EP1098332A2 - Rapid current-limiting switch - Google Patents

Abstract

The current limiting switch has an arc-resistant contact arrangement (K1) in a rated current switch (S1), and two commutation paths (P1,P2) connected in parallel to the rated current switch. A first path (P1) includes a contact arrangement (KT) for an isolating switch and a power-electronic switching device (T) connected in series, and the second path includes a switch-off switch (SA) and a current limiting element (RB) connected in series. The contact arrangement (K1) of the rated current switch and the contact arrangement (KT) of the isolating switch are arranged symmetrically about a common axis (A).

Description

TECHNICAL AREA

The invention is based on a current-limiting switch the preamble of claim 1.

Such current-limiting switches can be in the high or medium voltage range as a generator switch, as a tie switch between busbar sections in Switchgear, as a DC switch or in meshed networks for reduction of operating losses are used.

STATE OF THE ART

The invention takes on a prior art of current limiting switches reference, as in the as yet unpublished European application EP Registration no. 98811251.2. This switch has a quick mechanical switching point with galvanic contacts and two in parallel switched commutation paths. The first commutation path are in series a first switching device and an isolating switching point arranged in the second Commutation path are a current limiter and a second switching device in Series switched. The current limiter is designed such that it is guided Current, which when opening the first switching device from the first to the second Commutation path is commutated, is limited with a time delay. During this There can be no time delay over the two commutation paths Build up overvoltage and can also be in the first commutation path overvoltage-proof isolating path are formed.

SUMMARY OF THE INVENTION

The object of the invention is as set out in the claims based on a current-limiting switch of the type mentioned create, which thanks to its special, space-saving structure and the small moving mass because of a quick switching on and off in the up and Medium voltage range enabled.

The current-limiting switch according to the invention has three in parallel to each other arranged paths, two of which contain a mechanical switching point. One of these mechanical switching points is for guiding and switching Rated current, while the other is only briefly and when switching through which a commutated current flows. The Contact arrangements of the mechanical switching points are axially symmetrical trained and arranged coaxially. Thanks to short, coaxial copper connections there are very small leakage inductances, which results in a very fast Commutation of the currents is made possible.

The third path of the switch according to the invention also contains a mechanical one Switching point with a coaxially arranged contact arrangement, is unnecessary conventional current-limiting switches in series-connected series isolators.

If the contact arrangements have different diameters and they are arranged one inside the other, the expansion of the switch in decreases axial direction. This can reduce the dimensions of a housing, in which the contact arrangements are arranged, for example against dust or to be protected from other disruptive influences. The is particularly advantageous Arrangement of the contact arrangements in a pressure-resistant housing, which for example with an insulating gas under atmospheric or higher pressure is filled, which is beneficial to the dielectric property of the contact arrangement affects. If the housing contains two electrically conductive, isolated parts, the nominal current can be connected directly to the connections of the Lead nominal current switching point. Elaborate nominal current feedthroughs through the Housing is thus eliminated.

Do the switching points contain a fast drive for opening and closing the Contact arrangement, can result in different operational requirements corresponding algorithms for opening and / or closing the switch be implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine einphasige Grundschaltung einer ein Mittelspannungsnetz nachbildenden Prüfvorrichtung mit einer ersten Ausführungsform eines strombegrenzenden Schalters nach der Erfindung,

Fig. 2

eine Aufsicht auf einen längs einer Achse geführten Schnitt durch ein Gehäuse mit Schaltstellen des Schalters nach Fig. 1,

Fig. 3

eine einphasige Grundschaltung einer ein Mittelspannungsnetz nachbildenden Prüfvorrichtung mit einer zweiten Ausführungsform eines strombegrenzenden Schalters nach der Erfindung, und

Fig. 4

eine Aufsicht auf einen längs einer Achse geführten Schnitt durch ein Gehäuse mit Schaltstellen des Schalters nach Fig. 3, und

Fig. 5

eine Aufsicht auf einen vergrössert dargestellten Ausschnitt einer Schaltstelle des Schalters nach Fig. 4.

