[Dsg-hallb_magnets] Solenoid Polarity Reversal

[Pablo Campero]

Hello Amrit, 

The test performed yesterday for the Solenoid MPS polarity reversal was to check if the MPS reacted as expected, which means after change the set-point for current in the MPS controls ('+' to '-' I_MPS values), verify if it was capable to automatically: 
1. Ramp down/up to 0 A 
2. Power off by itself 
3. Finally change its polarity. 

After set the current directly at -5 A (started at ''+'' current read-back), it was found that the QD #1 trips when MPS attempted to change polarity automatically from negative to positive and vice-versa. 

Agreed that procedure/ guidelines to change polarity in the MPS during ramp up/down of the magnet will be changed based on this final test. 

To both cases if is required go from positive to negative polarity or the opposite, to avoid trips (fast dump), first we have to go to 0 A manually (set 0 A in the MPS controls screen), turn off the power supply, wait for ~ 2- 5 min until we get 0 A, and then set positive or negative set points for the current. 

Best Regards, 
Pablo 



From: "Ruben Fair" <rfair at jlab.org> 
To: "Brian Eng" <beng at jlab.org> 
Cc: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Tuesday, September 26, 2017 4:45:20 PM 
Subject: Re: [Dsg-hallb_magnets] Solenoid Polarity Reversal 

Thank you Brian. 

I shall incorporate these guidelines into the ramp up/down procedure that I am presently modifying for the solenoid. 

Cheers 

Ruben 



From: "Brian Eng" <beng at jlab.org> 
To: "dsg-hallb magnets" <dsg-hallb_magnets at jlab.org> 
Sent: Tuesday, September 26, 2017 4:22:31 PM 
Subject: [Dsg-hallb_magnets] Solenoid Polarity Reversal 

Ruben, 

Attached are the timestamped notes that I took when Pablo and I were testing the solenoid earlier today in the window Bob had between CND installation. 

End result: if you wait long enough (I think at least 5 minutes should be okay [~2 minutes worked once, but tripped the other time]) after the MPS has ramped to "zero" and then turn the MPS off you can switch the polarity without any fast dumps. 

Also, unexpectedly, switching the polarity when the MPS is off will clear any QD faults remotely. 

-- 
Brian Eng 
Detector Support Group 
757-269-6018 


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