sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Hi,

 

I hope everybody can set it as the highest priority as I am.   But people in SMD have other priorities such as their AUP testing.

 

Anyway,  John Haggerty and I, and later on Paul Orfin, took a look at the Valvebox between 10:15 to 11:20 am or so … John was looking,

taking pictures and discussing all the possibilities  … and Paul described what they did etc.   Tomorrow morning, I’ll find Carl in his

office at 8:30 am and then we’ll get all the “electrical” equipment to do more serious detective probing and measuring with the Valvebox.

 

At the moment, or this morning when we were there,  Fluke showed “max. resistance” (overloaded) when we measured the resistance between the +Lead and ground.

We certainly needed higher voltage (than 9V in Fluke) to show the problem consistently.   ( On Thursday, Hipot tests all failed each time we thought we

solved the problem when the Fluke meter showed “max. resistance” in resistance measurement. )

 

I’ll meet with Piyush Joshi at 3:30 pm outside Ann Marie’s office so that he can sign a paper for escort/TLD etc.  (such that I can escort him in 912).

 

Kin

 

From: Edward O'Brien <eobrien AT bnl.gov>
Sent: Monday, April 4, 2022 10:16 AM
To: Yip, Kin <kinyip AT bnl.gov>; sphenix-magnet-l AT lists.bnl.gov
Cc: Galioto, Peter <pgalioto AT bnl.gov>; Riker, Kenneth D <kenr AT bnl.gov>; Sullivan, Daniel <dans AT bnl.gov>
Subject: Re: [Sphenix-magnet-l] Problem +ve Lead fails hipot ---- crisis ...

 

    Hi Kin,
     OK. I am confident that the combination of the CAD and SMD
    team can fix this. However we should try to get this resolved
    as soon as possible. Please make the investigation of
    this high priority. Thanks.

    Ed

On 3/31/22 4:33 PM, Yip, Kin wrote:

Hi,

 

This morning, after we filled out a few forms so that I get a red TLD can escort Dan Sullivan and Peter Galioto to Bldg. 912 to do a hipot.

 

Long story short, the -ve Current Lead (B) seems to pass the hipot with flying color, nominally 0 micro-amp (the testing report says: max. ~0.3 micro-amp).

The hipot was done at 520 V.

 

But the +Current Lead (A) failed.  We set it at 10 micro-amp  but it failed immediately, or quickly at 20 V, 50 V or 70 V … (even a very slow rate … 300 s for 0 to 520 V).

Even with a Fluke meter, we sometimes measured 60-80 kOhm (between lead and ground) in the morning but sometimes, it’s

“open” (maximum resistance of that meter).   Dan and Peter tried  to poke around and took off the heater on the +ve lead … and looked at those wires underneath

the chimney.

 

Ken Riker and Dan Martin had some ideas and they re-wrapped the MLI (around the ceramic break or so) around noon.

 

At 1:30 pm, we tried again.  The Fluke meter said that the resistance is maximum (open) between +lead and ground  but the hipot failed again.  We tried to

separate those wires hanging from the chimney again and tried again.  The last time, it went to 90 V and had an “arc failure”.

 

Then, we measured it again and we saw “10 kOhm” . ….  Half an hour later when Ken Riker and his colleagues tried to measure again, the resistance was “OPEN” again.

Something was “intermediate” ….coming and going …

 

I talked to Carl and Carl talked with us (Piyush, Dan and myself).   There is no obvious solution.   Carl will come to take a look next week.

 

Piyush said he might have time to take a look at 11 am tomorrow.

 

Let me be dramatic … this is sort of a crisis.   Without solving this problem, we don’t have a magnet ☹

 

Kin

 

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