WO2004021567A1

WO2004021567A1 - Feedthrough component, filter circuit provided with the feedthrough component, and shielding wall for shielded spaces

Info

Publication number: WO2004021567A1
Application number: PCT/DE2003/002893
Authority: WO
Inventors: Wilhelm Grimm; Peter Schweiberger; Gerhard Stelzl
Original assignee: Epcos Ag
Priority date: 2002-08-30
Filing date: 2003-09-01
Publication date: 2004-03-11
Also published as: DE10240084A1

Abstract

The invention relates to a feedthrough component provided with a housing (1), with a feedthrough (2) led through the housing (1), with a series connection (3), which consists of two capacitors (C1, C2) and which is connected between the feedthrough (2) and the housing (1), and with a conductor (4) that is led from the center tap (51) of the series connection (3) out of the housing (1). The frequency diplexer can prevent considerable reactive currents from loading the ground. The invention also relates to a filter circuit provided with said feedthrough component and to a shielding wall for shielded spaces.

Description

description

Feedthrough component, filter circuit with the feedthrough component and screen wall for shielded rooms

The invention relates to an electrical feedthrough component that contains a capacitor. The invention further relates to a filter circuit with the bushing component. The invention further relates to a screen wall for screened rooms.

Multi-phase power lines generally have multiple phase lines and a zero line. To suppress the phase lines, an interference filter in the form of a bushing component is used for each line.

Feedthrough components are known from the publication DE 198 35 843 C2, in which a feedthrough is provided in an HF-tight housing and in which a capacitor is connected directly to the feedthrough and to the housing in order to counteract high-frequency disturbances caused by the feedthrough derive the earth connected to the housing. Such feedthrough capacitors for interference suppression of power lines have the disadvantage that, due to the capacitance of the capacitor, a reactive current is also generated, which must then be derived via the grounding of the housing.

The reactive current is generated by the useful frequency which is continuously or quasi-permanently present on the bushing and which corresponds, for example, to the network frequency in the range of 50 Hz.

As a result, such a component can only be used to a limited extent, since, for example, the operation of residual current circuit breakers in front of such feedthrough capacitors is not possible or relevant safety standards prohibit their use. From the publication DE 2456088 A a bushing component is known which has a bushing for one phase and a further bushing for a center conductor. This component is designed for a power supply with only one phase and a neutral conductor and is not suitable for use in multi-phase power supply systems for reasons of cost.

It is an object of the present invention to provide an inexpensive bushing component in which the occurrence of reactive currents in the area of the housing is reduced and which can be used in power supply systems with any number of phases.

This object is achieved by a bushing component according to claim 1. Advantageous embodiments of the bushing component, a filter circuit with the bushing component and a screen wall for shielded rooms can be found in the further claims.

A feed-through component is provided which is provided with a housing. Furthermore, the component is provided with a bushing which is guided through the housing. The bushing is electrically conductive and preferably enters the housing at one point in the housing and exits the housing at the point on the housing opposite the entry point. Advantageously, the bushing runs straight through the housing.

A series connection of two capacitors is also provided. The series connection is connected between the bushing and the housing of the component. A conductor, which is led out of the housing, is contacted at the center tap of the series connection.

The conductor that is preferably to be connected to the zero line of the corresponding power supply system is, in contrast, set to a z. B. from the publication DE '2456088 A, designed as a feeder center conductor - formed as a stub that emerges from the housing at only one point of the housing.

The feedthrough component has the advantage that a crossover can be realized by the described construction of the series connection of two capacitors and the center tap. Through a suitable choice of the capacitances of the two capacitors, frequencies in the range of

Usable frequency are to be derived via the center tap of the series circuit, while frequencies which are in the range of the interference frequencies can be derived to the housing via both capacitors. The occurrence of high reactive currents in the housing, which are generally generated by the useful frequency, which is, for example, in the range of 50 Hz, can be reduced by deriving these frequencies through the conductor.

The configuration of the conductor in the form of a stub according to the invention has the advantage over a trained as center conductor carrying the advantage that it can be manufactured at low cost and universally sen ^'in single-phase and multi-phase power lines with any number of phases can be used.

In a multi-phase system, z. B. an interference filter according to the invention (feed-through component) is used, the stub lines of the interference filters being electrically connected to one another and preferably also to a zero line.

Due to the special design, the feedthrough filter according to the invention has attenuation values up to the GHz range. This makes it stand out from the usual EMC circuits. A filter circuit is also specified with a component of the type just described, the feedthrough being connected to a phase, the conductor to a neutral conductor and the housing to an earth. The bushing is thus connected to the phase, while the conductor, which is intended to derive the signals lying above the first capacitor, is at the potential of the neutral conductor of the circuit. The reactive current, which is mainly caused by the useful frequencies, can therefore be derived via the neutral conductor, which reduces the load on the earthing.

Since the voltage between the neutral conductor and the earthing is again very low (ideally 0 V), very low leakage currents arise, which can even extend to the absence of leakage current.

The component described can be used very universally, both in single-phase and - then in a corresponding number - multi-phase filters. This reduces the

Variety of parts in the manufacture of EMC filters.

It is advantageous if the capacitance of the capacitor, which is directly connected to the housing, is smaller than the capacitance of the capacitor, which is directly connected to the bushing. This enables the low-frequency useful currents to be derived via the center tap, while high-frequency interference can be derived via the housing of the bushing component.

