| dc.description.abstract | Going electric is an important step toward a more environmentally friendly world by reducing greenhouse gases. Some electrical devices might be able to withstand a short-term overloading, which for example can be used for fast charging of batteries or vehicles. A MV switchgear is one of the devices which have the possibility to handle a short-term overloading, without exceeding the IEC temperature limits. The objective for this thesis is to develop and implement a thermal model which predicts the temperature rise of a specific MV switchgear, based on defined subsystems. This can be used to determine the possible overload time when different currents are applied. Real temperature rise tests with different applied currents are executed to gather data for evelopment of the thermal model’s parameters and for verification. Parameter values like thermal time constants, heat transfer coefficients, resistance and surface areas are determined. The thermal model is implemented in Python 3.7 where the simulated thermal model is compared to the real temperature rise measurements. The thermal model is able to simulate the temperature rise of the system with changing accuracy for different test cases. When only the initial current is applied until steady state, the average error is less than 10%. In the overload cases, some adjustments are needed to predict accurate temperatures. When the thermal time constant is adjusted, the thermal model is able to predict the temperature rise of the subsystems with a deviation less than 10% compared to the real data. Based on the thermal model, possible overload times for different applied currents is determined and presented. | |