An embodiment of the invention and the further advantages which can be achieved thereby are explained in more detail below with reference to drawings. Here shows:

Fig. 1

a single-phase basic circuit of a test device emulating a medium-voltage network with a first embodiment of a current-limiting switch according to the invention,

Fig. 2

1 shows a plan view of a section taken along an axis through a housing with switching points of the switch according to FIG. 1,

Fig. 3

a single-phase basic circuit of a test device emulating a medium-voltage network with a second embodiment of a current-limiting switch according to the invention, and

Fig. 4

a plan view of a section along an axis through a housing with switching points of the switch of FIG. 3, and

Fig. 5

4 shows a plan view of an enlarged section of a switching point of the switch according to FIG. 4.

WAY OF CARRYING OUT THE INVENTION

In all figures, the same reference numerals refer to parts having the same effect.

The circuit shown in Fig. 1 is a single-phase basic circuit of a test device emulating a medium-voltage network with a first embodiment of a current-limiting switch S according to the invention. The test device contains a generator Q simulating a mains voltage U _N of a few 10 kV, the switch S and a load _L simulated from an ohmic resistor R _L and an inductor L L. A short-circuit current detection unit E is connected between the generator Q and the switch S, which contains a measuring and evaluation part for the very rapid detection of short-circuit currents of up to some 10 kA. The switch S has a nominal current switching point S ₁ located in the current path from the generator Q to the load L. Two commutation paths P ₁ and P _{2 are} connected in parallel with the nominal current switching point S ₁ .

The first commutation path P ₁ contains an isolating switching point S _T and a power electronic switching device T with a diode bridge D ₁ , D ₂ , power semiconductors H that can be switched off, for example GTO, and a surge arrester M. The diode bridge allows switching of alternating currents both with positive and with negative Polarity without power semiconductors connected in anti-parallel.

The second commutation path P ₂ , connected in series, contains a switch-off switching point S _A and a current limiter R _B , which responds to a current with a time delay and is designed, for example, as a PTC resistor. The switch-off switching point can be designed as a semiconductor switch H _A with antiparallel switched, switchable power semiconductors, for example GTOs, or comprise a galvanically isolating mechanical contact arrangement K _A , preferably a vacuum switch.

The switching points S ₁ and S _{T of} the switch according to FIG. 1 each have a contact arrangement K ₁ and K _T that opens very quickly, within a few 100 μs. The contact arrangement K _{1 of} the nominal current switching point S ₁ is arc-proof.

In an advantageous embodiment of the switch according to the invention, the two contact arrangements K ₁ and K _{T of} the switching points S ₁ and S _{T are arranged} in a housing G. On the generator side, the two contact arrangements K ₁ and K _{T of} the switching points S ₁ and S _{T are} connected via a connection 1, a first housing part 10 and primary leads 11 and 12. On the load side, the nominal current switching point S _{1 is} connected to the connection 2 via a secondary feed line 21 and a second housing part 20. The isolating switching point ST of the first commutation path P ₁ is connected to the power electronic switching device T via a secondary feed line 31 which is guided through the housing G with a bushing 5 and via a connection 3.

During operation, the contact arrangements K ₁ and K _{T of} the two switching points S ₁ and S _T and the switch-off switching point S _{A are} closed or conductive. If a short-circuit current occurs, the detection unit E triggers a switch-off process at the current-limiting switch S within approximately 100 μs. The semiconductor elements H lying in the first commutation path P ₁ are immediately made conductive. At the same time, the contact arrangement K _{1 of} the nominal current switching point S _{1 is} opened. Due to two arcs formed in series, the short-circuit current that is still rising commutates into the first commutation path P ₁ within approximately 150 microseconds. The semiconductor elements H remain conductive until a dielectric strength is achieved via the contact arrangement K _{1 of} the nominal current switching point S ₁ , which is greater than the dielectric strength across the semiconductor elements H. Then the short-circuit current in the first commutation path P ₁ is switched off by the semiconductor elements H and commutates into the second commutation path P ₂ . At the same time, the contact arrangement K _{T of} the isolating switching point S _{T is} opened. The second commutation creates both a transient overvoltage due to leakage inductances and an ohmic voltage drop at the current limiter R _B. The current limiter R _B limits with a delay of a few 100 µs. This time delay is sufficient to end the opening process at the contact arrangement K _{1 of} the nominal current switching point S ₁ and the contact arrangement K _{T of} the isolating switching point S _T. After opening the contact arrangement K _{T of} the isolating switching point S _T , practically all of the voltage present at the switch S drops across the isolating switching point S _T in the first commutation path P1. Since the current limiter R _B responds with a delay, the voltage across the switch S and thus across the nominal current switching point S ₁ and the isolating switching point S _T only begins after the contact arrangement K _{1 of} the nominal current switching point S ₁ and the contact arrangement K _{T of} the isolating switching point S _{T are} open . The limited short-circuit current can be switched off in the following current zero crossing, for example after 5 to 6 ms, by the switch-off switching point S _A with a very low transient recovery voltage.

