Implementing Simulation Across ETI Elektroelement: Future-proofing via Surrogate Models

Established in Izlake, Slovenia in 1950, ETI Elektroelement d.o.o. has grown into one of the world’s leading providers of products and services in the field of electrical installations, distribution of electrical energy for low and medium voltages, and power electronics.   

Part of ETI’s wide product portfolio are residual current devices (“RCDs”), which protect users from electric shock. So-called differential current can be fatal if a person comes into contact with a device receiving voltage, and the current flows through their body while being grounded. Fast and reliable operation of RCDs is crucial when breaking an electrical circuit.  

One part of an RCD is a differential transformer that detects the difference between the sum of the currents flowing into it and the sum of current flowing out of it. In the event of a faulty current, a difference between the sums appears. As a result, voltage is induced in the secondary winding of the transformer, which sends an electrical signal to the electromechanical relay that triggers a switching mechanism and opens up the electrical circuit.  

Challenge  

In the very competitive electrical equipment supplier industry, the price and quality of products are an ever-increasing challenge. Quick adjustments to the market and customers are one of ETI’s major advantages. In an era of accelerated automation, the swift development of accurate simulation models, on the basis of which initial prototypes are made, is also crucial. Deficiencies in the development of new components typically lead to project delays, resulting in greater costs.  

When developing circuit breakers with differential current protection, one of the main challenges is calculating the dimensions of the differential transformer’s core. In addition to the fact that its dimensioning is key to the quality performance of the product, the core is the device’s most valuable component, making optimization of its dimensions crucial.  

Solution   

To design a core to be used in ETI’s new generation of residual current circuit breakers (“RCCBs”), a COMSOL Multiphysics model was created using magnetic fields physics. The model consists of primary winding where load current is defined, a differential transformer with parameterised geometry and magnetic properties and secondary winding where induced voltage is observed. After the model’s validation, a COMSOL application was created that allows for swift modification of core geometry, the current through the primary winding, varying the magnetic properties of the material used in the core, and calculating the voltage generated in the secondary winding.  

This project also involved integration of the surrogate model functionality within COMSOL Multiphysics to enhance the simulation process. To achieve this, a comprehensive set of simulation data was generated using a design of experiments (“DOE”) approach, covering the input parameter space effectively.  

This data was used to train a surrogate model to ensure it’s ability to reliably predict simulation outcomes. After validating the model against outside data, it was integrated into our COMSOL application. This allowed for rapid evaluations of system behavior under various parameter configurations, significantly reducing the time required for optimization and sensitivity analysis compared to use of a full simulation model.  

Results  

By integrating the surrogate model into our COMSOL application, engineers without extensive knowledge of finite element analysis (“FEA”) can now easily perform complex simulations and analyses. This accessibility has democratized the simulation process, enabling more team members to contribute to optimization and decision-making efforts efficiently. Additionally, the surrogate model has significantly reduced the time required for simulations, allowing for quicker iterations and faster project completions. By developing the application, we are also capable of predicting the impact of core parameter deviations, inside or outside the tolerance areas, and thus able to precisely define them and eliminate potential errors in production in the event that the value of a certain parameter changes. Via this streamlined application, we can now distribute it across our organization, enhancing overall productivity and fostering collaborative innovation.  

Summary  

Challenge: In a highly competitive industry, maintaining product quality and cost-effectiveness is crucial. Accurate simulation models for circuit breakers with differential current protection are essential for preventing delays and ensuring high-quality performance, particularly toward precise dimensioning of the differential transformer core.  

Solution: We developed a COMSOL Multiphysics model using the physical properties of magnetic fields physics to design a new core for our RCCBs. By integrating surrogate model functionality and generating comprehensive simulation data through a DOE approach combined with deep neural networks, we have created an application that allows for rapid adjustments to core geometry, magnetic properties, and simulation conditions.  

Result: Surrogate model integration has enabled engineers without extensive FEA knowledge to perform complex simulations, democratizing the process and enhancing team contributions. This approach has significantly reduced simulation time, allowing for faster iterations, improved prediction of parameter deviations, and enhanced product quality, leading to greater overall productivity and innovation across the organization.  

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