hardware temperature interlock preliminary ideas nick george – rick van berg

R. Van Berg, July, 2006 1

ATLAS TRT

Hardware Temperature Interlock

Preliminary Ideas

Nick George – Rick Van Berg


ATLAS TRT

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 …”


ATLAS TRT

ATLAS Safety Scheme

1. DCS – control, monitor, operate normally• Flexible; Many Options; Complex Code

2. DSS – ATLAS wide • Inflexible; Few Options; Simple Code• e.g. drop rack power in 5 mins. if no cooling

3. HW Interlock – local last resort • Fixed; No (?) Options; HW only, no code• e.g. kill bulk if over temp


ATLAS TRT

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


ATLAS TRT

What we would like vs. what we have

• 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


ATLAS TRT

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.


ATLAS TRT

ELMB

+2.5V Ref

PP GND

NTC

Thermistor

FE Harness

Patch Panel

47k

@25C

470k

New PP

Connector

PP Schematic – 20 NTC per PP


ATLAS TRT

“Nearby Box”

NTC Input

50 mV Ref

Comparator

Alarm


ATLAS TRT

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


ATLAS TRT

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


ATLAS TRT

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 loopNote that some boards do not have good NTCs – not

checked in board testing


ATLAS TRT

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


ATLAS TRT

1

23

4

5 & 6

1 Rack – 4 bulks, 13 PP

5

8

3

1 Rack – 4 bulks, 12 PP


ATLAS TRT

Finer Information

4R

2R

1R

8R

Nearby PP USA15 orPower Rack

8 Bit Diff ADC

Logic

i


ATLAS TRT

Prototype


ATLAS TRT

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


ATLAS TRT

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…

hardware temperature interlock preliminary ideas nick george – rick van berg

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