LabVIEW Based Test and Calibration System for Cryogenics

Dorota Wanda Jelen

Outline

1. Commissioning of cryogenic crates using Mobile Test Bench

1. The Mobile Test Bench2. Cryogenics crates and equipment – types of transducers

and actuators3. Electrical tests - instrument, cable & card tests

2. Test and calibration systems for pressure sensors1. Low pressure bench2. High pressure bench

CO

MM

ISS

ION

ING

OF C

RYO

GEN

IC

CR

ATES

US

ING

MO

BILE

TES

T B

EN

CH The Mobile Test Bench (MTB) was a custom Automatic Test Equipment system,

designed for operation in the LHC tunnel. Its purpose was to perform the final test of the cryogenic FIP crates and their attached sensors and actuators.

Mobile Test Bench based on PXITH

E P

RO

BLE

M

Need of automatic system for testing of the cryogenic acquisition electronics

Large amount of devices to be tested in relatively short time Synchronization with main database for retrieving the crates

configuration Internal automatic signals routing between device under test and

testing equipment simplifying operators actions, reducing test duration

SOLUTION:

MTB test

cables

Tunnel cables

Connect

ors

panel MATRIX

for signals routing

DMM1

DMM2

Current generator

Resistance simulator

CPU

FIP BUS

FIP CRATE

Sensors/actuators

TH

E M

OB

ILE T

EST B

EN

CH

MTB was based on the PXI platform by National Instruments

The PXI rack houses:1. A controller by NI running on Win XP2. Two FIP communication cards3. A 276 x 8 matrix module by Pickering4. One programmable resistor module

by Pickering 5. Power supply card6. Multimeter card7. GPIB interface

Apart from PXI, other components are:8. Keithley 2400 SourceMeter9. Keithley 2182 NanovoltoMeter10. A connector panel11. One UPS

CRYO

GEN

ICS C

RATES

AN

D

EQ

UIP

MEN

T

Types of cards and transducers:1. DI – valve card2. TT/PT/LT cards – temperature, pressure and level transducers cards3. FIP card – each consist of 2 FIP agents (left for sensors and right for actuators)4. EH cards – electrical heaters cards

Purpose of the tests was to verify that each instrument:5. was physically present at the machine6. was correctly wired and properly connected7. had the expected resistance value

ELE

CTR

ICA

L TES

T

- INSTR

UM

EN

T T

ESTS

Tem

pera

ture

Pre

ssure

Temperature transducer TT Two types: CERNOX and Pt100 pinout: subD 9 (M) and fisher 12 (M) 4-wire resistance test Resistance between U+ and I+

Pressure transducer PT Types: 20 bar, 4 bar, 350 mbar pinout: subD 9 (M) and 6 MIL (M) 4-wire resistance test Resistance between U+ and I+ Resistance on Pt1000 Short circuit against the ground

Heliu

m level

Level transducer LT Probes lengths: 150mm, 400mm, 600mm pinout: subD 9 (F) and 4 MIL (M) 4-wire resistance test Resistance between U+ and I+

ELE

CTR

ICA

L TES

T - P

IN T

O P

IN C

AB

LE T

ES

T

1. to track down every electrically measurable error within a cable - instrument assembly. (open or inverted connections, short circuits and low insulation resistance values)

2. MTB measured the resistance between all pin combinations of a cable connector and the resistance between each pin of the connector and ground

3. In principle, only measurements between active pins (U+, U-, I+, I-) that belong to the same sensor produced relatively low resistance values. All other combinations implied an open circuit (any resistance value above 1MOhm was considered open circuit)

ELE

CTR

ICA

L TES

T - C

AR

D T

ES

T

to validate the correct functionality of each electronic card of the crate.

TT/PT card example1. TT/PT cards are able to measure TT or PT2. TT/PT cards measure the attached sensor using the 4 wire method3. CERNOX resistance ranges from some ohms at ambient temperature to tens of

kOhm at cryogenic temperatures. TT cards have 3 measuring ranges:

1. 30 – 300 Ohm (excitation current 100uA)2. 300 – 3 kOhm (excitation current 10uA)3. 3k – 30 kOhm (excitation current 1uA)

TT card test consist of 9 set-points 3 for each range

Measurement procedure:1. The setpoint resistance is set in the programmable resistor module.2. The matrix connects the resistance to the MTB instrumentation (Keithleys ).3. The Keithleys perform a measurement of the resistance (Bench

Measurement).4. The matrix disconnects the resistance from the Keithleys and connects it to

the TT card under test through the MTB cable that is plugged to the crate card.

5. The TT card performs measurements of the resistance (multiple times per second). MTB acquires measurement data through FIP (FIP Measurement).

6. MTB software compares the two values (Bench Measurement and FIP Measurement). The step is marked as “OK” if the relative error is less than 0,3%.

TES

T A

ND

CA

LIBR

ATIO

N S

YS

TEM

S

FOR

PR

ES

SU

RE S

EN

SO

RS

Click icon to add picture

Low pressure bench – on the rightClimatic chamber (temperature module of pressure bench) – on the left

LPB

- LOW

PR

ES

SU

RE B

EN

CH

LPB is based on the PXI platform by National Instruments

The PXI rack houses:1. An embedded controller by NI

running on Windows XP2. Multimeter card3. GPIB interface

Apart from PXI, other components are:4. Two pressure gauges with

different ranges allow to perform high accuracy tests from near 0mbar to 130mbar

5. PLC controller for controlling four electromagnetic valves

6. Three pumps (one is turbomolecular pump)

7. 5 DMM’s8. Power supply system

Software:9. LabVIEW for controlling all

system; modular structure for reusability in other projects (temperature, pressure, PID, sequencer)

10. MatLab for data analyses

HPB

- HIG

H P

RES

SU

RE B

EN

CH

HPB is based on the PXI platform by National Instruments

The PXI rack houses:1. An embedded controller by NI

running on Windows XP2. Multimeter card3. GPIB interface

Apart from PXI, other components are:4. Two pressure gauges with different

ranges allow to perform tests - from pressure near 50mbar to 20bar

5. Three electromagnetic valves6. Pumps and bottle with synthetic

air

Software:7. LabVIEW for controlling system

thank you for your attention