2 pole, 2 way switch question

[Chris Wilson]

I have 2 server power supplies, 50V at 73 amps each. Outputs are isolated from ground. I want to put them in a cabinet and have a high capacity switch to change their outputs from parallel to series. I want to use a 2 pole, 2 way switch for this, but suitable amperage ones are hard to find. The schematic I will work from is attached. Can I use this Ebay sourced switch, or even cheaper, use two double pole 100 amp mains isolation switches bought separately (for a lot less) with their toggles bridged together and mounted on a common DIN rail, with (and I think I would need to do this...) one mounted upside down??

http://www.ebay.ie/itm/CHANGEOVER-SWITCH-GENERATOR-TRANSFER-125-AMP-1-SINGLE-PHASE-DIN-RAIL-COSDIN-/281692272367?hash=item41962af6ef:g:0HwAAOSw9N1Vk9GR


Thanks!

[Ian.M]

No.  Its contacts almost certainly aren't designed to clear a 50VDC high current arc.

You need a switch  rated for at least 120V 100A DC  (120V because it has to clear the arc when the PSUs are in series)

Try googling: 100A DC knife switch DPDT

[Chris Wilson]

Ahh, OK, thanks, but would it be OK if no live switching was done? I cannot foresee a time when i would want to go from series to parallel or vice versa with the supply feeding a load.

[Ian.M]

Not OK, but it can carry the current and withstand the voltage.   If you are lucky, it might even survive operating under moderate load a few times.   However its an electrical fire waiting to happen unless you can rig an interlocked cover that shuts down the PSUs before anyone can access the switch.

[Chris Wilson]

OK, got you, thanks for the warning, I'll probably look for a knife switch, but only I will be operating it, and all the big knife switches seem to be in China, much appreciated Ian!

Actually they do an enclosed one, I could put a microswitch on the cover and have it run a relay on the input side, I have some BIG relays... Cheers.