Hello Folks:
We recently had our first magnet quench ever. Our old Bruker AC250
magnet (Oxford "Family" style narrow bore) had a soft quench.
We have replaced seals, pumped down, and cooled down. Everything so far
went according to plan.
A neighbor loaned us a Nicolet 70A power supply, which he had used many
times to energize Oxford magnets. However, our efforts today did not go
well. I'm left to believe that either the power supply is faulty or is
perhaps incompatible with this magnet.
The behavior that we observed was as follows:
According to the Nicolet manual, you are supposed to dial in your
desired current with the "current limit" potentiometer. The digital
panel meter, set to read the main current, initially reads the current
that you dial in with this potentiometer. Whe you turn on the main
heater, the panel meter should go to near zero and then begin ramping up
(if you're using the automatic mode). What we observed was that the
panel meter did not change at all. It stayed at the "set point"
current. Seems sort of like the superconducting switch never opens.
Switching the panel meter to read heater current reveals that we have
about 143ma when the heater is ON and zero when OFF, which sounds
reasonable and seems to indicate that we are actually passing current
through the heater.
We tried both the automatic and the manual (where you dial in a small
positive inductive voltage) procedures, and neither would work.
Any ideas, suggestions or words of magnet wisdom?
Does anyone have a Bruker BCN-70 (or BCN-100) we can borrow? (I'm more
familiar and comfortable with those.)
Thanks,
-Bill-
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Bill Gurley, Technical Director |
Department of Chemistry | Consider Linux and
Univ. of Tennessee, Knoxville | Open Source Software!
Received on Wed May 07 2003 - 17:42:09 MST