Analysis of Multiple Load Cases in a Single Test Bench Environment at HUBER + SUHNER

Whether by train or car, the mobility of the future will be electric in terms of energy transition. In case of railway networks already powered by electricity, trains have prevailed. On the road, hybrid and electric vehicles are becoming increasingly important. Also, in aviation, electrically powered aircrafts are on the rise. Electric means of transport should be energy-efficient, safe, and comfortable. Thanks to high-quality connection technology from HUBER + SUHNER (H + S), this becomes possible.

The company HUBER + SUHNER develops and produces cables, connectors, and cable systems for data and energy transmission, offering high-frequency and low-frequency technologies as well as fiber optic products from a single source.

Problem

Cables on electrical charging stations must withstand a variety of loads, yet work reliably over a long period of time.

Solution

HUBER + SUHNER, the world leader in interconnect technology, uses state-of-the-art automated test rigs with robots to test its cables, able to appraise a wide variety of load cases. The complete measuring chain from HBM is used for acquiring the necessary measurement data with large data volumes and high precision requirements.

Result

The modern testing concept of cables enables exact and reliable lifetime analyses for cables in charging stations—a special, yet significant, contribution to the future of electromobility.

Cables and cable connections in an ice block
Cables and cable connections in charging stations are subject to extreme conditions.

The HUBER + SUHNER RADOX® cables and their use in HPC high power charging system

In charging stations, cables and cable connections are exposed to strong vibrations, extreme temperatures, and aggressive fluids throughout their lifetime. There are rather high demands of the quality, longevity and temperature resistance of the cables and systems used. RADOX® multicore cables have high resistance and resistance to heat. They have been specifically developed for the construction of compact and lightweight high-performance equipment.

To ensure continued use in electrical charging stations, the cables are tensioned for testing in a torture bench and subjected to millions of load cycles.

Test bench setup

Modern bench-top robots characterize the cables to the predefined loads. For this purpose, different load profiles are run through at different ambient temperatures in a climatic chamber. The cables are also visually checked during the test to determine possible changes to the surface of the insulation jacket.

In order to obtain stable and traceable measurement data, HBM's complete measurement chain is used for the long-term tests – from the precise sensors to the data acquisition to the intuitive software, which analyzes large amounts of data in just a few clicks. A reliable measuring chain without system breaks is thus guaranteed.

According to Mr. T.-M. Schmid, a technician at H + S, this aspect opens up new dimensions for the use of modern robots and their degree of freedom in the test bench environment. Thus, for example, several load cases can be covered; whether it be a bending test, torsion test or complete 1: 1 simulated movements, all possible load cases can be realized with a working machine.

The trick is to find and record the relevant measurement points and quantities to detect material changes in the cables. For this purpose, sensors for force, torque, rotation angle, and temperature are used. The data acquisition system QuantumX and the catman® software from HBM are used for data acquisition and analysis.

Fatigue analysis with catman®: Classification method (peak-valley analysis)

For long-term tests, the maximum forces or torques that occur must be precisely determined repeatedly. For this purpose, the analogue pickup signals are digitized and recorded with high precision and high dynamics. As the measurement takes several months, significant amounts of raw data have to be analyzed.

Thanks to an intelligent data reduction method in the catman® data acquisition software, only the relevant minima and maxima of the sensor signals are stored, which enables a considerable data reduction. At the same time, a cycle counter runs, evaluating the minima and maxima. The test can be stopped after a given number of cycles (through intelligent triggers). The statistical trend of the minima and maxima signal values, in turn, is also analyzed online and included in the event or alarm monitoring. In the simplest case, alarms can change the signal color (blue-> red) or generate actions such as an entry in the logbook, push message to the mobile phone, camera activation, storage of all raw data, and much more.

During the measurement, the data is periodically secured in a defined time secured distances. The counter is not affected. To stop the measurement, a defined maximum change of the minima or maxima values is used as a stop trigger. The service life of the cables is determined by the number of real load cycles achieved. No programming skills are required to realize this demanding measurement and test task. Electric mobility requires intelligent solutions. H + S is ready to make a significant contribution here. HBM provides support for this process with quality tools for metrological evaluation in the test. In addition, HBM offers further opportunities for electrical tests as well as for the performance and efficiency analysis of batteries.