Kin,
This is outside my expertise but, shouldn’t the cold hi-pot be done at the 4K where the coil will be run at the full current?
A short to ground during a quench at high current could damage the coil.
Is it worth saving a day off the schedule to risk damaging the coil (even if that risk is very small)?
Dave
From: sPHENIX-magnet-l [mailto:sphenix-magnet-l-bounces AT lists.bnl.gov]
On Behalf Of Kin Yip
Sent: Tuesday, January 02, 2018 10:33 AM
To: sphenix-magnet-l AT lists.bnl.gov
Cc: Sandberg, Jon N; Lenz, Michael D
Subject: [Sphenix-magnet-l] Hipot tomorrow ... Box installation (around the current leads) after that ...
Hi,
I've just talked with Carl on his cell phone and he's agreed to do the "cold" hipot tomorrow. So that Mike Lenz can start install
the barrier installation after that.
Carl also has one channel (voltage tap) that had a high offset, that needs to be investigated.
Kin
On 01/02/2018 10:21 AM, Kin Yip wrote:
Hi Joe,
You've missed the important point that Mike Lenz can only install the box/barrier around the current lead after you finish the hipot !!!!!
He can only start installing after you finish the hipot finally and reconnect the current leads with the cable. It'll take him a day or two to install.
Since you think it's OK to do it now, we should do it now.
Kin
On 01/02/2018 10:10 AM, Muratore, Joseph wrote:
Hi Kin –
Normally we would wait to hipot at the test temperature (4.5K) since the hipot of a magnet in He gas is problematic. We hipot in liquid He to avoid the problems with gas.
But since this magnet never touches He (conductive cooling, I believe), it should be OK. That being said, it takes maybe 10 min to do a hipot so you are not saving much time.
Joe
From: Yip, Kin
Sent: Tuesday, January 02, 2018 2:50 AM
To: Schultheiss, Carl
Cc: sphenix-magnet-l AT lists.bnl.gov; Muratore, Joseph; Sandberg, Jon N
Subject: RE: Can we do hipot at 90-100K ? ---- How about Jan. 3 ?
Hello Carl,
For the record, I’ve just attached another screenshot of the magnet temperatures (~102 K at this moment). You can see that the temperature should fall below 100K
sometime today.
We need to give time for Mike Lenz to install the box/barrier around the current leads (at the Valvebox). In order to install the box, we need to connect the current
leads with MCM cables. For that to happen, we need to finish the hipot.
Since the cool-down to 4K won’t happen this week, I hope to make use of the time a bit more productively. You don’t need to come in on Jan. 2, 2018. But
can you please come in on Jan. 3 (as you originally plan anyway) to do the hipot at 90-something K ? You have all the hours to do so as nothing else would happen
around the Magnet (while the Cryo group is working on the Plant).
Kin
From: Schultheiss, Carl
Sent: Monday, January 01, 2018 9:00 PM
To: Yip, Kin <kinyip AT bnl.gov>
Subject: RE: Can we do hipot at 90-100K ?
Hi,
We could but the time required to hi-pot is 2 to 3 hours; if nothing is wrong. I would like to wait until
the temperature is lower, especially since we had an unusual event.
Since the magnet is not cold I may not be in on Jan 2nd.
Good Luck
Carl
From: Kin Yip [kinyip AT bnl.gov]
Sent: Friday, December 29, 2017 4:46 PM
To: Schultheiss, Carl; Muratore, Joseph
Subject: Can we do hipot at 90-100K ?
Hi,
As you can see below that, next week, the Magnet temperature will probably be stuck at 90-100 K (LN2 temperature).
Can we do the hipot at 90-100 K ?? The contraction from 100K to 4K is <10% (of the entirety). This would save us a little bit of time.
Kin
-------- Forwarded Message --------
Hi,
Roberto reported (email below) about a false ODH alarm which closed the LN2 supply valve and cause other damages. The “vacuum skid”
didn’t concern us as we are not doing 2K Helium cool-down but only ~4K. I attach the temperature profile from a sensor at the
superconducting bus and you could see when this “accident” happened --- the warm of a few K.
In any case, the Cryo group has shut down the (He) plant whereas the LN2 continues to cool to LN2 temperature. They’re warming up the
Plant and hopefully, they’ll clear the “plug” (blockage) next week and cool-down the plant again. The original plan of going to cool from
~90/100 K to 4K on Jan. 2, 2017 will not happen. Since it’ll take a couple days to cool-down the plant itself, it’s not very likely we’ll see
4K next week.
I wonder whether we can do the “hipot” at ~90/100 K or so as there isn’t much contraction between 100K and 4 K anyway.
I also talked with Jonathan Reich and actually told what phone to “catch” Roberto. There were actually two alarms. He’s already replaced
the sensor in the “compressor room” which has nothing to do with the LN2 valve closing. He’ll try to see whether he can replace the other
ODH alarm in 912 (which has been giving a lot of false alarms) next week while we’re still having cryo operation in 912.
Kin
From: Than, Yatming (Roberto)
Sent: Friday, December 29, 2017 12:27 PM
To: Yip, Kin
Cc: Orfin, Paul; Tuozzolo, Joseph E; Tallerico, Thomas N; Masi Jr, Leonard; Warkentien, Andreas F; Sardzinski, Mark A; Lederle, Dewey L; Talty, Patrick; Van Kuik, Brian; Soria, Victor
Subject: ODH ALARM 912
Kin,
We had an ODH alarm event in 912 around overnight.
Shutdown the LN2 supply valve [automatic] into the bldg. to cryo plant and sPHENIX LN2 cooler.
The fans kicked on in the compressor room and temperature dropped sufficient and the water lines in the compressor room and water/oil heatexchangers on the vacuum skid cracked. The water tower eventually tripped on low water since the water
was not returning to the tower.
Sullair helium compressor for the cryoplant tripped.
System is restarted but the cryoplant is not performing.
I have inlet pressure but the cold end of the plant and expander have to high inlet pressure.
Appears I have plug in the plant.
So shut down plant.
We have next week to get the plant back up.
Roberto
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