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Hardware Temperature Interlock Preliminary Ideas Nick George – Rick Van Berg. The Challenge. Incident in SR Review, 7/6/6
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Hardware Temperature InterlockPreliminary IdeasNick George – Rick Van Berg R. Van Berg, July, 2006
The Challenge • Incident in SR Review, 7/6/6 • “The TRT subdetector should study the possibility of an HW interlock scheme (and implement it), in order to avoid overheating of detector elements, possibly using the same tools as the silicon detectors.” • “Any abnormal and potentially dangerous situation caused by the malfunction of a service should, as much as possible, at either DSS or hardware interlock level be detected by an independent sensor directly measuring the result of this service …” R. Van Berg, July, 2006
ATLAS Safety Scheme • DCS – control, monitor, operate normally • Flexible; Many Options; Complex Code • DSS – ATLAS wide • Inflexible; Few Options; Simple Code • e.g. drop rack power in 5 mins. if no cooling • HW Interlock – local last resort • Fixed; No (?) Options; HW only, no code • e.g. kill bulk if over temp R. Van Berg, July, 2006
TRT Reality • Barrel is constructed • EC C is essentially finished • Type II cabling is defined and is being installed • Type III cabling is defined and is being installed R. Van Berg, July, 2006
Independent temp sensors on boards Independent readout Independent cable plant from ID to power racks NTC thermistors on each board STP from NTC to PP2 ELMB readoutDCS No (well almost) extra wires from ID out What we would like vs. what we have R. Van Berg, July, 2006
Basic Scheme • Use present thermistors on boards but duplicate connections – possible because TTC PP needed a small redesign for a reset signal - add a connector to bring out all NTC signals to “somewhere nearby” • Sense high temperatures “nearby” • Send simple alarm signal to power racks to shut off Weiner bulk supplies on high temp. R. Van Berg, July, 2006
PP Schematic – 20 NTC per PP +2.5V Ref NTC Thermistor ELMB 470kW New PP Connector 47kW @25C FE Harness PP GND Patch Panel R. Van Berg, July, 2006
“Nearby Box” Comparator NTC Input Alarm 50 mV Ref R. Van Berg, July, 2006
What “Alarm” - Barrel • Power Feed by 1/32nd • 1 Cable per triangle • Data Cabling by 1/32nd • 1 (2) NTC Thermistor per triangle • Cooling by 1/32nd • 1 Loop per Module • Alarm could have 2 or more • NTC per cooling loop R. Van Berg, July, 2006
What ‘Alarm” – End Cap • Power Feed by 1/32nd • 1 Cable per triplet (almost…) • Data Cabling by 1/32nd • 1 NTC Thermistor per triplet • Cooling by half wheel • 2 Loops per Wheel • Alarm could have only 1 • NTC per cooling loop per 32nd R. Van Berg, July, 2006
Alarm Condition? • One NTC over temp per cooling loop • All NTC over temp per cooling loop • More than one NTC over temp per cooling loop? • N/M NTCs over temp per cooling loop Note that some boards do not have good NTCs – not checked in board testing R. Van Berg, July, 2006
Power Supplies • DCS controls PP regulators and Bulk settings – 1/32 x 1/32 • DSS could control rack power for Bulk – many 32nds (see next slide) • HW Interlock should?? • AC mains (rack power) • Bulk chassis interlock • Something else R. Van Berg, July, 2006
3 2 4 1 5 & 6 5 8 3 1 Rack – 4 bulks, 13 PP 1 Rack – 4 bulks, 12 PP R. Van Berg, July, 2006
Finer Information Logic 8R 8 Bit Diff ADC i 4R 2R 1R Nearby PP USA15 orPower Rack R. Van Berg, July, 2006
Prototype R. Van Berg, July, 2006
Numerology • Per Patch Panel • 1 TTC for EC – 20 NTC sensors • 1 TTC for Barrel – 8 NTC Sensors • Patch Panels mounted in groups of 3, 5 & 8 • CAN bus cables (9 pair) • Installed 1 per PP • Need 1 per PP group • 2(?) or 4 or 7 “spare” cables per platform R. Van Berg, July, 2006
Propose • Build a comparator board capable of handling 3 PP (6 TTC cable inputs - 28 sensors per PP) • Group 28 NTC thermistors in fours - encode • Send 7 encoded signals per PP to power racks • Figure out the Alarm logic later… R. Van Berg, July, 2006