Frank Berger

Technische Universität Ilmenau | TUI · Institut für Elektrische Energie- und Steuerungstechnik

An assessment for the safe use of electrical equipment in explosive atmospheres can be performed with the aid of a spark test apparatus. Therefore, an anodic tungsten wire with 200 µm diameter is moved along the surface of a rotating cadmium disc (cathode). The explosion chamber enclosing the electrodes is filled with a highly explosive mixture of...

Contact break discharges generated by electrical equipment in potentially explosive atmospheres are typically obtained at low voltages below 30 V and low currents between 30 mA and 100 mA are a relevant ignition source. The electrical characteristics of these discharges, which are dominated by metal vapor, have been presented in previous works. How...

Partial discharges cause noise. Corona, arcing and tracking are typical discharge effects. Commonly, they are accompanied by characteristic acoustic emissions. This noise can used in maintenance for monitoring the operation and/or safety of electrical equipment. The objective of acoustic condition monitoring is to detect the presence of faulty even...

Under DC voltage stress dielectric liquids reveal a non-linear electrical conductivity, which cannot be sufficiently modelled with conventional RC equivalent circuit diagrams. Rather, a comprehensive chemical-physical understanding of charge generation and transport processes is required to describe the electrical conductivity of liquid dielectrics...

This contribution is focused on a new calculation method of the breakdown voltage i.e. the dielectric strength of gases in dependence of pressure, distance and arbitrary electrode and electric field arrangement, within the weakly inhomogeneous electric field. This breakdown voltage calculation is based on the well-known criterion according Townsend...

The presented work focuses on the effects of the changeover from AC to DC technology for high voltage bushings as indicated weak points of HVDC. This transition is investigated on a 170 kV polymeric insulated bushing by means of AC and DC analysis, including very low frequencies. On this kind of bushing, biaxially-oriented polyester film layers are...

Schwefelhexafluorid (SF6) ist das zurzeit noch meist verwendete Isoliergas der Hochspannungstechnik. Neben den exzellenten Isoliereigenschaften besitzt SF6 das höchste Treibhauspotential aller bekannten Gase, (23800_CO2 [10]). Aus diesem Grund ist die Verwendung von SF6 stark limitiert. Der Bedarf SF6 zu ersetzen steigt, [7], [3]. Dieser Beitrag is...

In order to investigate the long-term behavior of contact resistance in low-voltage contactors under the influence of electric arcs in polymer housings, a new model switch was developed. The model switch permits the modification of different factors such as contact gap, contact force, closing and/or separation speed of the contacts, and arc-chamber...

The thermo-mechanical damage of a structure near the lightning attachment point is caused by the direct heat flux from the hot plasma channel at the arc root, the Joule heat generated by impressed lightning electric current, and finally by the thermal heat radiation from the hot lightning plasma channel. For an accurate estimation of the degree of...

Various fault scenarios have been analyzed by running a number of differently combined 380 VDC microgrid tests.These tests represented a common grid topology with low systemimpedance at grid resonance points within the single- or lowerdouble-digit kHz range. At serial arc faults, self-excited resonantmodes of the arc plasma column have been observe...

The aim of this paper is to present a further approach for analyzing the air electric arc in low-voltage circuit breakers (LVCBs). In order to achieve that, a new simulation model and experimental tests have been carried out. The simulation model has been designed using ANSYS CFX, a finite-volume method commercial software. This model has been defi...

as a first step in a long-term planned cooperation between the TU Ilmenau and several industry partners a model switch was developed and constructed in order to investigate the influence of different aspects affecting the evolution of contact resistance during the lifetime of electrical contacts in low voltage contactors. The device permits, beside...

Contrary to other test setups, a virtually unmodified contactor actuator has been integrated into a model switch to reproduce contact bouncing of make operations. This allows for a less complex machine than an electro mechanical or pneumatic replica of the original actuator. Furthermore optical and mechanical access to the contacts is significantly...

The use of renewable energy is a key topic in the global energy market. Wind parks are being built all over the world, especially offshore, and large hydroelectric power stations are producing enormous amounts of electrical energy. Yet, the regions abounding in renewable energy frequently do not coincide with the consumption sites of energy. Theref...

Sulphur hexafluoride (SF6) is the most common insulation gas in high voltage technology because of the electron attachment (electron affinity) SF6 has the three times higher dielectric strength at 0.1 MPa compared to air. Beside this SF6 has the most known global warming potential (GWP) and there is demand on alternative insulation gases. SF6 has a...

