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Max Lab IV particle accelerator in Lund, Sweden

Comsys became involved in their fourth particle accelerator project when Scandinova, who manufactures klystron modulators for particle accelerators and MRI scanning, approached us for the developing Max Lab IV site in Lund, Sweden. Referred to as “the brightest light source in the world,” Max Lab IV is one of two major recent research investments in Lund, the other being the ESS (European Spallation Source).

snow view of Max IV particle accelerator
Max Lab IV in Lund Sweden

Industry: Particle accelerator
Project Partner: Scandinova
Customer: Max Lab IV
Timeline: First contact in 2011, commissioning took place in 2013


To ensure compliance with the grid code and to mitigate harmonics and prevent power quality problems, Max Lab needed a harmonic compensation solution.

The Max Lab site includes multiple transformer stations, each with several modulators. To support the process of particle acceleration, the 18 on-site modulators are installed phase-locked and synchronous. This contributes to situation where the harmonics stack up perfectly and create increased distortion. Additionally, given that the harmonic load of each modulator is very high, combined they have an exacerbated load on the grid.

While the Max Lab IV modulators would be unaffected without compensation, neighboring industries and residences and the Max Lab IV facility itself would be impacted with electrical disturbances, machine tripping, and equipment breakdown due to the unstable power supply. Therefore, the customer actively sought a precautionary and preventative approach to avoid any potential problems.

ADF P300 Max Lab IV


Before applying a solution directly on-site, the function of the active filters were verified with a test in Scandinova’s research center in Uppsala. The purpose of which was to help them get an understanding of the harmonics in their machines and determine how ADF could be applied in the best way.

Once a solution was selected and commissioned, Max Lab experienced mitigated harmonics from the second order up until the 37th harmonic.

Products in this installation:

  • One ADF P300 per transformer (seven systems total)

  • One PPM 300 per modulator (18 modulators)

By putting one ADF module on every transformer and compensating the harmonics locally (as opposed to central compensation), we mostly eliminated harmonic loading on the medium voltage level—which is where Max Lab faced regulatory requirements.

Max Lab IV particle accelerator


After commissioning, we conducted a verification measurement to ensure the active filters were compensating the site as designed. The performance has been verified* by third party consultants, which ensured that the whole project complied with the grid code.

graph of harmonic amplitudes present in uncompensated current
Uncompensated load current (from one of the 18 modulators) – harmonic amplitudes present in current: 2,3,4,5,6,7,8,9,11,13,15,17,19,21,23,25,27,29…
Graph no harmonic amplitudes present in compensated load current
Compensated load current – harmonic amplitudes present in current: none.

Since then, important research with implications for renewable energy, disease control, and more has continued at Max Lab. See what they’ve been up to here.

*This test was requested by the grid owner, and the measurement was made by engineering consultants.

Aerial over max iv