CN1894762B - Switchgear for medium-voltage range and high-voltage range - Google Patents

Abstract

The invention relates to a switchgear for the medium-voltage range and the high-voltage range, comprising power switches and/or load interrupter switches, according to patent claim 1. The aim of the invention is to better ensure the inverse ignition freedom and to achieve the effective division of the voltage in the switching process. To this end, two switches (1) are mounted in series on each phase, which can be controlled in such a way that they are co-ordinated with each other in a small window of time (dt).

Description

Switchgear for medium and high voltage ranges

technical field

The invention relates to a switching device for the medium voltage range and the high voltage range. the

This technical field relates to medium voltage switchgear, but does not exclude high voltage switchgear, in particular vacuum circuit breakers suitable for frequent switching of capacitor banks. the

Background technique

SF ₆ -filled circuit breakers and vacuum circuit breakers, which can break short-circuit currents in addition to capacitive currents, or special capacitor switching devices which can only handle capacitive currents, are known. High recovery voltages occur when the capacitor charging current is interrupted in the power supply system and inherently hides the danger of arc reignition across the switching gap. The resulting overvoltage can destroy capacitors or the power supply system. IEC 62271-100, which has been in effect since 2001, considers the possibility of the above occurrence to a greater extent than before, classifying circuit breakers on the basis of low probability and very low probability of arc restrike. Arc reignition may not occur at all in a corresponding type of test. This leads to stringent requirements on the characteristics of the circuit breaker.

At higher voltages, in this case mainly 36KV and higher supply levels, it becomes more difficult to ensure that arc reignition does not occur. This is due to the fact that the vacuum switching principle itself involves a fundamental dependence of the contact spacing on the dielectric strength of the arrangement. Therefore, higher voltage breakdown can only be obtained by over-proportionally increasing the contact spacing. In addition, the random nature of vacuum breakdown is another factor, the breakdown voltage of which varies largely with the surface structure. the

US 3,839,612 and US 3,708,638 respectively disclose parallel switching chambers which are connected to each other at least to one potential, for which purpose there are inductive or capacitive sensor taps in order to obtain compensation currents. A series circuit of two vacuum switch chambers is disclosed by US 3813605. the

Contents of the invention

The present invention is therefore based on the object of improving a switchgear of this general type in order to ensure that the degrees of freedom of arc restrike are limited to a good extent and to effectively divide the voltage during the switching process.

In the case of this general type of switchgear, the object stated according to the invention is achieved by the following technical features. the

Switchgear for medium and high voltage ranges, having circuit breakers and/or load interrupters, in which two separate but identical type switches are connected in series in each phase and can be connected in a short The time windows dt are co-controlled relative to each other, and an electrode electrically conductively connected to the two switches and serving as an antenna is arranged between the switching gaps of the two switches, so that the resulting capacitive element is substantially symmetrical. the

The idea now is to sequentially switch the two vacuum chambers on and off at each stage. First, this divides the voltage across multiple switching gaps and exploits the fundamental dependency described above to advantage. Vacuum breakdown, on the other hand, is a very fast process, although in some cases a slightly longer boot time is required. The probability of a breakdown process occurring in the second switching gap at the same time as the first discharge actually occurs is very low. Since only the parasitic capacitance can discharge in the event of a gap partial discharge, there is a high probability that the gap will be re-fortified before complete breakdown occurs. the

The idea of sequentially switching two vacuum chambers is known per se, but is achieved by means of two separate circuit breakers, but of the same type, whose connecting and disconnecting means are coupled electrically and/or mechanically. specific technical characteristics. The special mechanical coupling of the separating rods achieves a synchronization of less than 3ms. This also allows the applied voltage to actually be divided during switch switching. the

An advantageous refinement provides that the switching devices are coupled mechanically. This provides good switching synchronization performance. the

As an alternative thereto, suitable synchronization can also be achieved by electrically coupling the drives of the switching devices. the

In order to also be able to adapt the switching characteristic mechanically and/or electrically to the respective characteristic, the time window dt can be varied by the adjusting device. the

In an advantageous refinement, the optimal time window dt is less than or equal to 3 milliseconds. the

The optimum value occurs at dt = 1 millisecond. the

An advantageous refinement defines that the antennas conductively connected to the two switches are arranged between the switch gaps of the two switches in such a way that the resulting capacitive element is substantially symmetrical. This balancing measure achieves an optimum voltage division between the two switching gaps. This measure is simple but very effective and represents a particularly advantageous preferred development of the switching device according to the invention. the

Another refinement defines that the switches connected in series are physically of the same type. As mentioned above, this is another advantageous measure to effectively balance the voltage division during the switching process. the

It is also advantageous if the two switches are vacuum circuit breakers. the

In a structurally favorable improvement, two switches are arranged on a base plate, and the connections to the busbar and/or cable plugs and/or converters are arranged in a gas-tight enclosure filled with SF ₆ , nitrogen or air as insulating gas. inside the shell. In this way, the switching principle obtained according to the invention can be integrated into conventional switchgear types.

Description of drawings

The present invention will hereinafter be described in more detail and will be illustrated in the accompanying drawings, in which:

Figure 1: Shows a switchgear with only two vacuum circuit breakers per phase. the

Figure 2: shows an equivalent circuit. the

Detailed ways

Two circuit breakers 1 of type VD4X, also used as output or feed panels, are arranged one above the other on a common base plate 2 . The base plate is arranged in a gas-tight manner in front of a pressure-resistant housing. Connections to busbars, cable plugs and converters are arranged in the gas-tight area in a known manner. This document describes an example used in a hermetic ZX1.2 or ZX2 device. the

The input and output coils for the electrical operation of the driver are connected in series or in parallel. Since the timing accuracy of the connections is not particularly critical, the input coils are only electrically coupled. If one of the switches is not connected, a defect message is generated. The switch can then be safely turned off again. the

On the contrary, in order to ensure the partial pressure between the two vacuum chambers, the disconnection operation must be carried out substantially simultaneously. A synchronization of less than 3ms is required due to the slope of the return voltage after the current disappears. In this case, this aspect can be achieved by using the same switch 1 and by a mechanical coupling 2 of the separation lever 3 . The rigid coupling between the two breakaway rods is variable and allows adjustment of the number of breakouts. This achieves a synchronization of less than 3ms, preferably 1ms. the

An electrode 4 can be provided for uniform voltage division between the switching gaps. In the present case, the electrodes increase the coupling between the two vacuum chambers. The position and shape of these electrodes are determined by the position of the switch compartment, especially their capacitance to ground or to a high voltage potential. the

Panels with one capacitor switch can be lined up as required by conventional current output or feed panels by using standard components, especially for the connection of panels to each other, and busbar equipment is preserved. To clearly illustrate circuits that cannot be identified as in Figure 1, Figure 2 shows the equivalent circuit for the entire switching gap, representing all three phases. the

A switch breaker 10 is placed at the output from L1, and ground position 11 constitutes a three-point switch form. the

Two circuit breakers 1 follow in sequence. An electrode 4, which can effectively act as an antenna, is arranged between the respective switching gaps. A capacitive element is formed between said electrode 4 and the respective switching gap of the respective switch 1 . Due to the physical symmetry, which is also evident from Figure 1, they are also symmetric and contribute to the appearance of an intentionally symmetrical distribution of the electrical transition voltage between the two switches during the switching phase. the

Claims (8)

1. Switchgear for medium and high voltage ranges, having circuit breakers and/or load interrupters, in which two separate but identical type switches (1) are connected in series in each phase, and can be controlled cooperatively relative to each other within a short time window dt, and an electrode (4) conductively connected to the two switches and used as an antenna is arranged between the switching gaps of the two switches, so that the resulting capacitive element Symmetrical in nature, the switches (1) connected in series have the same type of construction. 2. Switching device according to claim 1, characterized in that the drive of the switch (1) is mechanically coupled. 3. The switching device as claimed in claim 1, characterized in that the drive of the switch (1) is electrically coupled. 4. The switching device as claimed in claim 2 or 3, characterized in that the time window dt can be changed by means of an adjustment device. 5. Switching device according to claim 2 or 3, characterized in that the time window dt≦3 milliseconds. 6. Switching device according to claim 5, characterized in that the time window dt=1 millisecond. 7. Switchgear according to any one of claims 1 to 3, characterized in that said two switches (1) are vacuum circuit breakers. 8. The switchgear according to any one of claims 1 to 3, characterized in that the two switches (1) are arranged on a common substrate and connected to the busbar and/or cable plug and/or switching The connection of the device is set in an airtight enclosure filled with SF ₆ , N ₂ or air as the insulating gas.

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