Modellbildung und Simulation sind wichtige Elemente u.a. bei der Entwicklung von Schaltgeräten, beim Studium des Lichtbogenverhaltens oder des Verhaltens elektrischer Kontakte im praktischen Einsatz. Die Nachbildung der im Schaltbetrieb auftretenden physikalischen Vorgänge erfolgt durch Modelle, die Rückschlüsse auf das Verhalten im realen Schaltge...

Die Aufgaben, Beanspruchungen und Bauweisen der in der Hoch- und Mittelspannungstechnik eingesetzten Schalter sind außerordentlich mannigfaltig. Es ist deshalb notwendig, sie nach mehreren Kriterien zu kennzeichnen, insbesondere hinsichtlich

In elektrischen Industrieanlagen, Hausinstallationen oder Bordnetzen können beim Auftreten eines Fehlers Lichtbögen entstehen, die als Störlichtbögen bezeichnet werden. Für deren Entstehung gibt es vielfältige Ursachen, z.B. fehlerhafte Verbindungen, Isolationsfehler, Montage- und Materialfehler, Alterungserscheinungen am Kontaktsystem, Korrosion o...

Die Entwicklung des weltweiten Verbrauchs an Primärenergie (Kohle, Erdgas, Erdöl, Gas, Holz) hat sich in den letzten 40 Jahren mehr als verdoppelt. Der Grund für diesen Anstieg liegt u. a. in einer wachsenden Weltbevölkerung und einem steigenden Pro-Kopf-Verbrauch an Elektroenergie. Darüber hinaus müssen Probleme, wie die Verknappung der natürliche...

The paper presents a new model switch for the investigation of the different aspects of switching arcs as well as their interaction with the involved parts of switching devices in low voltage appliances. The constructed model was designed to accomplish experimental series according to IEC 60947. Focusing as a first approach on the investigation of...

Sulphur hexafluoride (SF 6) is the most common insulation gas in high voltage technology. Besides the excellent insulation properties SF 6 has the most known global warming potential with a long lifetime in the atmosphere. Alternative insulation gases have only a fraction of the insulation level of SF 6. The electric strength of gases depends on th...

For the investigation of the interaction between low-voltage switching arcs the contacts and the surrounding switching chamber materials a model switch has been constructed. The model switch enables to perform test series in standard categories like IEC 60947 (AC-4 / DC-5) for currents up to 500 A. Due to the flexible design, it is possible to chan...

Für die konstruktive Auslegung von individuellen Steckverbinderkontakten sind skalierbare Baureihen, angepasste Gebrauchseigenschaften und eine grenzwertige Auslegungen wünschenswert. Um diesen Herausforderungen zu begegnen, wird im Rahmen dieser Studie ein systematisches Vorgehen zur konstruktiven Auslegung von Steckverbinderkontakten für die Leis...

Sulphur hexafluoride (SF 6) is the most common insulation gas in high voltage technology. Besides the excellent insulation properties SF 6 has the most known global warming potential. Alternative insulation gases have only a fraction of the insulation level of SF 6. The electric strength of gases depends on the gas density and can be increased sign...

Sulphur hexafluoride (SF6) is the most common insulation gas in high voltage technology. Besides the excellent insulation properties SF6 has the most known global warming potential with a long lifetime in the atmosphere. Alternative insulation gases have only a fraction of the insulation level of SF6. The electric strength of gases depends on the g...

Sulphur hexafluoride (SF6) is the most common insulation gas in high voltage technology. Besides the excellent insulation properties SF6 has the most known global warming potential with a long lifetime in the atmosphere. Alternative insulation gases have only a fraction of the insulation level of SF6. The electric strength of gases depends on the g...

Die Erwärmung von elektrischen Bauteilen wird durch Wärmeerzeugung in Form von Joule ́scher Wärme und Wärmeabfuhr in Form von Konvektion, Strahlung und Wärmeleitung bestimmt. Für die Berechnung und Optimierung der thermischen Gebrauchseigenschaften von Steckverbinderkontakten ist die separate Betrachtung der einzelnen Wärmeabfuhrmechanismen sehr wi...

The continuous growing requirements on power relays make it necessary to handle higher switching capacities which are represented in an increasing number of switching operations resulting in a demand for an extended lifetime of the relays. Especially by switching direct currents a directed material transfer which is limiting the lifetime can occur....

