Friday, April 29, 2016

Technical help question: Quantum Design magnet power supplies

I'd like to ask my readers that own Quantum Design PPMS or MPMS instruments for help regarding a technical glitch.  My aging PPMS superconducting magnet power supply (the kind QD calls the H-plate version) has developed a problem.  For high fields (say above 7 T) the power supply fails to properly put the magnet in persistent mode and throws up an error in the control software.  After talking with QD, it seems like options are limited.  They no longer service this model of power supply, and therefore one option would be to buy a new one.  However, I have a sense that other people have dealt with this issue before, and I would feel dumb buying a new supply if the answer was that this is a known issue involving a $ 0.30 diode or something.  Without a schematic it's difficult to do diagnostics ourselves.  Has anyone out there seen this issue and knows how to correct it?


Hura Hoas said...

I Dont have any answer

jim said...

Does the magnet have a sensor which connects to this power supply? I'm not familiar with this particular equipment, but I've experienced a similar problem due to a bad hall sensor on a large magnetic dipole. In my setup the ps adjusts itself according to the feedback it gets from a hall sensor, and if it is not well-positioned I cannot control the ps. Anyway, the problem is likely a sensor, relay or control cable which should all be easy to test. I've also had problems with Kepco ps shorting at high power.

Michael Susner said...

We had a similar problem when I was at Ohio State- we ended up having to replace our H-plate 3-4 times due to faulty field-effect transistors. Eventually we were forced to upgrade to the new model. At the time QD offered us a discount and we were able to do it for ~$6500. When the problem was intermittent, on the advice of QD we increased the heating time of the switch from 20-30 seconds (can do in the Model 6000 panel).