Hello all. We (or rather, the installation engineer) are having an unusual
problem during the initial charging phase of our newly arrived 500 (Oxford
long hold shielded magnet). At around the 20 amp level, the coil appears to
undergo a mini quench, whereby the current leaks away to a slightly lower
level (1/2-1 amp) over a few seconds, resulting in a steam train effect
through the helium vent hole, and after which the current creeps back up
again as the charge continues. This happened 3 or 4 times in a row before
the engineer halted proceedings and parked the magnet overnight at 15 amps.
Not much helium was lost overall. A more experienced engineer had never
seen this behaviour.
Does anyone have any insights into this behaviour and, more importantly, any
advice? Are they cryoshim quenches? In the factory, the magnet had quenched
at 80 amps before reaching field. Is this a clue?
__________________________________
Dr Iain B Cook
Anexus Laboratories Pty Ltd
A Member of ChemicalAnalysis
e-mail HYPERLINK
"mailto:icook_at_ChemicalAnalysis.com.au"icook_at_ChemicalAnalysis.com.au
web site HYPERLINK
"
http://www.chemicalanalysis.com.au/"www.chemicalanalysis.com.au
41 Greenaway Street
Bulleen Victoria Australia 3105
ABN 68005912612
Mob 0438 780 188
Ph (03) 9850 4708
Fax 613 9852 0772
(Home e-mail HYPERLINK "mailto:icook_at_bigpond.net.au"icook_at_bigpond.net.au)
___________________________________
The information contained in this e-mail message and any attachments is
confidential and intended only for the use of the individual or entity named
above.
If the receiver of this message is not the intended recipient, the receiver
is hereby notified that any dissemination, distribution, publication or
copying of this e-mail is strictly prohibited. If this e-mail is received
in error, please accept our apologies and notify the sender immediately by
return e-mail, and delete this message
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.755 / Virus Database: 505 - Release Date: 8/09/2004
Received on Thu Sep 16 2004 - 08:45:55 MST