Mersen, the electrical protection specialist, operates a test center at its Saint Bonnet de Mure site, near Lyon. The company's highly qualified experts carry out over 10,000 tests a year to verify the performance and reliability of numerous products such as fuses. Mersen, a global expert in electrical specialties and advanced materials for high-tech industry, set up a test laboratory at its Saint Bonnet de Mure site exactly 40 years ago. The 4-storey, 1,600 square metre complex, with doors over five metres high, houses the electrical engineering specialist's extensive testing and research facilities.
A wide range of electrical safety tests
" The laboratory is divided into two areas "explains Ludovic Derouen, head of high-power testing. " A first laboratory for high-power, high-short-circuit tests, and a second for low-voltage, environmental and mechanical tests. "Every year, on 50 test benches, our staff carry out over 10,000 electrical, dielectric, mechanical and environmental tests. Mainly on fuses and fuseholders, such as those protecting semiconductors, cables or motors. " We also test the entire range of Mersen products, such as laminated bus bars, overvoltage protection devices (SPDs), power capacitors and certain products manufactured by Mersen for the railway industry. "adds Ludovic Derouen. " We also regularly support external customers in their development projects. ". In the aerospace industry, for example, Mersen is testing cables for future electric aircraft. " Another topical example: for electric vehicles, we are testing pyrotechnic fuses that isolate battery packs in the event of a fault or crash. ".
Voltages up to 43 kilovolts
The high-power test laboratory characterizes the breaking capacity and transient current resistance of fuses, as well as short-circuits with very high current gradients (di/dt), all in alternating current (AC) and direct current (DC). These high-voltage tests require the use of high-performance equipment such as fiber-optic measurement interfaces with high acquisition frequencies. The power area is equipped with five test platforms, generating a wide range of DC and AC currents and voltages. One of these platforms is connected directly to the 20kV grid (3 MVA); two others are powered by capacitor banks (high di/dt and 30 MW), the last two by internal generators (20 MVA and 400 MVA). The most powerful of these platforms can generate voltages of up to 43 kV and peak currents of up to 700 kA.
Specific test bench for EV products and semiconductor projections
The Laboratory therefore has two capacitor banks. One is specifically dedicated to electric vehicle applications with very low inductance. It is associated with a climatic chamber to carry out tests at nominal voltage and current in difficult conditions (-40°C to 150°C). The second is dedicated to the ultra-fast protections needed to protect semiconductors. It delivers up to 4 kV - 320 kA with a max di/dt of around 5 kA/µs. In addition to the usual low-voltage tests, based on AC/DC power supplies and cycling equipment, the environmental and low-voltage test laboratory is equipped with seven climatic chambers.
They are used to test components under extreme conditions (-40 to +200°C / 0 and 99 % humidity) and can be combined with cycled power supplies. " In salt spray tests, for example, we examine the behavior of fuses in air with a high salt content, to simulate coastal areas. "explains Ludovic Derouen. " This equipment, in accelerated cycling configuration, enables us to simulate the ageing of products in critical situations. "adds the expert.
Independent and impartial
All the technicians working at Saint Bonnet de Mure are highly experienced. The laboratory manager, Franck Sarrus, is also responsible for Research & Development at Mersen in Europe. Does this mean that the center is part of the R&D department? " Yes and no "Ludovic Derouen answers with a smile. Of course, the laboratory supports the Mersen Group's R&D activity, in a global context where testing resources are limited in this field. Quick and easy access to high-tech testing capabilities is therefore a very important factor, not to be underestimated for an R&D-intensive company like Mersen.
On the other hand, internal customers, including R&D, are treated with the same independence and impartiality as external customers, thus complying with standard 17025. " We test components and report whether or not they achieve the required performance. "says Ludovic. The test center's external customers are currently in the minority; over 90 % of the laboratory's capacity is currently used for internal requests. In the future, Mersen intends to offer more availability to these customers. "We are already ideally equipped for this next stage, with all the capacities and means necessary to meet the particular needs of our customers".
Worldwide coverage
Mersen Electrical Power currently operates three main electrical test centers worldwide. In addition to Saint Bonnet de Mure, there is a laboratory in Newburryport (USA) and another in Terrassa (Spain). " Ne work in close collaboration with our American colleagues in Massachusetts, particularly on UL testing."explains Ludovic Derouen: "Thehe American and French test centers are also complementary. Both are capable of operating in direct and alternating current, but at different current and voltage levels, enabling us to meet the needs of our products. ".
Laboratory accreditations
The Saint Bonnet de Mure test center is accredited by COFRAC, which ensures compliance with the ISO-17025 standard. Accreditation to the American UL standard is scheduled for 2022 - 2023. "In addition to the European, Chinese and Indian markets, we also test products in France intended for the American market".As regards potential future developments and to keep pace with new market needs, such as energy storage, e-mobility markets and the future DC grid, the laboratory is constantly investing in new dedicated equipment, as well as in training its technicians.