1. DSS Advisory Board 06.10.2003 Christoph Schäfer Rack Safety System

2. 2 Introduction The Rack Safety System is a proposal of CMS and was discussed during the September CMS week in detail. It does not replace the Rack Monitoring and Control System (RMCS), but it’s a complement and collects all directly safety relevant signals

3. 3 Philosophy Detector Level: DCS & DSS Rack Level: RCMS & RSS Split purely safety relevant information from monitoring & contol information

4. 4 reads out the ELMB’s two temperature sensors speed of tangential fans humidity sensor, etc. cuts power to rack(s) via software allows for trending and preventive maintenance Rack Monitoring & Control System The RMCS could be seamlessly integrated into the DCS Hardwired safety signals could be integrated into a Rack Safety System (RSS)

5. 5 Smoke Sensors (2 per rack, logical AND) installed by ST/MA (Centrale Incendie) Thermal Switch provide current loop Signal from the Detector Safety System (DSS) RSS stores the rack map RSS Inputs The RSS has to deal with 3 inputs/rack and should memorize all inputs

6. 6 cuts power to rack by sending first a signal to DCS in order to shut down power gracefully and after adjustable delay hardwired cut electronic equipment is best protected enables power to racks triggers fire extinguishing system foreseen for all UXC racks from the beginning RSS Actions The RSS has to trigger 2 actions/rack Flexible logic needed

7. 7 Each rack (320) and AC/DC converter (400) is controlled by a remotely controlled relay each relay can be opened/closed by a current loop provided by RSS RSS and all realys are in the service cavern ST/EL uses only RS485 to power on/off racks and AC/DC converters (granularity to be defined) Power Cut

8. 8 CMS uses exclusively the RSS current loop to switch on/off racks and AC/DC converters CMS has priority to keep rack or AC/DC converter off Power Cut

9. 9 Inside a rack there is no relay but a Power Distribution Chassis (PDC) A PDC comprises 5 manually resettable fuses: turbine 3 crates distribution box Power Cut

10. 10 Number of Channels 200 US racks 120 UX racks 400 UX ADC smoke detection 20012080 thermal switch 200120400 fire ext.none120? DSS403080 grand total: 2110

11. 11 All necessary functionality of RSS already incorporated in DSS Essentially no development for RSS needed ELMB card read out by the RMCS, no modification necessary RSS = DSS Clone

12. 12 Power Thermal Switch T TT T DSS RSS DCS E Fire Extinguisher EEE Smoke Sensor S Centrale Incendie SS SSSS DCS ELMB ST/EL

13. 13 Nitrogen extensive tests done at CERN by Reiner Schmidt and Stefano Fratianni positive results will be used as baseline solution for UXC racks Fire Extinguishing

14. 14 FM 200 gas special gas that reacts chemically with the combustion gases efficient Halon replacement no ODP and only low GWP tests planned with TIS this autumn Fire Extinguishing If positive result, preferred choice

15. 15 Fire Extinguishing Detection Line RSS N 2 or FM200 Gas Line

16. 16 Rack Monitoring & Control System use current ELMB cards, no modification Rack Safety System use existing DSS hardware, no development about 2000 channels Summary This CMS proposal covers:

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