Measuring and testing technology - flexibly and efficiently control and analyze performance tests


As the market leader in the field of high-voltage bushings, HSP is driving efficiency in energy technology with innovations in the high-voltage sector. High-quality measurement and testing technology is required to meet the above-average performance in terms of operational reliability and life expectancy as well as properties that go beyond the thermal, electrical and mechanical requirements of the standards. HSP relies on Delphin for its heating test stand.

The history of HSP Hochspannungsgeräte GmbH begins in 1893 with the founding of Meirowsky & Co. in Cologne-Porz. In 1906, the company started with the production of condenser bushings. Since then, HSP has been the first point of contact for innovative and classic solutions in the field of energy technology. As a competent technology partner, the bushing experts pave safe and reliable paths for electrical current worldwide. In addition to high quality, the bushings for generators, transformers and switchgear are characterized by safety, durability and sustainability. Since 2014, HSP has also been manufacturing bushings made of resin-impregnated plastic fleece (RIS). Incidentally, the largest bushing ever built by HSP was 21 m long and weighed 18 tons. The basic prerequisite for high-quality products is good and accurate measurement technology. This is why HSP relies on devices from Delphin Technology AG for monitoring and evaluating the 92 thermocouples on its heating test stand.

Thermal testing with high current

"This is where we measure the temperature that occurs in our bushings during operating current and overcurrents," says HSP Testfield Engineer Daniel Zeus, explaining the task at the test stand. The test stand consists of boilers sunk 3 m into the ground and two aluminum columns with copper strips to which the bushings are connected. A high-current transformer applies up to AC 6 kA or 10 kA or DC 10 kA to the circuit at 50 V output voltage, thus heating up the respective bushing. "We then check that the temperature limits on the insulation are maintained. This task requires an accurate measuring system, but above all a large data memory, as each bushing to be tested is equipped with up to 80 thermocouples and a test cycle can take one to two weeks. The test is finished for us if the temperature fluctuates by less than 1 K within six hours," says D. Zeus. The biggest design challenge here is that, according to DIN EN 60137 VDE 0674-500 [3], measurements must be taken between the current-carrying conductor and the high-voltage insulation," says Senior Test Engineer Thomas Adams. The insulation is therefore tested to ensure that it can withstand the thermal loads. The insulation body must not become warmer than 120 °C or be more than 90 K above the ambient temperature. In order to meet its quality standards, HSP not only applies the rated current to its bushings, but also an overcurrent, either voluntarily or at the customer's request. After all, they should have a service life of at least 30 years. "We also push our own products to their thermal limits during the tests so that our development department can gain insights from them," says T. Adams.

Measuring and testing technology - modernization required

Two years ago, however, HSP reached the limits of the testing system. Due to the increased requirements, the company was looking for a more powerful temperature measurement and control system to which not only thermocouples but also fiber optic sensors could be connected. It should also allow remote monitoring. "Especially with our long test cycles, it's annoying if a fault goes unnoticed, we can't react and have to repeat the test," explains D. Zeus and continues: "We also wanted an easy-to-use system that offers more measuring channels - the previous one only had 20 - and can be flexibly expanded if required." Parameterization should also be easy to solve. In the end, HSP opted for the MSR system from Delphin. The physical proximity was of secondary importance, although the rapid availability of employees is particularly helpful during set-up and servicing. What was more important was Delphin's coherent concept and the speed with which it could be implemented. "The measurement technology offers over 90 channels and parameterization is simple using an Excel file that the software reads in," says D. Zeus. T. Adams adds: "Remote access also makes our work much easier, as we don't have an employee on site around the clock. It is also an advantage that the control system shuts down the test in a controlled manner if the temperature reaches a critical value and limit values are exceeded. This can sometimes happen, especially when testing new developments." The biggest challenge was that Delphin's measurement technology concept also had to manage external controls, such as the heating control for the oil and the control of the control transformers. Jan Tippner, Head of Sales at Delphin, emphasizes: "This requirement was also met with the help of our open solution. With the various available interfaces and communication protocols, we can actually connect our measurement and control technology to all available systems. If required, our experts can also write special drivers."

