sPHENIX discussion of the superconducting solenoid

["Mills, James A" <mills AT bnl.gov>]

Thanks Carl and Kin for coming in today to do the hi-pot.  Glad it went well, and it is now behind us.  Have a great weekend.

 

Thanks again guys,

Jim

 

 

 

From: sPHENIX-magnet-l <sphenix-magnet-l-bounces AT lists.bnl.gov> On Behalf Of Yip, Kin
Sent: Saturday, October 8, 2022 2:03 PM
To: sphenix-magnet-l AT lists.bnl.gov
Cc: Michnoff, Robert J <michnoff AT bnl.gov>; Kobasiuk, Frederick D <kobasiuk AT bnl.gov>; Karl, Robert F <rkarl AT bnl.gov>; Chan, David <dchan AT bnl.gov>
Subject: [Sphenix-magnet-l] Crash button connected ... hipot for the water-cooled-buses finally done !

 

Hello,

 

This morning, when Carl and I first came to 1008 before 11 am, we saw Mike Rau's electricians in 1008.  We discussed a bit and as Carl insisted, we waited for the electricians to have lunch before we did the hipot --- the "working around" principle.

 

In the meantime, Carl installed the 4 wires for the last Magnet crash button as I kept complaining and his tech hadn't done it after a month.   I was providing assistance like handing him the tools and throwing away his trashes 😬

 

Later on, we saw Rob Karl and Adrian (who was the guy that reconnected the MCM cables in 1008B yesterday and disconnected the braids ... so his name is not "Matt".  Sorry 🙁 ).  They told us they'd go to lunch at 12:30 pm so that we waited for them to go to lunch as well.

 

Carl probed around the Dump Resistor in 1008B.  As he seemed to remember exactly where he placed his probes to measure various resistances last time(s) and it took him 20 minutes or so to feel comfortable and finally set up the meter.  We measured the overall resistance of the water-cooled-buses to ground as ~10+ Mohm (compared to 1 Mohm on Wed. 🙂 ). 

 

Then, I drove back to 1008 Assembly Hall/IR to make sure that nobody was near the water-cooled-buses and then called Carl to start hipot.   The hipot took only like 5 minutes and went smoothly.  It seemed very clean (Carl's comment) and Carl could jump 50 V steps (instead of 5 V or something).   I attach Carl's measurements.  You can see that the leakage current increased linearly to about 50 micro-amp at 520 V (our hipot-voltage).   It's great that we've finally finished this hipot business which we originally planned to do on Wed. (a very rainy day).  Now, we understand how much the rain could lower the resistance to ground.

 

Joe Vasquez called me twice in the middle  and I've convinced him that we were not slowing down the electricians' work (apart from those few minutes' discussion) and Carl and I haven't left anything on the platform.   He may negotiate with Mike Rau and Rob Karl if any of their stuff are blocking the rack installation tomorrow.

 

I attach a picture of those shiny water connections (brass?!) near the water-cooled-buses and flags of Rob's and Adrian's.

 

So now, I can finally go to lunch ... thinking of Thai Food ... 😀

 

Kin