Extinguishing Chamber Research Articles

NEW MECHANISMS FOR THE POWER SWITCHER WITH V EXTINGUISHING CHAMBERS

Starting from an existing V power switcher mechanism, the paper presents two new kinematic schemes of the V switcher mechanisms for medium and high power. The proposed schemes consist of triadic chains that ensure transmission angles near to the optimum values. The geometric and kinematic analyses of the proposed mechanisms, with\ driven components that have to move with high speeds on disengaging process in the extinguishing chamber, have been achieved. In the second section of the paper, an optimum kinematic scheme of the V power switcher with triadic chain type 4R+2T has been presented.

Characteristics of the Arc Voltage of a High‐Current Air Arc in a Sealed Chamber

SUMMARYThe effect of the arc voltage on various factors of design and control was investigated for high currents in order to develop design guidelines for circuit breakers. In this study, the dependence on such factors, namely, the current, arc length, electrode surface area, and internal pressure of the arc voltage, was evaluated quantitatively. As a result of the evaluations, it was estimated that the arc voltage near the electrode surface rises linearly with the arc current and the power −0.8 of the surface area, and that the voltage in the arc column rises as the 0.3 power of the pressure increase. We confirmed the validity of the estimated voltage characteristics by comparison with the generated voltage in an actual arc‐extinction chamber. The characteristics of the estimated voltage can provide effective guidelines for the design of arc extinguishing chambers. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 34–42, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22487

Characteristics of Arc Voltage for High-Current Air Arc under Arrangement of Deion Plates and Approach to Improving Availability of the Plates

In this study, (i) effect of deion plates on arc voltage and (ii) appropriate arrangement of the plates were investigated in order to develop a design guide of a circuit breaker which is able to interrupt fault current (> several kA). As for evaluation (i), improved effect on arc voltage under arrangement of the plates were evaluated quantitatively in association between arc voltage and the design factors which are current, arc length, internal pressure and number of the used plates. As the result, it was found that arc voltage rises 19.2V by number of split arc between the plates and electrical field in arc rises about 3V/mm under high internal pressure above 0.2MPa-g. Experimental formula constituted by the design factors for estimation of arc voltage was developed on the basis of the improved effect on the voltage. Since the formula is able to estimate actual arc voltage with a margin of error within about 7%, it would be provided as effective guidelines to design arc extinguishing chambers. As for evaluation (ii), dependences of the availability of used plates on electromagnetic force to drive arc were evaluated. As the result, it is found that the plates are used effectively by exerting above a certain electromagnetic force (e. g., above 5N in case of 5kA) on the arc between the electrode and the plate. Therefore, the improvement of magnetic design near the electrodes, especially the movable electrode, or the arranging enough space to drive the arc between the electrode and the plate would be improved availability of the used plates.

Characteristics of Arc Voltage of High-Current Air Arc in Sealed Chamber

Effect of arc voltage on different factor of design and control was investigated for high current in order to develop design guide of circuit breaker. In this study, dependences on these factors which are current, arc length, surface area on electrode and internal pressure of arc voltage were evaluated quantitatively. As a result of the evaluations, it was estimated that arc voltage near electrode surface rise linearly with arc current and the area on the surface to the power -0.8, and the voltage in arc column rise pressure increase to the power 0.3. We confirmed the validity of the characteristics of the estimated voltage by comparison with the generated voltage in an actual arc extinguishing chamber. The characteristics of the estimated voltage would be provided as effective guidelines to design arc extinguishing chambers.

Effect of Internal Electrical Field on the Electrical Breakdown Properties of Contact Materials

In order to get a deep understanding of the effect of internal electrical field on the electrical breakdown properties of contact materials, two kinds of W-Cu and Cr-Cu joints were prepared in a vacuum sintering furnace. The vacuum breakdown tests were respectively performed at the interface of two joints and pure metal ends in an arc extinguishing chamber, and the surface morphologies after electrical breakdown 50 times were characterized by a scanning electron microscopy equipped with an energy dispersive spectroscopy. The results show that the breakdown strength at the interface is much larger than that of pure metal ends, and the breakdown site deviates from the interface. It is suggested that the existence of internal electrical field at the interface of two contact metals changes the electronic structure, and, thus, the electrical breakdown behavior is influenced.

Probabilistic model and contacts reliability estimation method of electromagnetic AC contactors

AbstractIn the paper a probabilistic reliability model of contacts used in low voltage AC electromagnetic contactors is presented along with the theoretical foundation of the contacts reliability estimation method which employs resulrs of the simplified conracts durability tests. The model is derived from the analysis ofphysical and chem‐ ical processes which are observed during contactor operation and may result in contacts failure. The clue of the model is the mathematical description of the contacts wear allowance deterioration which is considered as the forecasting parameter of contacts durability. The model presented appears to be more adequate and accurate than the other ones which are used for description of contacts wear‐off mechanisms. Both the model and the method proposed can be applied in analysis of influence of material and design parameters on contacts durability, in design of new contacts and arc extinguishing chambers and, first of all, in the development of new and fast durability tests which can be applied by contactor manufacturers and users.

4678726 Multicell electric storage battery with combined means for wastegas drying and flame-protection

In a multicell electric storage battery designed for central gas release, before being released into the open air the battery gases pass through a container positioned on the block casing in which the acid particles and moisture are separated from the gases as a consequence of the gases being repeatedly deflected by a series of walls placed in the path of the gases, which may be perforated if desired, and the dehumidified gases are then passed through a porous flame-protection frit. Flashback of a flame caused by external ignition of the gases is prevented by rapid burn-off of the gases in a flame extinguishing chamber preceding the frit.