Lightning current test on radar system

With the extended use of very sensitive electronic components, in modern systems, the danger represented by a lightning stroke becomes something not to be neglected. The Long Range Radar requires protection not only against direct strike, but also against the indirect effects. The formulation of the military standard MIL-STD-464A Severe Strike confirms this need. The peak currents of the discharges are between 50 and 200 kA, for the A pulse, 2 kA for the B pulse and 200 to 800 Amps for the C pulse. For a radar system placed high on a ship, the chosen approach is the fictitious Rolling Sphere Technique in order to confirm the protection offered by the design. Experiments have been carried out using a test setup that could duplicate the three discharge components

Using transfer ratio to evaluate EMC design of adjustable speed drive systems

This paper proposes a way to evaluate the conducted electromagnetic compatibility performance of variable speed drive systems. It is considered that the measured noise level is determined by two factors, the level of the noise source and the conversion efficiency of the propagation path from the source to the measurement equipments. They are corresponding to the two roles played by the converter. On the one hand, a converter provides the noise source and generates the noise current and voltage on the motor side with the cable and the motor. On the other hand, it acts as the propagation path with the DC bus and the rectifier to spread the noise generated on the motor side to the line side. The transfer ratio is defined as the ratio between the CM current on the motor side and the CM current on the line side. It can be used to evaluate the EMC design of a converter because it is independent of the cable and the motor. A simplified model is used to explain this characteristic. It can be measured when the converter is powered off. Verification is carried out by experimental results obtained from a 12-kVA laboratory system.\u

Performance optimization aspects of common mode chokes

Optimization aspects of common mode chokes are presented. These are based on a behavioral model for common mode chokes and its sensitivity study. Results are used to show the influence of the designable parameters on the final performance of the choke placed in a circuit

The effect of inrush transients on pv inverter's grid impedance measurement based on inter-harmonic injection

This paper addresses a cause for false tripping of photovoltaic inverters with antiislanding protection based on impedance measurement with inter-harmonic injection. Earlier discussions about tripping problems happening when several devices are doing the measurement at the same time are supplemented with a problem caused by inrush transients of nearby devices. A series of experiments was conducted in the Power Quality laboratory of the TU/e, on a PV inverter which complies with the DIN VDE 0126 standard. Impedance measurement was done in parallel with the inverter and measurement results are presented. A criterion for false tripping caused by transients is explored. Also, influences of network impedance and grid harmonic pollution on false tripping were analyzed. In the end, some signal processing techniques are proposed to avoid this problem

Model comportemental pour l`evaluation des performances de chokes de mode commun

Un model comportemental pour l’évaluation des performances de choke de mode commun (CMC) est proposé : la topologie et les méthodes utilisés pour modéliser les différentes propriétés de la CMC sont décrites. Il s’agit de la combinaison d’une modélisation précise de la perméabilité complexe du matériau, de la saturation, des inductances de fuite et des capacités parasites. Les données necessaries fournies par le designer sont les valeurs de courants, tensions et impédances du système actuel sans CMC et des paramètres disponibles dans la littérature et /ou des manufacturiers en ce qui concerne la CMC modélisée. Ce model comportemental s’avère essentiel dans la simulation des effets des interférences électromagnétiques (EMI)

Optimization of the in situ Performance of Common Mode Chokes for Power Drive Systems Using Designable Parameters

The selection of electromagnetic interference (EMI) output filters in a power drive system can be a challenge that involves a “cut and try” process with several retro-designed EMI filters, which are often not optimized in term of size, weight, or cost. Key components of an EMI filter are common mode chokes. They are needed to reduce common mode currents which are the main source of radiated emission in power drive systems. Using a “static modification factor,” this paper analyses effects of its designable parameters on its final performance as if it was already in situ. All in situ impedances of the common mode current loop have been taken into account. Two test setups are used to validate effects related to changes of core material, size, number of turns, and wiring system