1. Failure mode impact studies and LV system commissioning tests
Technical review on UPS power distribution of the LHC Beam Dumping System
N.Magnin

2. Outline LBDS components - Powering summary LBDS diagnosis systems
Expected power failure impact
Commissioning tests
How to perform commissioning ?
When to perform commissioning ?

3. LBDS components Powering summary (1)

4. LBDS components Powering summary (2)
EN/EL circuit-breaker.
4x LBDS UPS-A circuit-breaker.
LBDS MAIN circuit-breaker.
LBDS UPS-B circuit-breaker.

5. LBDS diagnosis systems (1)
SCSS (WinCC):
Checks all redundant signals for presence (Triggers and Re-triggers).
Surveillance of Main and UPS power presence.

6. LBDS diagnosis systems (2)
TSU - FESA: Checks the status of internal TSU registers. (Detected clients, BRF presence, PLL locked, etc…)

7. LBDS diagnosis systems (3)
IPOC - TSU: Checks signals at input and output of TSU for presence and correct synchronisation.

8. LBDS diagnosis systems (4)
IPOC - MKD: Checks MKD current waveforms for correct strength and synchronisation.
Synchronous trigger
Asynchronous trigger (Switch erratic)

9. LBDS diagnosis systems (5)
XPOC:
BTVDD: Shows beam position on TDE.
BLMs: Show beam losses during extraction.
BPMD: Shows beam position in extraction line.

10. Expected power failure impact 1 - Main failure
Expected scenario:
LBDS MASTER PLC detects MAIN failure.
LBDS MASTER PLC issues an internal dump request to TSU cards.
Synchronous dump executed before MKD generator voltages reach their tracking limits (BETS/SCSS).
Expected result: Synchronous dump
Missing diagnosis systems :
NONE!
Assessment of correct LBDS behaviour: OK

11. Expected power failure impact 2 - UPS-A failure (a)
Expected scenario a):
LBDS MASTER PLC powers off.
Safety link to TSU is broken = TSU internal dump request.
Synchronous dump executed before MKD PTU and generator voltages reach their tracking limits.
Expected result: Synchronous dump
Missing diagnosis systems :
IPOC1-MKD
TSU-A registers
SCSS (WinCC)
Assessment of correct LBDS behaviour: OK

12. Expected power failure impact 2 - UPS-A failure (b)
Expected scenario b):
TSU-A powers off.
TSU-B detects TSU-A problem = TSU-B internal dump request.
Synchronous dump executed before MKD PTU and generator voltages reach their tracking limits.
Expected result: Synchronous dump
Missing diagnosis systems :
IPOC1-MKD
TSU-B registers
SCSS (WinCC)
Assessment of correct LBDS behaviour: OK

13. Expected power failure impact 2 - UPS-A failure (c)
Expected scenario c):
TSU-A detects power failure = TSU-A internal dump request.
Synchronous dump executed before MKD PTU and generator voltages reach their tracking limits.
Expected result: Synchronous dump
Missing diagnosis systems :
IPOC1-MKD.
TSU-A internal statuses.
SCSS (WinCC)
Assessment of correct LBDS behaviour: OK

14. Expected power failure impact 3 - UPS-B failure
Expected scenario:
TSU-B detects power failure = TSU-B internal dump request.
Synchronous dump executed.
Expected result: Synchronous dump
Missing diagnosis systems :
IPOC2-MKD.
TSU-B internal statuses.
Assessment of correct LBDS behaviour: OK

15. Expected power failure impact 4 - TOTAL failure
E xpected scenario:
TSU-A/B detects power failure = TSU internal dump request.
Synchronous dump executed before MKD PTU and generator voltages reach their tracking limits.
Expected result: Synchronous dump
Missing diagnosis systems :
ALL ! (But XPOC in REMOTE with BEAM)
Assessment of correct LBDS behaviour: BAD !

16. Expected power failure impact 5 - Shortcut in TSU crate (+12V)
Expected scenario:
TSU-A/B detects power failure = TSU internal dump request.
Synchronous dump executed.
Expected result: Synchronous dump
Missing diagnosis systems :
NONE
Assessment of correct LBDS behaviour: OK

17. Commissioning tests Tests already performed - Main failure
Tests performed locally at Point 6 in 2006.
LBDS-MAIN circuit-breaker has been opened manually.
Resulted in a synchronous dump.

18. Commissioning tests Tests already performed – UPS failure
Tests performed locally at Point 6 in 2006.
Four LBDS UPS circuit-breakers have been opened manually ‘at the same time’.
Resulted in a synchronous dump.
Is it representative of a real UPS failure ?

19. Commissioning tests Tests foreseen for end of LS1
MAIN failure:
Already done in 2006.
UPS-A failure:
Already done in 2006 (manually = not real UPS failure ?).
UPS-B failure:
Never done so far !
UPS-A + UPS-B failure
TOTAL failure (Main + UPS-A + UPS-B)

20. How to perform the commissioning LOCAL or REMOTE ?
LOCAL commissioning at Point 6:
REMOTE commissioning from CCC:
PROS:
Tests performed from 450 GeV to7 TeV.
Team on site in case of LBDS problem.
...
PROS:
Test with pilot beam at 450 GeV is possible.
Check LBDS with external diagnosis systems (XPOC).
Arming of LBDS is easy.
Could be done on a regular basis.
...
CONS:
We need to arm LBDS:
Close BIS loops.
Close LASS.
Arm BETS (connect BETS-Simulator).
Test with beam is not possible !
Cannot be done on regular basis.
...
CONS:
How to cut/re-establish power remotely ?
Tests at 7 TeV not possible.
Access needed in case of LBDS problem.
...

21. How to perform the commissioning Provoke TOTAL power failure ?
By-Pass mode for both UPS.
Opening of EN/EL Circuit-Breaker.
Is this possible in REMOTE mode ?
Impact of total power loss on other LHC equipment ?
(Cryogenics, QPS, Vacuum, BIS, …)

22. How to perform the commissioning Assess correct LBDS behaviour
We need the most important diagnosis FECs:
IPOC - TSU:
Check for correct TSU card behaviour.
Check LBDS synchronisation with beam.
IPOC - MKD:
Check for correct MKD strength.
Check for correct MKD synchronisation wrt each other.
We need power for at least these two important diagnosis FECs.
We need power for the network infrastructure.
Do we need a special power feed for diagnosis FECs & IT equipment ?
(At least in case TOTAL failure test is feasible)

23. How to perform the commissioning EN/EL modifications needed ?
Insert new circuit-breakers ? (Temporarily / Definitively ) ?
Remote control of circuit-breakers ?
Powering of diagnosis FECs from upstream of new circuit-breakers ? …

24. When to perform the commissioning
Must be done at the end of LS1 !
We will have all LOCAL conditions to arm LBDS.
Test procedure to be defined...
Should we do it on a regular basis ?
Should we do it at the end of every WS ??
LOCAL ? / REMOTE ?
Should we do it at the end of every TS ???
REMOTE ?