Proto DUNE SP Slow control temperature gradient monitor

Proto. DUNE SP – Slow control temperature gradient monitor Giovanna Lehmann – Xavier Pons CERN 11/05/2017 1

IFIC and Hawai CERN/DT temperature readout test setup results. NI-9238 Data ± 500 m. V Range, 24 bits resolution 4 simultaneous differential channels, 250 Vrms isolation Error ± 0. 07% MAX ~ ± 30 m. K MAX, Valencia setup ± 7. 5 m. K (Measured in a fixed 25Ω resistor) Input Impedance > 1 GΩ Current source Based on Texas Instruments Precise voltage reference application http: //www. ti. com/lit/an/sboa 046. pdf Hawai calibration: 1000µA ± 1µA ~ Max. Error ± 42 m. K Results: https: //indico. cern. ch/event/625009/ Valencia Calibration: 1000µA ± 0. 1µA ~ Max. Error ± 4 m. K 2

Proposal 1 - Temperature Gradient Monitor Readout Hardware - Input PCB. According the specifications. - The gradient monitors will be connected in the flange by means of DB 25 pin connector - So , 6 PT 100 (4 wires) x connector Proposal - To use a PCB for 6 U crate size with 4 DB 25 connectors - Capacity 24 PT 100 per PCB 6 U crate size PCB with 4 DB 25 connectors. CERN EP/DT 3

Proposal 2. Temperature Gradient Monitor Readout Hardware – Multiplexer. - To multiplex the 24 PT 100 signals to the same Analogue Input of the NI 9238 module - Multiplexer from Analog Devices Type ADG 707 - Datasheet - 8 differential signals per multiplexer - 3 multiplexers needed for 24 channels connected in cascade - Control bits from NI device 4

Proposal 3. Temperature Gradient Monitor Readout Hardware – Current source - One single current source per 6 U PCB, so for 24 PT 100 - Current source in serial for all PT 100 - The serialization is done at PCB level - Advantages - Removes the offsets generated by individual current source calibration - Easy calibration - Simple design - Cheaper - Disadvantages - If one PT 100 breaks we lose all chain. - This can be fixed by little bridge inside the PCB in the terminals/pad of the damaged PT 100 5

Proposal 4. Temperature Gradient Monitor Readout Hardware – Amplifying the working temperature range - With the present configuration we are wasting resolution and unused temperature range - The NI 9238 is measuring from 0 -250 m. V that with 1 m. A would represent that we measure from 33 K to 673 K - The solution is to adapt/amplify the signal between a working or nominal threshold to the measuring range and resolution of the NI module. - With the proposed voltage divider circuit the R 2 defines Amplification factor 1 to 1000 the working range which is amplified. - Proposed Instrumentation amplifier the Texas Instruments INA 116 Datasheet 6

Proposal 4. Temperature Gradient Monitor Readout Hardware – Amplifying the working temperature range - The following R values provides a working range of the PT 100 between 15 Ω and 75 Ω - Corresponds to 65 K to 210 K - If we apply amplification factor = 4 then the 60 m. V range is amplified to 0 - 240 m. V range that fits with the measurement range of the NI module. - If we chose narrow working range will have better resolution and accuracy. - Is this useful? 7

DB 25 FLANGE CONNECTOR MAPPING – COMPATIBLE WITH FLAT RIBBON TWISTED CABLE 8

DB 25 CERN CABLE SPECIFICATIONS 9

Backup 10

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Effect of the wire resistance of a PT 100 in 4 -wires connection in the SP Gradient monitor Analogue Input Impedance > 1 GΩ Valencia wires 34. 63 Ω/ 100 m; 20 m; 6. 926 Ω x 2; 13. 852 Ω Cern cable; 85 Ω/km; 20 m; 1. 7 Ω x 2; 3. 4 Ω Total Resistance; 17. 252 Ω Worst case room temperature 298 K; PT 100 voltage for 1 m. A current ~ 110 m. V; Current at the input = 0. 11 n. A Voltage drop due to 17. 252 Ω wire resistance ~ 1. 9 n. V (negligible? ) 12