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Hydro-generators with skewed armature slots have damper interbar currents that flow transversely between the damper bars through the core. The interbar currents may involve harmonic and local overheating issues. The interbar resistance is a vital factor that affects the distributions of interbar currents and damper bar currents. A multislice finite-element model with integrated interbar circuit is...
A highly accelerated power cycling test platform using current source converter for SiC-MOSFET power modules is proposed. The control principles of delta and average junction temperatures are introduced. By using isolated thermal fibers, the junction temperature (Tj) variations can be monitored during the test process without removal of silicone gel. The power module is tested in the conditions of...
This paper proposes tower grounding resistance measurement method on the basis of three-electrode method and clamp meter, explains the structure of measuring device including host measurement structure and Rogowski coil current sampling structure, which host is used for grounding resistance test and Rogowski coil for Tower foot failure assessment. This paper analyses the innovative of device by high...
The current zero period of vacuum arc determines the breaking performance of vacuum circuit breakers, and post-arc current is one of main parameters of current zero period. DC vacuum circuit breaker is one practical solution to solve the bottleneck of DC transmission circuit breaker. It is difficult to measure the post-arc current, when artificial current zero method is used to break the DC short...
High voltage circuit breakers are most important protective device in power system. Dynamic contact resistance measurement (DRM) is considered to be an effective assessment technique for contact ablation which has been widely used for many years. However, the contact resistance curves will be influenced by many factors, such as injected current and velocity. In power systems, circuit breakers often...
The use of virtual instruments has a very important role in both specialized laboratories and academic ones. Because it is a modern method, it provides increased comfort in monitoring electrical circuits in the long term, as well as reduced costs of implementing and developing laboratories. This paper deals with the efficiency of virtual instruments in monitoring electrical circuits as compared to...
This paper presents a study about the impulse impedance of grounding grids based on experimental measurements performed within a testing field developed for this purpose. It considers an extensive number of measurement sets performed in grounding grids with different dimensions and topologies. The main goal is to evaluate an appropriate procedure to be employed during field measurements, as well as...
This paper presents a procedure to acquire precise measurement data of the output characteristics with a custom-made setup. In comparison to datasheets and common curve tracer measurements, the measurement range is extended and the accuracy improved. After deriving the theoretical minimal switching energy for semiconductor switches in a half-bridge configuration, possible operating points of the latest...
This paper describes an improvement of the Modified Opposition Method used to precisely estimate switching losses of SiC and GaN transistors, in order to accurately design power converters. This method estimates separately turn-off and turn-on energies, by two different operation modes. The aim of this work is to improve accuracy of switching energy estimation by considering meticulously losses on...
This paper presents the study, design and simulation of a laboratory module related to filters. With this laboratory platform it was accomplish a comparative study between current feedback (CFA) and voltage feedback (VFA). Because the laboratory platform has an educational role, it was presented some practical aspects of active filters measurement and also the differences between the measured values...
This paper proposes a Posicast controller for an inductive power transfer system. First, a modeling of the uncontrolled system is derived. Next, a Posicast-based controller is designed and implemented to improve the dynamic responses of the output voltage for the inductive power transfer system. A rated 1.8kW, 220V DC input, 144V DC output inductive power transfer system is implemented. A detailed...
The transmission line grounding device is an important electrical equipment to avoid accidents of lightning. A new type intelligent detection system of transmission line grounding device is designed for the transmission line and tower of multi-lead line grounding, the detection method of transmission line integrated grounding devices and the fault identification method are proposed, and the practical...
Heat transfer phenomena in electronic nanostructures are supposed not to obey the classic Fourier heat transfer theory. Thus, in order to verify this hypothesis experimentally, a set of MEMS nanostructures was designed and manufactured. These structures contain a number of cavities filled with different materials, including various dielectrics, such as silicon dioxide and the silicon nitride, or air...
Shields generally solve EMC problems due to their high efficiency. When it comes to an electrical automotive drive system, the relatively small quantities of a non ideal shield are of importance due to the high level of emissions generated which face very stringent requirements for low level emissions. As a consequence, the shield and ground loop currents are decisive for various EMC conducted and...
The problem of ensuring the effective functioning of the measuring data acquisition system of RLC-parameters for non-electric objects such as the objects of an environment, food industry, agriculture etc. has been actualized. It has been suggested to conduct remote metrological control at the site of analytical unit's exploitation with the use of differential measurement method and code-controlled...
An anomalous magnetism is observed in an ex-situ bilayer of high-temperature superconductor YBa2Cu3O7-δ and colossal magnetoresistive material La0.67Ca0.33MnO3. The magnetism results in strong in-plane anisotropy of the resistance and surprising peak in the temperature dependence of resistance below superconducting transition associated with the interplay between superconductivity and establishment...
Modern systems of traditional and alternative energy, transport systems include powerful uninterruptible power supplies (UPS), implemented on batteries of charged electrochemical current sources — accumulators. These modules ensure the functioning of the systems in case of accidents or technological failures in the operation of main power supplies. The ability to provide the given energy modes by...
In order to assess the microshock risk, the automatic detection of currents during surgery is important. To this aim, a prototype, called Protegemed, was designed. In order to introduce the device in Italian operating rooms the compliance assessment with international standards is essential. The results of some electrical safety tests and the identification of a measuring method to detect the microshock...
Modulation method and the device for thermal impedance measuring of power COB LEDs and measurement results are described. The measurements were performed by generic modulation method that implies heating a device under test by power varying harmonically. A pulse sequence of heating current, with the pulse length varying harmonically, is passed through the device under test. The p-n junction temperature...
The electrical conductivity of a carbon fiber reinforced plastic (CFRP) panel is highly anisotropic due to its varied fiber orientations. This paper presents an effective modeling method for studying the lightning direct effect on a multidirectional CFRP panel based on an electrical conductivity characterization of unidirectional samples. The characterization using 4-probe method is done with a simple...
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