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TP4 System – the main tool for ELQA

Mateusz Bednarek, CERN, GenevaJaromir Ludwin, IFJ-PAN, Krakow

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ELQA prior to the Powering Tests

All possible ELQA scenarios are described in EDMS document 788197

Main part of ELQA activities was marked in black.

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ELQA campaignTests are divided into 3 groups:• TP4 – Test Procedure 4

o HV and LV tests of circuits powered via DFBso 743 circuits

• DOC – Dipole Orbit Corrector check o HV and LV tests of circuits powered locallyo 914 circuits

• MIC – Magnet Instrumentation Checko HV and LV tests done locally on each magnet – it includes quench

heater qualificationso 1763 magnets.

TP1, TP2, TP3 were the test procedures suitable for testing DFBs at different stages of assembly. TP4 is the last test procedure that shall be applied once the DFB are connected to the magnet chain.

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Typical circuit tested with TP4• 2 current leads• Magnet chain

We need to check:• Electrical insulation of the circuit,• Continuity and resistance of the circuit,• Continuity and resistance of V-taps, • Check if V-taps are properly distributed along the CLs.• Make sure that the Pt100 is properly attached to the CL potential (to be

implemented)

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Complexity issue• For the MIC test there are 23 different types of

magnets.• The TP4 and DOC tests are even more varied

o 2-4 current leads in one circuit,o 7 types of current leads,o 6 types of connectors on DFBs

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Complete system overview

• A universal measurement system is needed to cover all configurations

• Measurements have to be automated• Results must be stored in the central database• Follow-up web page should be available as well

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Complete system overview

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The TP4 System• The TP4 system was recently

upgraded by the team from IFJ-PAN (aka HNINP), Krakowo The hardware of the old system was

unmaintainableo There were not enough spareso The old system was entirely dependent

on the Keithley multimetero The stability parameters of the old

system were acceptable, but there was a lot of room for improvement

o Many additional features were added in the upgraded version

• In this presentation we will focus on the current version of the system

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Hardware – general architecture

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Hardware• Measurement of the ohmic resistance of the highly inductive

superconducting magnet, requires extremely stable current.• Using voltage source with stable serial resistance gives better

results than using current source.• In order to stabilise the resistance of the current path within

the measurement system, we have decided to thermally stabilise the crucial elements.

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Hardware

• The resistors are used to set the working point of the power supply and for current measurement.

• 18 Internal voltage taps are routed to the inputs of the multiplexers.

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The temperature regulation• The temperature regulator is based on the microcontroller,

connected to the computer via USB port.• Regulation is done in two stages:

o Temperature of internal part is controlled by proportional-integrating regulator using 4 heaters. The current relays PCB and resistors are enclosed in thermally insulated box.

o Temperature of external part is controlled by proportional regulator using set of heaters and fan

• Parameters of regulators are stored in the EEPROM, and can be modified from the level of LabVIEW software.

• Since we know the power that will appear on the resistors during the measurement, we can use feed-forward method to stabilise the temperature of the resistors. The feed-forward control is done by altering the integral term of PI regulator.

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Hardware

The system is equipped with 84 inputs:• 18 internal,• 66 available on the front

panel.

Having 4 independent 1 of 84 multiplexers gives following possibilities:• Measurements of any

two voltages inside the system and on the device under test

• 4-wire resistance measurements

• Transfer function measurements using freely chosen reference impedance

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PCBs arrangement• Multiplexers are fitted

into a 3U crate,• Power supply is located

in a separate 1U case

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Shielding

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Current status of the system• All multiplexer crates are assembled and

tested,• Measurement instruments are mounted

on the available trolleys,• Most of the measurement cables are

ready,• During the development of the system

emerged an idea of replacing Keithley multimeter with two PXI DMM cards. o The migration is ongoingo SM18 tests have shown that the migration is

not going to be too complicated

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Debug consoleApart of the standard measurement applications (TP4, DOC, MIC) there is a “debug console”• Access to all the measurement instruments in the system,• Low level control of the multiplexers and the thermostats,• Usage of functionalities inaccessible for standard applications,• System self testing capability,• Advanced circuit

diagnostics,• Designed to be

used by experts only.

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SoftwareDatabase is the central part of the system. It stores:• Reference data describing circuits• Test content• Validation conditions• Configuration parameters• Calibration parameters• Results

Signal translation in low voltage test applications. Measurement results validation process.

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Open questionDuring the MIC tests, we are powering the measurement system form 24 VDC batteries of Pefra tractor.There are rumours, that the tractor type at CERN may change.In such case we would have toadapt our hardware and the work flow.

Source: Model 507 datasheet

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Conclusions• TP4 is a very versatile system perfectly suited

for the complex LHC circuits,• Upgrade works are almost finished,• If needed the TP4 platform may be used for

new types of measurements,• The database system makes it a reliable and

scalable system,• A test on a highly inductive superconducting

magnet is still missing

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AcknowledgementsThe new TP4 is a very complex project.Many details had to be carefully designed in order to achieve expected performance, both from electrical and mechanical points of view.Credit for solution of those problems goes mainly to the IFJ-PAN team:• Piotr Jurkiewicz, • Marek Ruszel, • Ryszard Tarczoń • and others, who are not mentioned here, but realisation

of this project would be impossible without them.

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Thank you for your attention!

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Back-up slides

For the discussions

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Keithley -> PXI controversy• Pros of having a PXI on board

o Reduction of time needed for the measurements,

o Increased precision as the current can be measured at the same time as the voltage across a component of the circuit,

o Decreased wear of the multiplexer relays,o Increased versatility of the system

• Conso Increased complexity of the user interface,o Communication with the central DB will need to

be modified

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Example screenshots