sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hi Carl,

I just chatted with Don Bruno and I remember the hipot test that we did 
in early 2018 for the high-field test.

When SMD techs did the hipot test, the voltage ramped continuously at 
first at 3V/second and was later changed to probably 1.5V/second or so.


But when I talked with Don, Don told me that you guys usually ramp it up 
slowly by hand, and you'd stop at each step to allow the leak current to 
be steady before you ramp up again.   I think it was like that too when 
we did the hipot test in 2018.

But this was not the case when we did the hipot test last Thursday.  
Because their "automatic" program just kept rising constantly (at 3V/s 
or 1.5V/s without waiting for a steady leak current) until it failed and 
went beyond 10 micro-Amp or suffered an "arc failure".  [ In any case, 
-Lead is better than +Lead. ]

Maybe, if we do the hipot more slowly, the hipot could succeed. Don told 
me that it should be "DC", not "AC".  { During nominal ramping for the 
sPHENIX Magnet, the voltage is low, like 10-20 V or something like that. }


This "slow" scheme could result in the same failure but may be not ?! 
It's worthwhile trying.

You are the expert :-)   It's just a thought ...

Kin