Upgrade of the Automatic DC High Voltage Multichannel Insulation Tester for Superconducting Circuits of the LHC

Since the assembly phase of the Large Hadron Collider (LHC), and throughout all technical stops, the Electrical Quality Assurance team has conducted over 100 000 high voltage insulation tests on superconducting circuits of the LHC and their components. These tests were initially performed using automatic DC high voltage multichannel insulation testers, developed in 2005 [2]. Over two decades of successful system utilization a number of upgrades have been introduced, which included design of new data acquisition module in 2013, complete hardware modernization in 2018, introduction of new features in firmware and software in 2024, and integration of high-speed acquisition unit for recording breakdown events in 2025. Additionally, the system's software, database, and web applications have been progressively upgraded to optimize data availability and test follow-up. In this contribution we are presenting the current state of the automatic multichannel DC high voltage tester used for qualification of the LHC superconducting circuits, as well as discussing the design choices, measurement results, and key lessons learned, highlighting the impact of upgrades on system efficiency and diagnostic capabilities.