Upgrade of the Automatic Measurement System for the Electrical Verification of the LHC Superconducting Circuits

Impedance measurements of superconducting circuits routinely serve as means to anticipate their dynamic response and validate their electrical integrity. Usual procedures involve performing tests on non-powered systems during commissioning and maintenance periods. However, impedance measurements might have a strong potential in diagnostics of powered superconducting circuits as well. In particular, they should allow for on-line fault monitoring, enhanced quench detection, and deeper insight into the electrical properties of the circuits such as impedance variations or non-linear effects in the operational conditions. This paper outlines the design of an experimental platform enabling such an evaluation. In essence, this system is capable of injecting electrical stimuli into a magnet circuit and capturing the response. The acquired data are processed in order to extract circuit characteristics, in particular the impedance and its temporal evolution. In addition to discussing key design considerations related to measurement performance such as bandwidth, resolution, and sensitivity, the paper explores how to maintain transparent operation with respect to peripheral components such as the power converters and quench protection systems. Finally, the paper presents the validation campaign of the designed solution. The validation consists of two stages, including non-powered and powered superconducting circuits. The former case compares performance of the system to a state-of-the-art industrial impedance analyser, while the latter focuses on the impact the system has on peripheral components. Presented conclusions provide guidelines for front-end instrumentation design and data processing in order to enhance performance evaluation of superconducting circuits in their entire operational spectrum.

Section: A Experimental Setupmentioning

confidence: 99%

Enabling Real-Time Impedance Measurements of Operational Superconducting Circuits of Accelerator Magnets

Christensen,

Bednarek,

Denz

et al. 2024

“…individual magnets, or their instrumentation such as voltage taps and quench heaters. Each test can be composed of several to few hundreds automatically performed resistance measurements using equipment described in [3], [4], [5], [6], [7], and [9].  Complex impedance measurementsperformed on complete superconducting circuits or individual magnets, at frequencies from 1 Hz to 100 kHz and stimulus current below 1 A peak.…”

Section: Tests Required For Elqamentioning

confidence: 99%

“…A dedicated gain/phase analyzers are integrated in the test systems and the same automated switching circuitry as for resistance measurements is utilized in this test. Details of the setup are described in [3] and [6]. All measurement data are checked against predefined thresholds and historical values [4] in order to obtain the test result.…”

Section: Tests Required For Elqamentioning

confidence: 99%

“…3) Following the hardware upgrade of the main mobile EL-QA test bench in 2012 described in [6] and with experiences gained during LS1, a number of improvements was introduced in the low voltage measurement system. In the software part, the upgrades provided improved precision for voltage tap sequence identification, an additional four-wire resistance measurement performed on each coil of main circuits, and general code optimizations.…”

Section: Preparation For Ls2 (2015 -2018)mentioning

confidence: 99%

See 1 more Smart Citation

Preparation and Execution of the Electrical Quality Assurance Program On the LHC Superconducting Circuits During the Second Long Shutdown

Ludwin

Bednarek

Bednarski

et al. 2021

Self Cite

The electrical quality assurance (ELQA) of the superconducting circuits of CERN's Large Hadron Collider (LHC) during its second Long Shutdown (LS2) requires the execution of vast measurement campaigns. Each of 1658 electrical circuits as well as the instrumentation of each of the 1746 individual cryo-assemblies housing magnets, bus-bars and other components of the superconducting circuits, has to undergo a series of tests. At the beginning of the shutdown the tests are performed before and after the warmup from cryogenic temperatures. The same tests are repeated at the end of the shutdown, this time before and after the cool-down. As part of the dipole bypass diode insulation consolidation project and due to the replacement of a few non-conform magnets, additional electrical tests and measurements had to be performed throughout the shutdown period. With each measurement, electrical parameters like resistance, complex impedance, and the quality of the insulation are verified and stored for future reference. Due to the many thousands of measurements to be performed, multiple automated mobile test benches had to be developed for the different test types along with dedicated database and analysis software applications for the documentation and follow-up of the test results and the non-conformities observed. In this contribution we describe the collaborative effort between CERN and the Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences in Krakow during the three yearlong preparation process and experiences related to the execution of the ELQA activities during LS2 of the LHC.

New Measurement Techniques Used for the Electrical Quality Assurance of HL-LHC Superconducting Magnets

Ludwin,

Bednarek,

Da Rosa

2024

Self Cite

In preparation of the Large Hadron Collider (LHC) upgrade to High Luminosity LHC (HL-LHC), a number of new Nb3Sn magnets, including short model and prototype magnets, had to be electrically qualified. The process included a number of well-established Electrical Quality Assurance (ELQA) tests, such as electrical continuity checks of the magnet instrumentation, high-voltage (HV) insulation tests of the magnet and quench heater circuits, and impedance measurements. In certain cases, in order to fully understand the observed effects, we needed to introduce new measurement techniques, in particular both an impedance measurement at specific frequency and a HV insulation test of the quench heaters during high-current quenches of the magnet. Furthermore, in order to localize possible insulation faults, we performed HV insulation tests using an additional multichannel acquisition system with high sampling rate. In this contribution we present in detail the used measurement techniques, explain the safety aspects, and discuss the results and possible further work.