Fig. 2 shows a possible arrangement of the first embodiment of the switch according to the invention. The two switching points S ₁ and S _T are mostly arranged coaxially symmetrically in a cylindrical housing G. The housing G is composed of two plate-shaped, electrically conductive housing parts 10 and 20, a tubular, electrically insulating housing part 7 and two electrically insulating, gas-tight bushings 5 and 6. The housing G is designed to be pressure-resistant and filled with a gaseous medium, for example air or SF ₆ under atmospheric or higher pressure.

The two switching points S ₁ and S _T each consist of a contact arrangement K ₁ and K _T , each with two fixed contact pieces and one movable bridge contact piece, and each with an independently triggerable drive for opening and / or closing the contact arrangement.

The two contact arrangements K ₁ and K _T are arranged one inside the other, the contact arrangement K _{1 of} the nominal current switching point S ₁ , since it requires a corresponding cross section for carrying nominal current, has the largest diameter and is arranged on the outside. The contact arrangement K _{T of} the isolating switching point S _T , through which a commutating current flows only briefly and in a pulse-like manner only when switching, has a correspondingly smaller diameter and is arranged coaxially within the contact arrangement K _{1 of} the nominal current switching point S ₁ . 2, the leads to the contact points are as short and axially symmetrical as possible. In the cylindrical housing G, the nominal current connections 1 and 2 are connected to the outer edge of the plate-shaped, electrically conductive housing parts 1 and 2 and can be tubular, for example. The other supply lines to the contact arrangements, as well as any lines for the controls of the switching points, are advantageously led out of the housing through the middle of the plate-shaped housing parts 1 and 2. Additional bushings, in particular high-current and high-voltage bushings for the nominal current, are no longer required thanks to the integration of housing parts 1 and 2 in the nominal current path.

Fig. 3, the circuit shown in Fig. 1, with an advantageous second embodiment of the inventive switch S. Here, the disconnection switching point S _A comprises a likewise very rapidly open mechanical contact arrangement _KA. Together with the two contact arrangements K ₁ and K _{T of} the switching points S ₁ and S _T , the contact arrangement K _{A of} the switch-off switching point S _{A is arranged} in the housing G. On the generator side, the shutdown switching point S _{A is} also connected via the connection 1 and the first housing part 10 and a primary feed line 13. On the load side, the switch-off switching point S _A is connected to the current limiter R _B via a secondary feed line 41, which is guided through the housing G with a bushing 6 and via a connection 4.

The arrangement of the second embodiment of the switch according to the invention shown in FIG. 4 largely corresponds to the arrangement of FIG. 2. In addition to the two switching points S ₁ and S _T , the switch-off switching point S _{A is} arranged coaxially symmetrically in the housing G.

With this embodiment, with galvanic isolation in each of the three parallel ones Current paths, there is no need to use an additional series isolator become.

An advantageous embodiment of the drive of a switching point looks next to one movable bridge contact piece, which is part of the contact arrangement of the switching point is essentially two coils and a power electronic control unit. The contact arrangement and the coils are axially symmetrical and arranged coaxially to each other. The exact structure of the three switching points will with reference to a section of the arrangement shown in FIG. 2 shown in FIG explained. The two coils 81 and 82, which drive one The switching point belongs, on both sides of the associated one, as a contact ring 85 trained bridge contact piece arranged offset in the axial direction. The Contact ring is acted upon by electrodynamic force from the Power electronic control unit fed into the corresponding coil of energy becomes. The contact ring can be in the axial direction between the two coils 81 and 82 are moved back and forth while opening the contact arrangement and again conclude. In the closed state of the contact arrangement, the contact ring 85 fitted between the two fixed switching pieces 84 and closes them short. In the open position of the contact arrangement, the contact ring 85 of held a holding part 83.

