andré augustinus 9 october 2006 interlocks update

André Augustinus9 October 2006

Interlocks

update

9 October 2006ALICE DCS WorkshopAndré Augustinus

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


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


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



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



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?


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


Internal interlocksExamples

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)


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


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…


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

andré augustinus 9 october 2006 interlocks update

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