Last Updated on Thursday, January 13, 2005 at 12:34:36. by Author: Don Barton

Magnet, General Information/Help

(Expert)

MCR IS NOW RUNNING THE MAGNET
(as of PR04)

Contents

WHAT YOU NEED TO KNOW ABOUT MCR CONTROL

MCR will control polarity and normal ramping of the magnet through their ramp sequencer.  The sequencer will determine the "polarity" for a store by retrieving the choice set via the MCR Experiment Info Exchange window [BERT] that runs on Phuscia.  The choice for a store must be set during the previous store (at store energy or during the ramp down).

During routine running MCR is responsible for responding to faults/trips of the magnet.  If, however, the fault occurs during collisions and several minutes go by without apparent action, don't hesitate to call MCR to discuss the situation.

PHOBOS remains responsible for carrying out an emergency shutdown in case of fire, as long as PHOBOS is on shift.  MCR must be notified if PHOBOS is not to be manned and the PHOBOS key inserted in PS [for MCR's convenience].

 

Quick Guide to Magnet Ramp Down

Ramp down before beam injection (start of Store) and before extraction (end of Store):

For more detailed instructions see specific items in Contents.   In Magnet window on RHIC X-term:

  1. Click on Zero.
  2. Confirm that Silicon Bias is OFF. 
  3. Click on Ramp
  4. Click on Standby when ramped to Zero.

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If the Magnet Trips or Refuses to Ramp...

If the PS has suddenly gone to Standby or Standby-Fault from On and/or the magnet current does not follow the reference, do the following:

  1. If the magnet reference is still ramping (the actual current will be zero), click Stop Ramp. 
  2. Click Zero for Desired Magnetic Field.
  3. Click Ramp, to return the reference to zero.
  4. Click Standby which will attempt to clear fault (which sometimes are transient).
  5. Attempt to Ramp Up again
  6. Record in log the last few messages at bottom of Magnet window and the contents of any error pop-ups.
  7. Quit program and restart, then try again.
  8. If unsuccessful, call CAS.

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Magnet System Description

The Phobos Magnet System consists of the magnet inside the experimental interaction region and the magnet power supply and cooling system in the utility building (1010A). The magnet monitoring happens in two different places: the magnet power supply is monitored through RHIC controls, the magnetic field and the magnet cooling water temperature is read out through a DVM in the electronics room (above cabinet #2). The magnet power supply is controlled through a special program on the RHIC X-term. The nominal magnet states are Standby & On when there are full time shifts and Off when there are no shifts.

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The Magnet Control Page

You control the setting of the magnet from a special PHOBOS magnet control program (emc). This page is accessible from the RHIC X-terminal ('acnxtek79').  During normal running the 'Magnet' program should be running iconified except when needed.  Double-click icon to open window.  Please do not start duplicates!  If it is not running, you can start the magnet program by clicking somewhere in the root window ('the background' in the X-terminal), holding the mouse button and selecting 'Magnet Control (emc)' page in the 'Phobos Controls Console' drop-down menu. You will be asked for a password, which is listed with other PHOBOS passwords.  You should see something similar to the following picture:

Command buttons are colored with inactive buttons grayed out.  In the example shown, the magnet is OFF and the only allowed command is Standby.  You may also Ramp the reference to Zero (useful after a fault).  Fields with a white background contain displays of actual states of the power supply and and measured reference (DAC output) and current.  The bottom message area contains historical comments on actions and results [a timestamp will be included soon].

The  Emergency OFF button is only to be used in the case of a major emergency like fire in the tunnel or service building.  It will request you to Confirm or Cancel this request.  On confirmation, the magnet will be crashed to the Off state and the reference will be returned to Zero.

By right-clicking on any field title, you will activate a help window for that field that contains useful information.

If the interface Readback Mode is not set to A, you will see a pop-up asking if you want to change it to A.  Reply Yes during normal operation.  If CAS is working on magnet PS it may need to be B, so reply No.  In that case displayed plot parameters will not be the expected readbacks, but other program features will operate correctly.

If the power supply is in 'Local' mode (CAS can put it there with a switch on the power supply), the interface buttons will be disabled and a message will appear at the bottom of the screen.  Go to the PS and switch the switch on the left hand side from 'Local' to 'Remote' if it is.

You can Print the program window from the File menu.  The Diagnostics menu has the following entries:

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Bringing the Magnet from Off to Standby

Steps 1-6 may be carried out with RHIC in any state.  

If you have problems at any stage, please right-click for help or have a look at Troubleshooting.

If the magnet state is Off:

  1. Sweep the area, making sure that all magnetic materials that do not belong in the area (tools, screws etc.) are put outside the 5-Gauss line (the red line on the floor). All people in the vicinity of the magnet should be notified of the intent to energize the magnet.
  2. The Operations Manager should have been notified that the magnet is about to be energized. The Shift Leader should open the 'Phobos Magnet Key'-box on the left hand side of the door in the electronics room. Take the key out.  
  3. Make sure Actual PS State on the control page is Off.
  4. The 'Phobos Magnet Key' should be inserted in the side of the Power Supply. 
  5. Click on Standby.  The Actual PS State should say Standby after this. If errors or faults are indicated, click Standby again to attempt to clear faults (a few times with a few-second wait).  If this does not work, call MCR and ask for help from CAS.