Flexible measurement and control technology

At the heart of the Delphin solution are two Expert Logger 300s, each with 46 analog inputs, to which the thermocouples can be easily connected. The FPGA-based Expert Logger combines state-of-the-art communication with sophisticated measurement technology. Measured values can be recorded precisely, stored autonomously and automatically transferred to the Internet or PC via USB, LAN, WLAN or LTE for evaluation. Signal processing using internal software channels considerably simplifies the actual measurement task. With the very flexible calculation channels, measured values can be further calculated and saved directly. Integrators calculate volumes or quantities directly from time-related measured values, such as mass or flow rates. Limit values can monitor measured values and be used to switch digital outputs or to automatically send e-mails. Not only are the inputs independent of the test station, the system can also be expanded as required. This fulfills two further flexibility requirements of HSP. Another control cabinet houses a ProfiMessage device and another Expert Logger, which are responsible for data communication via Profibus and control of external systems. Developed specifically for use as modular measuring, control and monitoring devices, ProfiMessage can be adapted to the respective application via a master/slave device concept and various IO modules. As the inputs and outputs are differential, highly accurate and electrically isolated - from each other and from the supply voltage - earth loops and sensors with potential do not pose a problem. The universal use of the inputs for voltage, current or temperature measurements makes the Delphin system extremely flexible. In addition, digital inputs are available as status or frequency inputs and digital and analog outputs. Despite the rather complex design of the test panel, installation and commissioning went very quickly. "It took just over eight months from the initial concept to the first test," reports T. Adams.

Operate, monitor and control from a single source

The HSP employees are particularly happy with the automation software, which they can use to operate, monitor and control their experiments as well as record and evaluate measurement data. Profisignal Klicks enables measurement data analysis directly in the visualization interface and in individual diagrams, regardless of the application. "This gives us a precise overview of the temperature curves at the measuring points of the feedthroughs and the difference to the ambient temperature," explains D. Zeus. Profisignal Klicks can also be used for process sequence control thanks to the integrated "Klicks" scripting language. As the program instructions are generated using context menus, it is no longer necessary to type in program texts and learn commands. This means that scientists, technicians and engineers can create and maintain their applications themselves, independently of IT specialists. "The test runs almost fully automatically. With Profisignal Klicks, we were able to create a separate interface for each type of implementation. This means we can easily set the target and limit values and have an overview of the entire test - even remotely," explains D. Zeus.

Detailed analysis at the touch of a button

Profisignal Klicks also helps with the analysis of measurement data. In addition to manual measurement data analysis in the form of diagrams, zoom, data export and statistics, automated measurement data analysis can also be implemented. J. Tippner goes into more detail: "The special feature of the script language in the context of measurement data analysis is that existing measurement files can be opened and edited using a script. For example, it is possible to automatically create reports, calculate minimum, maximum and average values over a specified period, automatically adjust trends or show or hide channels depending on user input or operating parameters." Reporting is also an essential part of the audit. "Our customers want detailed documentation of the test results. The software from Delphin also helps us very well in this respect," reports T. Adams. Profisignal Klicks creates informative reports with diagrams, tables and comments not only as a rigid PDF, but also as a dynamically operable document. Even data and graphics from the Profisignal options, such as alarm management, vibration monitoring or ODBC/SQL, can be combined in reports together with process and quality data. As the reports are automatically generated and archived on a time or event-controlled basis, Profisignal Klicks provides a detailed, easy-to-use method for quality assurance, quality verification and balancing. HSP is so satisfied with the measurement and control system from Delphin that the third test chamber planned for the high-voltage test laboratory in the near future will also be equipped with the MSR system from Delphin.

Delphin Technology AG
Lustheide 81 , 51427 Bergisch Gladbach
Phone 02204 / 97685-0

Frank Nolte,
Editor ETZ

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