LIST OF DESIGNATIONS

1, 2

Nominal current connection on the housing

3.4

Secondary connection for isolating switching point, switch-off switching point

5, 6

Implementation of the secondary connections

7

Electrically insulating housing part

10, 20

Electrically conductive housing part

11, 12, 13

Primary supply line to the switching point

21,31,41

Secondary supply line to the switching point

81.82

Drive coils

83

Holding part

84

Fixed contact pieces

85

Contact ring

A

Axis of symmetry

D ₁ , D ₂

Diode bridge

E

Short circuit detection unit

G

casing

H

semiconductor

H _A

Semiconductor switch

I _N

Rated current

K ₁ , K _T , K _A

Contact arrangements

L

load

L _L

Load inductance

M

Surge arresters

Q

Power source, generator

R _B

Current limiter

R _L

Ohmic load resistance

s

Current limiting switch

S ₁ , S _T , S _A

Rated current, isolating, switch-off switching point

T

Power electronic switching device

U _N

Mains voltage

Claims (12)

Current-limiting switch (S) with an arc-resistant contact arrangement (K ₁₎ rated-current switching containing (S ₁₎ and with two connected in parallel with the rated-current switching point (S ₁₎ Kommutierungspfaden (P _1, P _2), of which a first (P ₁₎ in series switched a contact arrangement (K _T ) of an isolating switching point (S _T ) and a power electronic switching device (T) and a second connected in series contains a shutdown switching point (S _A ) and a current-limiting element (R _B ), characterized in that the contact arrangement ( K ₁ ) of the nominal current switching point (S ₁ ) and the contact arrangement (K _T ) of the isolating switching point (S _T ) are formed and arranged symmetrically with respect to a common axis (A). Switch according to Claim 1, characterized in that the switch-off switching point (S _A ) has a galvanically isolating contact arrangement (K _A ) and that this contact arrangement (K _A ) is designed and arranged symmetrically with respect to the common axis (A). Switch according to one of claims 1 or 2, characterized in that the contact arrangements (K ₁ , K _T , K _A ) of the switching points (S ₁ , S _T , S _A ) have different diameters and are arranged one inside the other. Switch according to one of claims 1 to 3, characterized in that the contact arrangements (K ₁ , K _T , K _A ) of the switching points (S ₁ , S _T , S _A ) are arranged in a housing (G). Switch according to claim 4, characterized in that the housing is cylindrical and that the contact arrangements (K ₁ , K _T , K _A ) of the switching points (S ₁ , S _T , S _A ) and the housing (G) with respect to a common axis (A) are arranged coaxially. Switch according to one of claims 4 or 5, characterized in that the Housing (G) is designed to be pressure-resistant. Switch according to one of claims 4 to 6, characterized in that the Housing has at least two electrically conductive housing parts (10, 20), the with each other via at least a third, electrically insulating housing part (7) are connected. Switch according to claim 7, characterized in that the two are electrical conductive housing parts (10, 20) are plate-shaped, and that electrically insulating housing part (7) tubular and between the plate-shaped housing parts (10, 20) that the two plate-shaped housing parts (10, 20), the tubular housing part (7) on the end face limit. Switch according to one of claims 7 or 8, characterized in that a common primary feed line (1, 11, 12, 13) to the contact arrangements (K ₁ , K _T , K _A ) of the switching points (S ₁ , S _T , S _A ) over a first of the two electrically conductive housing parts (10) that a secondary supply line (2, 21) to the contact arrangement (K ₁ ) of the nominal current switching point (S ₁ ) is guided over the second of the two electrically conductive housing parts (20) , and that the secondary leads (3, 31, 4, 41) to the contact arrangements (K _T , K _A ) of the other switching points (S _T , S _A ) are guided through the housing. Switch according to one of claims 1 to 9, characterized in that each of the switching points (S ₁ , S _T and S _A ) for opening and / or closing the contact arrangements (K ₁ , K _T , K _A ) contains a drive. Switch according to claim 10, characterized in that the drive generated electrodynamic force. Switch according to claim 11, characterized in that the drive two Coaxially offset coils (81, 82), one coaxially between the coils arranged, axially movable contact ring (85) and a Power electronic control unit, wherein the contact ring (85) in closed state of the switching point two coaxially arranged, fixed Short-circuits contact pieces (84).

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