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Ramping the Magnet Up

The magnet may not be turned On and ramped without MCR permission, which will be given at 'Store' and during suitable down-times.

  1. If RHIC is operational, ask MCR at x4662 for permission to turn on the Phobos Magnet.  
  2. Notify  Cryo Main Control at x3837 that you are about to turn on the Phobos Magnet. The magnet lowers the line voltage on rampup and cryo sees their UPSes firing.
  3. Verify that the Desired Magnetic Field and Actual Field are Zero.  If not, click Zero for Desired Magnetic Field, then click Ramp.
  4. Click On for Desired State.  A pop-up with the following instructions will appear:  
  5. Wait 20-30s. Go to the Power Supply in the Utility building and verify that the voltage on the 'Output Regulator Monitor' is about -1.5V (negative 1.5V). If it is a positive voltage DO NOT turn the magnet on, but call the CAS watch and tell them to come out. Failure to act on this can result in having the magnet 'take off' in an uncontrolled way and potentially damaging the experiment.
  6. Confirm or Cancel  as appropriate.  If confirmed, the Actual State should change to On and a pop-up will show In process... during a warm-up period of 30 s.  If this isn't the case, click Standby and retry steps 3-6.  If no success, call CAS.
  7. Click on Full for the Desired Magnetic Field.  Then click on Ramp.
  8. A pop-up will appear to warn that the PHOBOS Silicon should be OFF (this means Bias Off).   If Silicon bias is Off, click Confirm to ramp; Cancel otherwise.
  9. The ramp to full field will take more than 2 minutes.  A progress bar will be displayed and the reference (DAC) and measured current values will be plotted.
  10. If plotted current value goes to zero and/or magnet trips while the ramp continues...
  11. After ramping, the program checks the current to see if it roughly corresponds to the desired level.  If the test fails it pops a message saying to call CAS and the Actual Field will show Error.  Look at the plotted current on the graph and check the value reported on the pet page accessible via the diagnostics menu.  [There is a known intermittent failure of the readback being looked at by the Controls group, which can cause gaps in the plot] If measured current matches the reference and agrees with where you want it, it's ok.  Otherwise call CAS.

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Ramping the Magnet Down

  1. Click on Zero for Desired Magnetic Field. 
  2. Click on Ramp
  3. A pop-up will appear to warn that the PHOBOS Silicon should be OFF.   Confirm to ramp; Cancel otherwise.
  4. The ramp down will take more than 2 minutes.  A progress bar will be displayed and the reference (DAC) and measured current values will be plotted.
  5. Click on Standby when ramp-down is complete and Actual Field shows Zero.

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Changing the Magnet Polarity

The polarity can only be changed with the Magnet in Standby.  If there is current in the magnet, ramp the magnet down first.

  1. Click on the button for the other polarity (it should be the only one enabled).
  2. The motorized reversing switch will take about 10 seconds to operate, during which you will see an In process... status.
  3. If this maneuver ends with a fault indication, call CAS.

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Turning the Magnet Off

  1. Click Off for Desired State.  Actual State should change to Off.
  2. If the shut-down will be long OR if there will be work done in the near vicinity of the magnet you MUST take-out the interlock key. It it the key labeled 'Phobos Magnet Key' on the side of the Power Supply. Take this key out and place it back in the 'Phobos Magnet Key Switch Box' in the electronics room.
  3. Notify the Operations Manager of the status of the magnet.

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Troubleshooting

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Who & Where is CAS?

The Collider-Accelerator Support (CAS) watch (24/7 coverage during operation) can be reached by calling MCR at x4662 and asking for them to contact CAS for us.

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Checklist Instructions

1. Go to the RHIC X-term and find the 'Magnet Control' window. Click on 'Diagnostics', then 'Check Readback Mode'. You will see a message at the bottom of the window giving the Readback Mode.  If it is 'A', no action is required.  If it is 'B', a pop-up will also appear asking if you want to change it to 'A'.  Reply 'Yes' during normal operation.  If CAS is working on magnet PS it may need to be 'B', so reply 'No'. 

2. Go to the 'MAGMON' computer. You should see the following arrow in the top of the 'MonitorMagnet.vi' window, just below the menu (the line with 'File', 'Edit' etc)

if you see this arrow:

then the VI (virtual instrument - the 'graphical script' of labview) is not  running and you will need to click on it  to activate it. If the VI is not running at all (you don't see any window with 'MobitorMagnet.vi'), you will need to start it by double clicking on the 'Magnet Monitoring' Icon on the 'Desktop' of the 'MAGMON' computer. 

3. Look at the 'StatusStringM' field on the VI. If it says 'Off', then you can safely ignore any Error messages such as 'Fault' etc. 

4. Look at the 'Measured I' and 'Measured V' fields, they should show fluctuating values. If the magnet is off, then the values fluctuate around 0, otherwise they fluctuate around the magnet set point. If these fields show 0 exactly, then the magnet monitor lost contact with the CDEV server (such as when the server was reset). You will need to exit labview and restart the magnet monitoring by clicking on the 'Magnet Monitoring' Icon on the 'Desktop' of the 'MAGMON' computer.

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Please send all comments and suggestions regarding this page to Don Barton.