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Reaching for the stars

Power supplies for the most accurate telescopes in the world

The cameras of the 12-meter telescopes are being powered by PULS DIN rail power supplies. (Source: CTA Observatory / G. Pérez, IAC, SMM /

The Cherenkov Telescope Array Project (CTA) is currently one of the most ambitious projects in astrophysics. The result will be the largest and most accurate gamma ray observatory in the world. DIN rail power supplies from PULS play a decisive role in this project.

The CTA observatory consists of more than 100 telescopes of various sizes – with 4, 12 and 23m mirror diameters – installed in the northern and southern hemispheres. These highly sensitive telescopes enable scientists to locate high-energy gamma rays throughout the universe. The telescopes are about ten times more accurate than existing instruments. As a result, researchers expect groundbreaking new information on inter- and extragalactic objects. A completely reliable and low-maintenance operation of the telescopes in various different climate zones is decisive for the success of this project. The selection of the right power supply plays an important role here.

PULS DIN rail power supplies are known for their high efficiency values, compact design, long lifetime and robustness in harsh ambient conditions. In the CTA project, these are the key requirements for the power supplies. The devices are supposed to guarantee the constant energy supply of the telescopes for years to come.

Looking for answers using nearly 1800 pixels

The CTA project consists of over 100 telescopes in various sizes. (Source: CTA Observatory / G. Pérez, IAC, SMM /

The goal of the CTA project is to answer some of the unresolved questions in astrophysics. For example, the observatory will help scientists to understand the effects of high-energy particles in the evolution of cosmic systems and to search the cosmos for new VHE gamma-ray sources in the future.

Prof. Ulrich Straumann and his team from the Physics Institute of the University of Zurich are also involved in this ambitious project. Together with other international teams, they are working on the development of a camera for the 12m telescope. The telescope therefore has a mirror with 12m diameter and a focal length of 16m.

The camera, which is installed directly in the focal point of the huge telescope, weighs almost two tons and consists of 147 modules with 12 light-sensitive detectors each. In addition to this, there is a built-in amplifier as well as digitising electronics, which provide the option for decentralized data storage. The entire camera contains nearly 1800 individual pixels. The field of view of the telescope is approximately 7°, resulting in a sensitive, hexagonal camera surface with a diameter of 2m.

Power supplies with high efficiency, compact size and long lifetime are crucial

For a project of this size and scientific scope, selecting the most efficient power supplies is particularly important. After intensive research, the developers of the University of Zurich decided on the DIN rail power supplies from PULS. The AC/DC converters CPS20.241 (24V / 20A) and QT40.241 (24V / 40A) as well as the the MOSFET redundancy modules YR40.242 and YR80.241 are used in the control cabinet of the camera. As a precaution, the power supplies are installed in a redundant system. This ensures the availability of the camera at all times – despite the harsh environmental conditions.

The Swiss scientists particularly praised the high efficiency (QT40.241: 95.3%, CPS20.241: 94%), small width (QT40.241: 110mm, CPS20.241: 65mm) and long minimum service life (QT40.241: >7.5 years, CPS20.241: >10 years, both at full load and +40°C ambient temperature) of the PULS DIN rail power supplies. “With the PULS power supplies, we can easily achieve the required output power of 4.5kW within the available space,” explains Dr. Achim Vollhardt, who is involved in the camera project as an Electronics Engineer.

His colleague, Senior Scientist Dr. Arno Gadola adds: “The documentation of the power supplies is very detailed and contains extensive information about their lifetime expectancy. This way we can easily estimate the lifetime of the power supplies under our operating conditions.”


1-phase DIN-rail power supply

24V, 20A


  • AC 100-240V wide-range input
  • Width only 65mm
  • 94.0% efficiency
  • ATEX and IECEx approved
  • 20% output power reserves
  • Full power between -25°C and +60°C
  • DC-OK relay contact
  • Current sharing feature for parallel use

Learn more about the CPS20.241


3-phase DIN-rail power supply

24V, 40A


  • 3AC 380-480V wide-range input
  • Three input fuses included
  • Width only 110mm
  • 95.3% efficiency
  • 50% BonusPower®, 1440W for up to 4s
  • Full power between -25°C and +60°C
  • Remote control of output voltage

Learn more about the QT40.241


MOSFET redundancy module

24V, 40A


  • For N+1 and 1+1 redundant systems
  • Dual input with single output
  • 160% (65A) peak load capability
  • Reverse input polarity protection
  • Full power between -40°C and +60°C
  • Width only 36mm

More about the YR40.242


MOSFET redundancy module

24V, 80A


  • For N+1 and 1+1 redundant systems
  • Dual input with single output
  • 160% (130A) Peak load capability
  • Reverse input polarity protection
  • Full power between -40°C and +70°C
  • Width only 46mm

More about the YR80.241

Full potential in harsh ambient conditions

The CTA project is an application that demands everything from power supplies: challenging technical and climatic conditions, the highest demands on efficiency, and a global application with the lowest possible maintenance effort. But it is precisely in this environment that PULS power supplies show their full potential.

For the Swiss PULS Electronic GmbH, the close cooperation with the University of Zurich in conjunction with the CTA gamma-ray observatory is a particularly exciting project.

“If our power supplies can contribute to our understanding of the universe and our existence, then this is not only a technical and economic success, but also a great personal pleasure and satisfaction for me and our company,” says Heinz Setz, Managing Director of PULS in Switzerland.

Learn more:

The CTA project intends to install over 100 telescopes in various sizes throughout the northern and southern hemispheres. (Source: CTA Observatory / G. Pérez, IAC, SMM /