The electrical-thermal behavior of an electrical connector is determined by heat generation due to Joule heating and heat absorption by conduction, convection and radiation. Heat flow from the connector to the wire is an important heat absorption mechanism for most electrical connectors. The temperature difference between the connector and the wire...

Experiments with arcs confined in tubes and Miniature Circuit Breakers-MCBs with gassing walls of different engineering plastic compounds were carried out. In the first part of the investigation the arc chamber consisted of small tubes of the different materials. The arc-current source was a damped capacity bank with high charging voltages. For the...

DC arcing faults pose a safety risk in already existing photovoltaic systems. Due to the aging of the photovoltaic system components enhanced by environmental factors and the high DC voltages, long-lasting arc faults can occur and may cause serious damage. Conventional fault protection methods - like circuit breakers or fuses - are only able to cle...

In many electrical connectors multiple contact springs design is used in order to increase the stability and reliability of the contacts. By increasing the number of contact springs the number of contact points also increases and the total electrical contact resistance decreases. For a given width of the connector, the increasing number of contact...

Pressboard is one of the key components in insulation systems for HVDC (high voltage direct current) equipment. The conductivity of pressboard is one of the most important properties of these systems. It is dependent on various parameters, e. g. time, temperature, electrical field strength, water content and impregnating fluid, which are varied in...

Iron and manganese are relevant constituents of the earth's crust and both show increasing mobility when reduced by free electrons. This reduction is known to be controlled by microbial dissimilation processes. Alternative sources of free electrons in nature are cloud-to-ground lightning events with thermal and galvanic effects. Where thermal effec...

The current carrying capacity, which is determined by the electrical-thermal behaviour, is one of the main features of an electrical contact system. The purpose of this study is to develop an analytical model which describes the electrical- thermal behaviour of electrical contact systems. Established mechanical, electrical, thermal and contact phys...

Electric arcs in electrical DC systems represent both an enormous challenge to switchgear (switch arc) and a serious hazard to humans and the whole system (fault arc). Hitherto existing literature states an negative impact of a parallel capacitance on the arc existence. For low voltage DC systems the behavior of free burning arcs in air is analyzed...

Experiments with high current arcs confined in gassing polymer walls for two different experimental setups and characteristics of the current source were carried out. The first setup consists of a rotationally symmetric electrode configuration with the arc burning inside a small polymer tube. For the second setup conventional 16 A miniature circuit...

Low voltage circuit breakers in modern AC and DC networks should be capable of cut off operational as well as fault currents. An important influence factor for a successful current interruption is determined by the arc-attachment at the electrodes, supporting or limiting a quick arc-movement to the running-rails and towards the extinction chamber....

Arc faults pose an extreme safety risk in already existing photovoltaic systems. In comparison to AC installations arc faults in photovoltaic systems have a significantly higher hazard potential. Missing zero-crossings of the current and the fact that a solar generator regarded as a source of energy cannot be switched off ensure much better conditi...

Die Stromtragfähigkeit von Kontaktsystemen mit zwei Kontaktfedern wird analytisch berechnet. Hierzu werden die bekannten mechanischen, elektrischen, thermischen und kontaktphysikalischen Teilmodelle verwendet und miteinander verknüpft. An dem aufgestellten Modell wird der Parameter elektrische Leitfähigkeit variiert und dessen Einfluss auf die Erwä...

Arc oscillations with current crossing zero are essential for arc extinction in both AC and DC networks. These oscillations are always dynamic processes. In the case of AC arcs oscillations are given by the network causing periodic zero crossings of the arc current. For DC arcs current has to be forced to cross zero by appropriate measures. DC elec...

Directional material transfer mainly occurs at direct current applications of low load switches (1 - 100 V and 0.01 -50 A). Non-opening due to mechanical interlocking or bridging may occur by forming material transfer pips and craters. Investigations revealed (1) the shape of pip and crater and (2) the relative motion between contact pieces as majo...

Diagnosis and ageing-condition assessment of electrical equipment are getting more and more important, as many of the units in use are close to the end of their designed service life or have even exceeded it already. There are several tools for diagnosis which are well known and proven for transformer monitoring and assessment. In principle, the sa...

The main focus of this work is to give an overview of the mathematical errors introduced by the spatial discretization in case of plasma simulations. Two standard models for the electric arc simulation have been used; a Free Burning Arc (FBA) and a Switching Arc (SA). Three radiation models have been studied for each arc model in order to verify ho...

