Minutes of the 3rd North Area and Slow Extraction Interlocking Task Force

 

Present: Johannes Bernhard, Antoine Colinet, David Nisbet, Ivan Romera, Jan Uythoven, Thomas Zickler

Excused: Nikolaos Charitonidis, Verena Kain, James Ridewood, Francesco Maria Velotti

 

North Area Interlocking Task Force (I. Romera)

A new Beam Interlock System (BIS) will be deployed in LS3 following the consolidation of the North Area. The new BIS is designed to achieve the following objectives:

  1. Protect some of the North Area beam lines from receiving beam under unsafe conditions (EDMS 2435863).
  2. Protect the slow extraction and transfer line elements from themselves by either hardware errors or incorrect settings.
  3. Ensure that the slow extraction only takes place when FTARGET destination is set and all extraction elements have the correct settings.
  4. Allow all other destinations to continue unaffected (i.e. AWAKE, HIRADMAT, LHC, SPS_DUMP… should not be blocked if slow extraction is inhibited).

As stated at the first two meetings the use of the beam destination as main interlocking criteria to allow/inhibit the slow extraction is not reliable enough by itself and needs to be reinforced. The proposal is to complement the beam destination with the monitoring of the currents of the power converters involved in the slow extraction. Therefore, it is proposed to monitor the extraction sextupoles (LSE.10602, LSE.22402, LSE.40602, LSE.52402), the extraction bumpers (MPLH.21431, MPLH.21995, MPLH.22195, MPNH.21732, MPSH.21202, MPSV.21303, MPSV.21503, MPSV.22103, MPSV.22303), the magnetic septa (MSE.2183, MST.2177) and the TT20 main dipole string (MBE.2103).

D. Nisbet confirmed that all PCs powering the circuits mentioned above will be equipped with modern FGC controls in LS3.

The new interlocking criteria will take into account the following cases:

#for non-FTARGET beams
IF destination != FTARGET AND all extraction sextupole or bumper measured currents < Imin (+tol) THEN
        ALLOW circulating beam
ELSE
        DUMP circulating beam
 

#for FTARGET beams
IF destination == FTARGET AND all PC* measured currents are following reference function (± tol) AND all PC status == ON AND all PC not in simulation THEN
        ALLOW slow extraction
ELSE
        DUMP circulating beam

D. Nisbet noted that it seems feasible for TE-EPC to interlock the currents delivered by the power converters (either fixed threshold or reference function) depending on the beam destination. However, he noted that there is nothing at the moment that ensures that a reference function is not inadvertently changed and that this needs to be addressed together with BE-CSS and BE-OP.

The equations of the LSS3 Master BIC were reworked to include the monitoring of the power converter currents. It has to be noted that the proposed interlock matrix is a simplified version that does not take into account the position of the interlocked elements (e.g. the extraction sextupoles will have 4 inputs to the matrix, as they are located in 4 different locations of the ring). In addition, the inputs to the slave BICs were also revisited to accommodate the interlocks coming from the WIC and PCs in the TT20, TT21, TT22, TT24 and TT25 lines.

J. Bernhard requested to add switch buttons to interlock the beam arriving to some of the NA beam lines, in particular for the P42, K12 and M2 lines.

Next points to be followed up at the next meetings: