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In combination with high temperature superconductive (HTS) equipment (e.g. current limiters) or in HTS subnets, which constitute a possible option for increasing the overall efficiency of electrical power distribution systems, only vacuum interrupters can be used directly in the liquid nitrogen environment. This would, however, be desirable for economic reasons. Circuit breakers and switches, respectively,...
Depending on the operating current and the ambient conditions, the operating temperature of vacuum interrupters (VIs) may vary. An increase in VI temperature can result from heat loss at electrical contact resistance points, whereas a significant decrease in temperature will especially occur if VIs are used in future applications in a liquid nitrogen (LN2) environment (e.g. in combination with high-temperature...
Vacuum Interrupters (VIs) rely strongly on the vacuum level to be below 10−2Pa to be able to operate safely. The vacuum status is normally tested during production to be well below this level (typically below 10−5Pa) and then assumed to be sealed for life (fixed at 30 years). With a larger number of vacuum interrupters now reaching their end of life, there is a renewed interest in assessing their...
Switching chambers of vacuum interrupters (VI) are mainly built with ceramics as insulators. During the interruption process, the ceramics are coated by metal vapor from the contact material. In a worst case scenario, an electrical bypass is formed, caused by the metal coating on the ceramic insulators. To avoid this, dielectric shielding is used to provide the vapor coating surfaces with defined...
Due to the impact of arcing on the high purity surfaces and bound residual gases, current interruption operations may influence the internal pressure in vacuum interrupters (VIs). In this paper, we investigate the temporal development of internal pressure in VIs immediately after a current interruption operation, non-intrusively using the magnetron method. By means of an experimental test setup that...
Some vacuum interrupters (VI) are equipped with transversal magnetic field (TMF) contacts. A transversal directed Lorentz force makes the arc move circularly. The local surface temperature of the arc root is usually above the melting point at high current, which can be measured using a high-speed thermography camera. For this purpose, the emissivity of the contact material must be known. For Cu, we...
A simple testing procedure has been developed in order to investigate and screen the current interruption capability of vacuum interrupter contact materials. A synthetic circuit delivering adjustable AC currents, followed by a pulsed of 21 kV peak for 2 seconds has been used. The electrical tests has been developed to reproduce the conditions close to a fault current rated at 12 kV; only the recovery...
The resistance of vacuum interrupters can be calculated from the geometry and resistivity of current carrying parts and the additional resistance of the contact points between movable and fixed contacts. Since vacuum interrupter contacts are designed as flat contacts facing each other, the resistance is mainly determined by contact force, hardness and resistivity of the contact material. It is known...
Different vacuum interrupters (VI) are equipped with Transversal Magnetic Field (TMF) contacts. Due to the current path, a transversal directed Lorentz-force is affecting the electric arc to move in a circular, in order to reduce the heat input and therefore the local erosion of the contact surface. The degree of the contact erosion is dependent on the local temperature of the arc root, which can...
In the coming years an increasing quantity of vacuum interrupters (VI) is expected to reach the end of its service life. Leading manufacturers can provide a service life of up to 30 years due to high quality standards and sophisticated production processes. However, their operating performance observed so far indicates the possibility to extend this service life, in case of non-intrusive diagnosis...
The magnetron method is well established for the internal pressure measurement of vacuum interrupters. Its application during the manufacturing process is essential for the determination of the vacuum quality. The evaluation of the magnetron measurement requires precise knowledge of the residual gas composition and the influence of the metallic surfaces in the vacuum interrupter due to gas binding...
Vacuum interrupters (VI's) are the primary switching technology for medium voltage (1–52kV) electrical power systems. The extensive field service of VI's is now raising interest in determining the end of life for these devices, with the primary concern being the loss of vacuum. The manufacturing method of the VI's can affect the calculated long-term life. In particular, there are three main design...
Vacuum interrupters are serving worldwide in distribution circuits, meeting the electrical and mechanical requirements specified in the IEC and/or ANSI standards for low and medium voltage applications. Generator circuits require special generator circuit-breakers and are tested according to IEC 62271-37.013/ANSI/IEEE C37.013. Traditionally, generator circuit-breakers have been very large devices...
A testing procedure has been developed with the aim to investigate and to screen the current interruption capability of vacuum interrupters with different contact materials. A synthetic circuit delivering a 1.2ms pulse current up to 18 kA was used in order to simulate a surface temperature on the electrodes similar to the constricted arc mode. At current zero a pulse voltage was injected to stress...
A new two-contact system with double-TMF structure is investigated regarding its potential for high current interruption. It consists in two co-axial TMF contacts in which the inner contact has a disk-shape structure (spiral contacts) and an outer contact with cup-shape structure. This contacts assembly gives some advantages over the single-TMF contacts one, as the high current constricted arc might...
This work consists in investigating the vacuum arc behavior during the high current interruption process using a new innovative co-axial double-contact system. The so-called new TMF-AMF contact structure offers the advantage of low total resistance for nominal current conduction as in standard TMF contacts and similar vacuum arc control as in AMF contacts. For an optimized contact's geometry, FEM...
Vacuum Interrupters (VIs) are designed for a long operating life. Even after a large number of switching operations they should still provide good arc extinction and be able to withstand high voltages. Switching operations produce substantial masses of metal vapor that condense on the inner component parts of the VI. The Vis are equipped with shields to protect the ceramic surfaces from being coated...
ABB has over 10 years of experience in the use of embedded pole technology based on epoxy insulation in medium-voltage circuit breakers with vacuum interrupters. The next significant step in this technology is the development of embedded poles that use a thermoplastic material.
Experiments have been conducted to study the influence of the closing speed of the drive mechanism on the performance of vacuum interrupters used for capacitive switching. Given the experimental conditions (no load-opening), it was found that the probability of breakdown is about 30% less with a fast closing speed (contacts closing on average before a half-cycle of the inrush current) compared to...
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