The main focus of this work is to give an overview of the mathematical errors introduced by the temporal and spatial discretization in case of plasma simulations. Two standard models for the electric arc simulation have been used, for each of them a variation of the timestep and of the mesh density has been performed. Furthermore, three radiation m...

This paper deals with the experimental verification of the current carrying capacity of soft-solder joints of metal elements of titanium zinc used for roof drainage systems. The possible consequences of the flow of a lightning current through a soft solder joint were first analysed from a theoretical point of view. The current carrying capacity of...

Gassing polymer walls are used in circuit breakers to improve their interrupting and current limiting performance. The energy of the arc will be partially absorbed by the polymer walls, causing chemical degradation and evaporation. The evaporated gas reaches the arc plasma changing its composition and influencing its burning conditions. The resulti...

Kurzfassung Stromkreise in der Niederspannungs-Elektroinstallation werden üblicherweise mit Sicherungen, Leitungs-schutzschaltern und Fehlerstromschutzschaltern geschützt. Bei Störlichtbogenfehlern bieten diese Schutzgeräte jedoch keinen ausreichenden Schutz. Störlichtbogen-Erfassungseinrichtungen (AFDD: Arc Fault Detection Device) sind schon in No...

Currently there is technology capable of detecting arcing conditions in low voltage installations available in the United States and Canada (120 V, 60 Hz). This technology has been developed to increase the protection of those installations against electrical fires. While there is a great interest to apply this technology to higher voltage applicat...

Material transfer in a low-power direct-current switchgear is commonly known to cause contact failures to open due to mechanical interlocking, which is determined by (i) the shape of the material transfer pip-and-crater formation and (ii) the relative movement of the contact pieces during contact separation. The aim of this work is to analyze the i...

The behavior of DC-arcs on Ag-composites (Ag/SnO2 and Ag/SnO2/In2O3) and on Ag was investigated using a parallel rail setup. A high speed CCD-Camera (sampling rates of up to 40000 fps) was used to observe the appearance of the arc at the electrodes and its motion characteristics. Previously, the rails were polished up to 0.25 μm grain in order to a...

Short-circuits in electrical networks imply extreme mechanical and thermal stresses to loads, systems, and protection devices. The paper discusses new approaches for low-voltage system protection. The three-dimensional locus curves criterion will be pointed out as one opportunity for short-circuit detection. Regression analysis, used to predict the...

This paper deals with the simulation of the energy transport due to radiation in air plasma flows. The numerical investigation of the plasma is based on magneto-hydrodynamic (MHD) equations which are solved using the commercial CFD package Fluent. Different radiation models, a P-1 radiation model, a discrete ordinates model and a model based on the...

Short-circuits in electrical networks come along with severe mechanical and thermal stresses not only to loads and systems, but also to the installed protection devices. Combined analytical simulations have been performed for analyzing and optimizing the behavior of low-voltage circuit-breakers. Especially circuit-breakers with electronic tripping...

Context data is a main feature inside mobile field processes (e.g. maintenance, repair, manufacturing). The demonstrator describes the usage of a context engine inside the software platform NoFiS^#, which receives, handles and adapts location context to the maintenance process of aircrafts.

This paper deals with the simulation of the energy transport due to radiation in air plasma flows. In the simulations, a thermal plasma in local thermodynamic equilibrium according to a fifteen species air model is assumed. Different radiation models, a grey P - 1 radiation model, a non-grey P - 1 radiation model and a non-grey Discrete Ordinate ra...

The first part of the paper deals with the experimental investigation of the arc behaviour in quenching chambers of low-voltage devices with different splitter plate arrangements. Besides the measurement of the electrical quantities current and arc voltage, the pressure was recorded at different positions in the chamber wall. For the characterisati...

New technologies and algorithms for an electronic short-circuit detection in low-voltage switchgears aiming for improvements in current limitation will be presented. For early short-circuit detection, the new "Cubical-Criterion" has been invented. The criterion uses the instantaneous values of current, current rise and current's 2^nd deri...

Arcs of lightning continuing currents with sufficiently high currents and long durations perforate thin metal sheets. Limiting curves of perforation resistance for commonly used metals and thicknesses were experimentally determined. Axial forces, occurring on the arc root of high pulse current arcs, were measured as well as calculated. Pulse curren...

Short-circuit detection times have to be shortened to reduce loss of contact material and improve power line protection. The problems of electronic short-circuit detection for improving current limitation in low-voltage circuit-breakers are discussed. Therefore network and load-analyses have been realized in theory and by power-quality measurement...