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The circuit breaker
Abstract
ABB Review traces the development of circuit breakers, an indispensable part of the electrical grid, highlighting the contributions made by ABB and its predecessor companies. Circuit breakers are needed in electricity generators, where the full power of an entire power plant is required to be switched on and off, and on transmission lines in substations to direct the power flow at voltage in excess of 1500 kV. Circuit breakers are also critical components in distribution grids, where very high currents is required to be managed at moderate voltage levels. The power management of the electric arc in all the existing circuit breakers is used for the prevention of arc formation if a new switching principle using power semi-conductors could be devised. Semiconductor technology would allow a power circuit breaker to be designed, but the system requires to be highly complex and extremely costly exercise. Circuit breaker is applied in the high-voltage, direct-current (HVDC) systems.
... HIGH voltage gas circuit breakers are the key safety devices in electric power systems and have to separate faulty parts of the grid quickly and reliably. The interruption capability of high voltage circuit breakers have been increased over the last decades and today, SF 6 insulated circuit breakers are capable of switching up to 20 GVA per interrupting unit [1]. ...
In the past few years gas insulated high voltage circuit breakers have improved considerably, in particular with respect to required drive energy for operation, compactness and reliability. A further reduction in size implies increasing operational field stress inside the breaker and, thus, a reduction in built-in safety margins. If the design comes closer to its physical limits, in particular the dielectric coordination of the contact systems becomes more and more challenging. The aim of the present work is to identify factors that may influence the dielectric coordination of contact systems with reduced coordination margin. The breakdown probability distribution of SF6 insulated multi-contact systems was investigated with the focus on two aspects. First of all, the breakdown probabilities under lightning impulse (LI) stress were measured. These indicated that it is not feasible to extrapolate the breakdown probability curves of single contacts to a combined full contact system. Secondly, the findings on the same contact system stressed with very fast transient voltages (VFT) showed a considerable reduction in breakdown voltage and suggested a significant increase in the main contact breakdown probability, compared to the LI tests. The results and interpretation within this work indentified the polarity and voltage shape dependent breakdown initiation of different contacts as causes for circuit breaker contact system failure.
... Using the minimum oil circuit breaker (Min oil) as an example [6], the result is obtained by multiplying the corresponding factors which are then summed together to get the total score. The cost relative score of breaker is multiplied by the percentage of user preference weight, and the same applies to the other three aspects. ...
This paper presents a broader analysis approach which adds to the traditional fault analysis technique commonly used in industry to size and select circuit breakers required for the power system. The fault analysis has been simulated on a computer software program DIgSILENT PowerFactory for all fault conditions. The circuit breaker selection will be based on a Multi-Criteria Analysis which helps to evaluate the design to arrive at the most user preferred result. This approach is refined to incorporate user preferences with respect to the criteria so that the final design is representative of both the design specification and the concerns of the user. This broader newer approach has been shown by means of case studies to be effective.
... HIGH voltage gas circuit breakers are the key safety devices in electric power systems and have to separate faulty parts of the grid quickly and reliably. The interruption capability of high voltage circuit breakers have been increased over the last decades and today, SF 6 insulated circuit breakers are capable of switching up to 20 GVA per interrupting unit [1]. ...
Various studies have been carried out to determine the origin, the development and the effects of very fast transients (VFT) in GIS-Busbars. To date little knowledge exists on how VFT propagate through a high voltage circuit breaker, when the interrupter itself is the source of the VFT. For the development of circuit breakers it is important to know if these VFT are able to affect the dielectric coordination of the interrupter. In order to determine transient voltages at different locations inside an interrupter unit a numerical model has been derived. The model approach represents the circuit breaker as a system of concatenated transmission lines. The simulations were compared to measurements of a real circuit breaker and prooved the accuracy of the model in the frequency range from 9 kHz up to 500 MHz. This model allows future parameter studies which show the dependence of VFT overvoltages on the geometry of the circuit breaker.
This paper describes the advantages of using data acquisition systems and software modelling tools to support the assessment and therefore redesign of the existing medium voltage switchgear. A 38kV/630A load break linear puffer (LP) will be used as an example for this study. In house testing was conducted to capture important design parameters of the switch such as displacement, velocity of mechanical parts and gas pressure using various sensors and three different measurement setups. The first setup, which is primarily intended for no-load measurements, consists of a DAQ system equipped with different types of sensors - two rotational encoders, three laser-based distance sensors, six pressure sensors, contact separation measurement, and a high-speed camera integrated and synchronized with the measurement system. The second and third setups, which are suitable both for no-load and on-load measurements, are based on state-of-the-art DAQ systems, which use three piezo-electric based pressure sensors, two fibre-optic based pressure sensors, three laser-based distance sensors and a high speed camera synchronized with the measurement system. The data acquired by the measurement systems is used in combination with an in-house developed simulation software HV CB Simulation, which enables simulating and predicting various variables of switching devices. Moreover, high speed camera videos analysed with both commercial and in-house developed image processing software, visualize and reveal many otherwise inaccessible occurrences. In addition to a comprehensive analysis of the proposed data acquisition and simulation setups, three design improvements in the linear puffer design - increase of the opening speed, removal of the flexible conductors and the length increase of the puffer cylinder - are presented and discussed in this paper.
This paper presents a bibliography of HVDC transmission technology for 2006-07. It provides a listing of various journal and conference papers in this area.
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