Soft Start Advice

[cropwell]

Now, after a little bit of digging around t'Interweb, I realise the problem- it's big toroidal transformers needing a high-current fix at switch on. As I haven't used a toroid for anything other than power supplies for pre-amps and mixers I have not had a problem like that to solve. I must pull the case off one of my 1KW PA amps to see what that uses to switch on the power to the toroid in it.

Never got round to that Laplace stuff at Uni, it was over 50 years ago and I studied Geomorphology

[m_c]

A contributing issue is CNC power supplies have a nice big capacitor to charge from nothing at switch on, which contributes quite heavily to the surge.
Placing a resistor inline, limits the surge until everything reaches working voltage.