sPHENIX discussion of the superconducting solenoid

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

Hello,

 

I had to wait for CAS to close the contactor in the dump resistor before I could start to ramp the magnet current up, which was about 22:50 on Friday.

 

But after I turned the power supply on from standby, it went to “on” for a few seconds and then went to “standby”.

I saw the interlock of “soft start did not open” turning red.  I tried another time and it was the same. 

 

I called Pablo (who happened to come to BNL for AGS magnet) and he told me to try again but the result was the same.   He then agreed to get

CAS to go with him to 1008B mezzanine to perhaps to take a look.   But after hanging up the phone, I tried again and this time, I went to

“off” and I saw more interlocks turning red.  I then went to “standby” (which cleared all the “red” interlocks --- normal behavior) and then

I tried to go to “ON”.  Ahaha … this time, it stayed “ON”.  I immediately found Pablo in their CAS office and he said that it’s OK to ramp it on.

 

I then started to ramp the magnet (after calling MCR/1008/Cryo).  But at about 550 V or so, I was “standby” again and it suddenly tripped (23:04) !! 

I called Cryo who claimed innocence.   But then CAS called me and I then realized that they were in 1008B mezzanine with Pablo !  I thought Pablo

had gone home.

 

It took me and CAS a few minutes to reset everything.  And then we started ramping again as Pablo encouraged me to.  I then asked Pablo whether he

had any clue why it tripped.   Pablo said that it might be due to them trying to investigate in front of the power supply and touching the PLC etc.  He said

that they were leaving and wouldn’t touch anything any more 😊

 

So, finally, the ramp started from about 23:29 and ended at about 01:17 .   

 

Honestly, I sense some instabilities in the power supply.  Hopefully, it’s just a fluke.    I certainly don’t enjoy all these power dips !!! 😥

 

Kin

 

From: Yip, Kin
Sent: Friday, May 31, 2024 7:40 PM
To: sphenix-magnet-l AT lists.bnl.gov
Subject: What are you doing at 18:37 ? .... pictures for Carl/Pablo to look

 

Hello,

 

Why am I at the Lab. Friday after 6:30 pm ?

 

Well, partly because I have nothing else to do and partly maybe I have a hunch for what was going to happen …

 

At about 18:37, there was a power dip which brought down our beloved sPHENIX Magnet (fast discharge) and RHIC yellow/blue beams,

as well as STAR magnet, AGS MMPS, Booster, AGS, Linac RF ….

 

So, I came up to 1008B mezzanine and took a picture of the power supply PLC interlock history (nothing inspiring) and the quench detector/Labview program.

On the quench detector/Labview, it’s the classical “coil difference” that caused the quench interlock.  

 

I’ve restarted the Labview program and reset everything that I can reset in the PLC and pet.  Writing to here, I actually just remember to

reset the currents to 0 in the ramp page.  Otherwise, it’ll complain when we try to ramp 😊   As experienced I’m now 😅

 

Before we can attempt to ramp the magnet back, we need to Cryo to clear the Cryo interlock and Cryo permissive which would take a few hours.   When

that’s ready, I’ll ask CAS to press the contactor at the dump resistor.   I talked to the CAS staff today who knows which button to press.

 

 

Carl and Pablo, I’ve attached the pictures of the PLC interlock history as well as the Labview display before I restarted the quench program.

I also attached the plot of magnet currents at the time of fast-discharge.   You may investigate more … Let me know if there is something
more than power dip causing the fast-discharge. 

 

 

Kin

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