sPHENIX discussion of the superconducting solenoid

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

Hi,

 

Carl and I went to measure the resistances for the 4 water-cooled-buses again this afternoon.  I attach the results in the picture.

4.x Mohm (of Return bus) yesterday  has changed to 75 Mohm !  The other Return bus is changed from 2.5 to 11 Mohm.

For the Supply buses, they are changed from 2 Mohm to 7 Mohm.

 

So, rains/humidity makes a big difference 😊  ( We have proven experimentally and scientifically. )

 

There was a small twist in the middle.  When we first measured the “Supply” buses, they were ~0.3 ohm => shorted.

We drove down to 1008-IR and asked the tech to move two 535 MCM cables slightly away from the platform metals --- they were

touching the metals 😊    After we returned to 1008B, we got the above measurements for the Supply buses.

 

When we were finishing, we met Adrian Steinhauff and we informed him of what we were doing to make him feel more comfortable (as

he’s curious).

 

Another breaking news :

When I got to my car, I saw Larry Vogt leaving with his van or truck.  I quickly ran to his vehicle and he told me that after the phases were reversed,

they can now turn on successfully.   But the pipe between 1008B and C were frozen somewhere so water can’t get to 1008B from 1008C.  

Plumbers are now fixing this problem … hopefully today.  

 

I guess we can’t complain that much as those pipes have been used since ~2016 or so.    I tell myself : “ What can be the next problem/obstable ?!”

☹ 😊

 

Kin

 

From: Yip, Kin
Sent: Wednesday, October 5, 2022 2:43 PM
To: Edward O'Brien <eobrien AT bnl.gov>; sphenix-magnet-l AT lists.bnl.gov
Cc: Michnoff, Robert J <michnoff AT bnl.gov>
Subject: RE: [Sphenix-magnet-l] water-cooled-bus to ground

 

Hi,

 

We were hoping >~ 50 MOhm so that the leakage current would be <~ 10 micro-amp (at ~520 V).   Now, it seems to be roughly ~500 micro-amp

(if we put in 520 V or so).

 

Kin

 

From: Edward O'Brien <eobrien AT bnl.gov>
Sent: Wednesday, October 5, 2022 2:40 PM
To: Yip, Kin <kinyip AT bnl.gov>; sphenix-magnet-l AT lists.bnl.gov
Cc: Michnoff, Robert J <michnoff AT bnl.gov>
Subject: Re: [Sphenix-magnet-l] water-cooled-bus to ground

 

    Hi Kin,
     Thanks for the update. By the way, what resistance
     were you expecting for the water cooled bus?

    Ed

On 10/5/22 2:04 PM, Yip, Kin wrote:

Hi,

 

The original plan was do a hipot for the water-cooled-buses.

This morning (around 11 am or so), Carl Schultheiss and Pablo Rosas found that there is about 1 Mohm resistance from the water-cooled-buses to ground.    To make sure that it’s the water-cooled-buses

but not our Dump Resistor, they disconnected the MCM cables from the Dump Resistor which took like an hour.  After that, they were able to measure that it’s “opened” to ground for the Dump Resistor but they

measured about 4 MOhm from one water-cooled-bus to ground and about 2 MOhm for 3 other water-cooled-buses.

 

Carl and Pablo are thinking whether we can live with these.  They’ll try to measure them again in a dry weather tomorrow.   There is a chance that they may want to disconnect the water-cooled-buses

at the West Wall to measure.

 

In the mean time,  Larry Vogt is circulating his water system without going to our sPHENIX Magnet Power Supply and the water-cooled-buses.  Pablo wants the water to circulate overnight before getting into

his Power Supply so that we will have cleaner water tomorrow morning (for the Power Supply).

 

Kin

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