Piotr Oramus

Limitation of Electric Arc Energy in LV Switches During Inductive Current Interruption

In this paper, the commutation and switching mechanisms between the operating low-voltage (LV) switch and parallel external branches are presented. Experiments for the limitation of electric arc energy during inductive current interruption were performed for three scenarios: 1) for standalone operated switch (base case), 2) for passive method of arc energy limitation (widely applied RC branch connected in parallel to operated switch), and 3) active method of electric arc energy limitation (current commutation into the external semiconductor branch controlled by the microprocessor system). A typical three-phase electromechanical LV switch with double arc quenching chamber was selected as the tested object. The following parameters were investigated: electric arc resistance, electric arc power, electric arc energy, as well as power and energy generated at the external branch connected in parallel to the operating switch. Measurements were performed for current interruption in a single-phase circuit. In addition, observations of a burning electric arc in the quenching arc chamber were registered by an ultraspeed camera (for two cases: base case and hybrid switching).

Investigation into Limitation of Arc Erosion in LV Switches Through Application of Hybrid Switching

In this paper, measurement results of the arc erosion limitation in low voltage (LV) switches are presented. The reduction of the arc erosion in the analyzed electromechanical switches was achieved through an application of the hybrid switching in the tested alternative current circuit during interruption of the inductive current. The presented method is based on a commutation of the current during its interruption into a semiconductor branch that is connected in parallel to the operated switch. Thus, this approach is able to limit the electric arc energy efficiently, and as a consequence the arc erosion of the electrical contacts is also significantly reduced. For this reason, the application of the hybrid switching has a positive influence on a lifespan and a reliability of the operated switch. In order to evaluate the influence of the hybrid switching application on an effectiveness of the limitation of the arc erosion in the analyzed LV switches, 50 000 current interruptions were conducted in the tested circuit by each of four analyzed switches. Researches were performed for two standalone switches during a standard current interruption, as well as, for two switches with applied the hybrid switching system. In order to compare the arc erosion of the contact surfaces in both considered cases, scanning electron microscope method coupled with energy dispersion spectroscopy was applied. Moreover, photos of the electric contact surfaces are presented. Additionally, frames registered by high-speed camera during current interruption are presented for both considered approaches.

Simulations of electric arc behavior in hybrid LV switches

In this paper the commutation mechanism based on LV mechanical circuit breaker and parallel semiconductor device is discussed. This hybrid switch comprises electromechanical relay connected in parallel with semiconductor branch controlled by microprocessor unit. The work presented herein covers both laboratory experiments as well as EMTP-ATP simulations, where modeling of electric arc behavior was based on Cassie-Mayr black-box model with accordingly estimated parameters. Such analyses are especially important in case of hybrid switching systems due to possibility of estimating system response during transient conditions (overvoltages, current distribution, power and energy dissipated at semiconductor branch, power and energy of electric arc, etc.). Presented model provides satisfactory convergence of simulation results with data obtained during experiments.

Modeling of Repetitive Ignitions in Switching Devices: Case Studies on Vacuum Circuit Breaker and GIS Disconnector

Repetitive ignitions of electric arc during switching operation may result in generating Fast and Very Fast Transients (FT and VFT) and thus require analyses to ensure reliable system operation. The paper presents a common approach for modeling and simulation of such phenomenon for two types of switching devices: Vacuum Circuit Breakers (VCB) and GIS disconnectors. In each case, the associated (VFT) are modeled with the use of a case-specific Breakdown Voltage Characteristic (BDV), characterizing the switching process, and with the use of case-specific power system conditions. Two case studies are presented. For Vacuum Circuit Breaker, a switching operation of un-loaded transformer is presented. For GIS disconnector, switching of short bus-bar during the disconnector type testing is presented.

Application of bidirectional transient voltage suppressor for electric arc suppression in LV switches - simulation and laboratory case study

This paper presents the analysis of bidirectional Transient Voltage Suppressor (TVS) application for limitation of the electric arc energy in a low voltage circuit. The study employs both simulations and laboratory experiments, which were conducted to present inductive current breaking procedure with use of a standard switch and a switch with passive arc suppressor connected in parallel. EMTP-ATP simulations, where modeling of electric arc behavior was based on Cassie-Mayr black-box model with accordingly estimated parameters, provided satisfactory convergence with data obtained during experiments. Therefore, it can be concluded that in this case, the simulation is an accurate representation of physical nature of the analyzed switching process. Hence, developed computer model can be used to analyze switching overvoltages, current distribution, power and energy dissipated at semiconductor branch, as well as, power and energy of electric arc.

Modelowanie łuku elektrycznego w analizach przepięć łączeniowych podczas przerywania prądu przy użyciu niskonapięciowych styczników elektromechanicznych

This paper presents the electric arc modelling and its implementation in specialized simulation software for transient analyses during switching conditions in LV circuits (EMTP-ATP software). Simulations can be very useful to estimate overvoltages and arcing times during switching operations performed by means of electromechanical relays, which are commonly used in automation. Comparison of measured and calculated Transient Recovery Voltage (TRV) and current waveforms is shown in this article. It is clearly indicated that severe overvoltages may arise upon electromechanical relays operation, and that the simulation is an efficient tool when analyzing such phenomena. (Modeling of electric arc in analysis of switching overvoltages during current interruption with LV electromechanical relays). Słowa kluczowe: model Mayra, łuk elektryczny, stycznik, przepięcia