Hi Neil,

Sorry to hear that - it's so close to being finished.

On my machine I've re-drawn my circuit diagram to run the control side from 24V DC instead of 12V. I've ordered a 24V 5A SMPS and 2off 24V 4PDT DIN relays, laid out the 12V cooling pump and fan in series to give 24V load, and will drop a resistor (680ohm 1/2 Watt) onto the 12V LED line.
Click image for larger version.  Name: control_layout_24V_v6.JPG  Views: 500  Size: 108.0 KB  ID: 15314

Those are the easy bits. But can anyone out there help with the following? I'm missing the contactor to switch on the 70V linear power supply and 30V SMPS for the 4 drivers. This will connect after the 6A type D MCB. I keep reading around on this and am getting no-where. There are 2 problems:

One is that I can't find a simple way to work out the inrush current on the power supply so don't know the peak current rating for the contactor.

Second is that contactors appear to be rated for different applications, labelled AC1, AC2,AC3 .. .AC6a, AC6b . . . For example AC3 is for motors, AC6a is for transformers etc. I can't seem to find any that are 24V DC coil with AC6a rating. All are AC3 rating which is really for motors?

I noticed Dean posted a drawing in Neil's build log (e-stop circuit) with a 25A contactor so that is my starting point. Is this an AC3 unit? If so does this work OK with a high inductive load such as the transformer?

All real world experiences and advice welcome as the Chint 25A (NC1-2510Z) AC3 24V DC coil is about £50 when you add delivery and VAT.
http://chaloncomponents.co.uk/epages...0Contactors%22

Finally is it best to isolate both the L and N as I've drawn? I assume I should leave the earth permanently connected to the devices being switched i.e. not run earth through the contactor?

Thanks