 400V 3P+N supply voltage as it can drift over the +10% limit, I don't particularly need to regulate it, just get it a bit lower.
Initially I though a double wound transformer close to 1:1 with a few tap links to let me select a lower output.
From a bit of searching I can see a lot of information on the use of autotransformers and buck-boost transformers in the US, but not much for the UK.
Is using auto/buck-boost acceptable for the UK or are there some fundamental reason not to do this? These transformers will be significantly cheaper and much smaller, which makes them appealing.
The rating would be around 100-120kVA
Thanks