André Augustinus 9 October 2006 Interlocks update

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks  Already presented in last two workshops Recap of principles; latest news  Only covering so called hardwired interlocks Software “interlocks” can be implemented at several levels in PVSS, FSM etc.  External interlock signals from: gas systems and cooling plants  Internal interlocks to prevent damage to your detector

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks, Gas system  Gas systems The gas system of each detector will provide only one hardwired signal for that detector This signal is generated in the gas control PLC and will be a copy of the status of the gas system “OK” or “not OK” (contact closed / open) If requested this signal can be ‘delayed’ Dedicated timer hardware (commercially available) Contact will only open after a delay that can be set “by screwdriver” from 1 sec to several hours A prototype of this is currently being set up

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks, Cooling plant  As a minimum the cooling plant will deliver a single interlock signal to each detector So called detector interlock indicating if the plant is in “run” state A plant can move away from the run state because of a problem (alarm), or by operator command  The signal is generated by cooling plant PLC Closed when RUN, open otherwise  Nearly all plants are shared by several detectors The contacts are duplicated, one per detector

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks, Cooling plant  On request a few additional signals can be provided Based on the status of valve(s) in the input and return lines of each cooling circuit Will allow you to switch off (or keep off) power supplies for that cooling circuit Only requested by few detectors (e.g. SPD, SDD, TOF, HMPID)  There is no measurement of flow/pressure per individual circuit No possibility to provide signals based on this Would need significant modification of plant

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks, Cooling plant For information:  Each plant has an input to allow a detector to interlock (=stop) the cooling plant Do you see a use for this?  This only covers the 6 plants, for detector cooling and heat screens, delivered by TS/CV Not the PHOS crystal cooling plant Need to consider ‘internal’ interlocks Not the forced air cooling Started to discuss with ventilation people to see possibilities Request from muon; any other?

André Augustinus 9 October 2006ALICE DCS Workshop Interlocks  These interlocks only protect against malfunctioning of gas and cooling, not against problems “downstream”; on your detector  Ultimate solution: protect yourself by measuring where it could hurt  Several detectors integrated this principle in their design  Note that design and implementation of such protection (“internal interlocks”) is responsibility of the detector But, clearly, we can and will help you

André Augustinus 9 October 2006ALICE DCS Workshop Internal interlocks Examples  SPD Measures 120 temperatures on detector, through PLC based system Will switch off the corresponding power supply  TPC (and probably all ‘RCU based’ detectors) Temperature is monitored on FE electronics Power is switched off locally on the board (not on PS)

André Augustinus 9 October 2006ALICE DCS Workshop Other interlocks (detectors)  ZDC Will have a complex (PLC based) interlock system between the movement system and LHC (by TS/LEA)  PMD Position interlock (prevent switch-on when detector in ‘open’ position)  TPC fieldcage VHV Interlock system build-in in PLC based control system  Probably more where we are not aware of

André Augustinus 9 October 2006ALICE DCS Workshop Other “interlocks” (experiment)  You might be victim of many other “interlocks” Overtemperature or smoke in a rack will shut down your rack and equipment Flammable gas, smoke etc. in the area or in the experiment will shut down parts (most) of your equipment (safety action) Overtemperature or lack of cooling water will shut down several racks Pushing an “AUG” (emergency stop) or and “Equipment Stop” will switch off all or some equipment The occasional power cut…

André Augustinus 9 October 2006ALICE DCS Workshop Summary  Progressed on the inventory of existing (and requested) external and internal interlocks Presentation and (draft) document for TB  Remember interlocks are there to protect against fatal damage to your equipment and detector Is there to cover ‘exceptional cases’; the control system (DCS) will protect you adequately under normal circumstances  Contact us if you need advice in this field