hyper status and preliminary testing of the new hyper bus fault detector cp work done by cp section...
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Status and Preliminary Testing of
the New HyperHyperBus Fault Detector
Work done by CPCP section 10-12.2008Based on Slides from Knud DAHLERUP-PETERSEN
Architectural Design by Reiner DENZAnalysis by Zinur CHARIFOULLINE
❖Preliminary Bus Splice Quality Characterization ( Nano Ohm Meter Function)❖ Voltage Signal Noise Reduction Integration Hierarchy
❖ Differential Analog Bandwidth: 0-200 Hz (tested at 1 kHz)❖ 24bit ∑∆ ADC (modulator frequency: 32768 Hz)❖ Hardware (in QPS) 24bit ∑∆ ADC integration period: 187 mS (5.35 Hz)❖ Firmware (in QPS) moving rectangular integration: 18.9 S (101 samples)❖ Software (in CCC) DC integration time: typically > 10 minutes (this is what counts!)
❖ Feasibility of nΩ Resolution ?
❖Real Time Early Warning Bus Fault Detection
❖ Bus Inductance Compensation (94 µH)
❖ Feasibility of 300 µV Threshold ?
Both functional aspects of the new bus fault detector have
been tested:
Results from Measurements Performed on 27 Oct. at up to 1250 ADCDQQDC Detector Card now linked up to the WorldFip and LHC Logging
Strong Filtering, Sampling Time 187 ms, 100 points Sliding AveragePost Treatment of Data with Labview
380 µV1250 A1 hour
Results from Measurements Performed on 27 Oct. at 1250 ADC
Results from Ramping, Flat-Top and Ramp-down
±10 µV
Real Time Noise Floor
Results from Measurements Performed on 27 Oct. at 1250 ADCwith DQQDC Detector
100 nV100 nV
490 ± 90 pΩ
490 ± 90 pΩ
245 ± 45 pΩ / Splice245 ± 45 pΩ / Splice
Zero Closure = 20 nV
~ 1 hour integration / point~ 1 hour integration / point
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Bus VoltageBus Voltage
Selected DC DataSelected DC Data
50 µV50 µV
375 µV375 µV
4 A/s4 A/s
1 hour1 hour94 µH94 µH
3500 Amp Ramp3500 Amp Ramp 29 October
Results from Measurements Performed on 29 Oct. at 3500 ADCwith DQQDC Detector
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290 ± 50 pΩ / Splice290 ± 50 pΩ / Splice
200 nV200 nV
580 ± 100 pΩ
580 ± 100 pΩ
Zero Closure = 50 nV
10 min - 1 hour integration / point10 min - 1 hour integration / point
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500 nV500 nV
650 ± 29 pΩ
650 ± 29 pΩ
Results from Measurements Performed on 30 Oct. at 5000 ADCwith DQQDC Detector
325 ± 15 pΩ / Splice325 ± 15 pΩ / Splice
Zero Closure = 50 nV
Ramp [Amp] Resistance/Splice [pΩ] estimated statistical error [pΩ]
1250 245 45
3500 290 50
5000 325 15
mean 287 28
Repeatability & ConsistencyRepeatability & ConsistencySame Splice
Different RampsDifferent Days
Can we measure better than 1 nΩ ?
YES WE CAN !YES WE CAN !
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1 µV1 µV
1550 ± 340 pΩ
1550 ± 340 pΩ
Results from Measurements Performed on 30 Oct. at 5000 ADCwith COMPENSATED DQQDC Detector
520 ± 110 pΩ / Splice520 ± 110 pΩ / Splice
671 ± 43 pΩ
671 ± 43 pΩ
335 ± 22 pΩ / Splice335 ± 22 pΩ / Splice
500 nV500 nV
Can we measure better than 1 nΩ ?
YES WE CAN !YES WE CAN !
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97% Compensated Signal
Residual = 10 µV out of 400 µVResidual = 10 µV out of 400 µV
First Feeble Attempt at Compensation
4 A/s4 A/s
4 A/s4 A/s
Bus VoltageBus Voltage
375 µV375 µV
Uncompensated Bus SignalSerious Attempt at Compensation
Can we have a detection threshold better than 300 µV ?
YES WE CAN !YES WE CAN !
±300 µV±300 µV
4 A/s4 A/s
PC recapture !PC recapture !
Completely Compensated Bus Signal
Completely Compensated Bus Signal
Can we have a detection threshold better than 300 µV ?
YES WE CAN !YES WE CAN !
±20 µV±20 µV
Conclusions fromPreliminary Testing
• Signal noise is amazingly insensitive to cable routing.
– This allows practical routing in the cable trays.
• Barring any unforeseen noise issues, sub nΩ resolution should be possible.
• A 300µV real time early warning threshold is practical.
– But keep in mind that saturation at high field or magnetization at low field may spoil compensation slightly.
– Some variation in splice resistance must be tolerated.
– Some variation in electronic component noise must be tolerated.
– And many unexplored and hence unforeseen noise sources may spoil and consume our threshold margin. (TGV, Bastille Day, etc.)
– A healthy margin must be maintained, as false trips may keep the Higgs away.
– Only after operational experience with the entire system will we know if the threshold really needs to be increased for stability or possibly could be decreased to provide added security. (The threshold needs to be secure but flexible.) YES WE CAN !YES WE CAN !