Furthermore, in order to implement a symmetrical construction which is simple to manufacture and which is also compact, it can be provided that the capacitors are wound capacitors, the windings of which are arranged around the bushing. In addition, two winding capacitors can be arranged concentrically to one another. Alternatively, two winding capacitors can also be arranged next to one another on the bushing.

It is also advantageous if the component contains one or more inductors which are connected to the capacitors in the component.

For example, an inductor can be connected in series for implementation. In addition, it is also possible to connect an inductor in series with the conductor.

^• In addition, a component is advantageous which comprises a further series connection of two capacitors, which is connected between the bushing and the housing, and in which an inductance is connected between the connection points of the series circuits with the bushing, and in which between the Another inductance is connected to the taps of the series connections. This enables the implementation of a τr filter, which has the advantage of even better filter properties.

An inductance can advantageously be formed by an annular core arranged around the bushing and possibly around the conductor. Such a construction has the advantage that little space is required for the inductance.

A screen wall for a screened volume is also specified, to which a component of the type described above is fastened by screwing the housing to the wall on the screened side of the wall. In this context, for example, an application in magneto-resonance rooms (magnetic resonance tomography) is possible, in which current for the lighting and for sockets must be led through the screen wall. Any phase can are protected against high-frequency interference by a described lead-through component.

When used in filter circuits or devices, the bushing component can also be operated in parallel to increase the current carrying capacity.

When used in filter circuits or devices with multi-phase power supply, one or more bushing components can be used for each phase connection. This creates a modular structure that reduces the number of parts and increases flexibility when using the components.

Furthermore, the mechanical design of the bushing component can be designed so that it is compatible with known bushing components according to the prior art described above. This makes it possible to retrofit devices to the bushing component described here without any additional effort.

The invention is explained in more detail below with reference to exemplary embodiments and the associated figures.

Figure 1 shows a bushing component partly in a longitudinal section, partly in a plan view.

FIG. 2 shows an equivalent circuit diagram for a component according to

Figure 1.

Figure 3 shows a bushing component, partly in one

Longitudinal section, partly in a top view.

FIG. 4 shows an equivalent circuit diagram for a component according to FIG. 3. FIG. 5 shows an equivalent circuit diagram for a bushing component which is designed as a ττ filter.

FIG. 6 shows a filter circuit with two lead-through components.

Figure 7 shows an arrangement of bushing components for use in shielded rooms.

FIG. 8 shows an equivalent circuit diagram for the arrangement of bushing components according to FIG. 7.

FIG. 1 shows a bushing component in which a housing 1 is arranged rotationally symmetrically around a bushing 2. The bushing 2 has the form of a solid metallic bolt, which is provided with a thread in places. Threaded sections of the bolt 2 are provided with nuts 16. With the help of these nuts 16, the component can be connected in a filter assembly.

The housing 1 consists of metal, for example brass, copper or steel, preferably aluminum, and is used for high-frequency shielding of the component from the outside. Furthermore, the housing 1 is sealed inwardly at a narrow point of the housing 1 with a seal 15a against moisture, which can be, for example, a casting compound or a PU adhesive.

The housing 1 has the shape of a pot which is open towards the left side, the left open side being sealed from moisture by a casting compound 15.

The housing 1 is provided in a tapered section with a thread onto which a nut 17 is screwed. The bushing component can be mounted in a filter assembly by means of the nut 17. In addition, the housing 1 is sealed against moisture and other climatic influences.

Two capacitors C1 and C2 are arranged inside the housing 1. These are wound capacitors which are arranged concentrically with one another and for the passage 2. The capacitors C1, C2 are connected to one another in an electrically conductive manner via a connecting element 18, which can be a metal sheet, for example. The capacitor C1 is also connected to the bushing 2 in an electrically conductive manner. The capacitor C2 is electrically conductively connected to the housing 1 on the opposite side. A conductor 4 is connected to the center tap 51 between the two capacitors C1, C2, which is electrically conductive and which is led out of the housing 1 to the outside. The external circuitry of the bushing component is given by the left end of the bushing, connection AI and the right end of the bushing, connection A2. In addition, there is also the connection B, which is formed by the conductor 4 led out of the housing 1. Another connection E is formed by the housing 1.

The connection B or the conductor 4 is designed in the form of a stub line, the conductor 4 not being a lead-through line.

With reference to the connections AI, A2, B, E in FIG. 1 and to the capacitors C1, C2 in FIG. 1, the equivalent circuit diagram for the component shown in FIG. 1 is shown in FIG. The electrically conductive connection is shown, which is formed by the bushing 2 and which connects the connections AI, A2 to one another. A first series circuit 3 of capacitors C1, C2 is also shown. The series circuit 3 is connected to the bushing 2 in an electrically conductive manner at the connection point P1. The series circuit 3 is connected to the terminal E on the side opposite P1. The center tap 51 between the two Capacitors C1, C2 are connected to the conductor 4, which forms the connection B outside the housing. By means of the connecting element 18, the two capacitors C1, C2 are connected to one another in an electrically conductive manner to form a series connection. Suitable capacitors for the capacitors C1, C2 are, for example: Cl = 4 μF; C2 = 0.5 μF.

With its capacitance of 4 μF, the capacitor C1 is suitable for forming a low impedance for the useful frequencies, which are, for example, 50 Hz. With its capacitance of 0.5 μF, the capacitor C2 is suitable for forming a high impedance for the useful frequency. At the same time, the capacitor C2 is kept at a low voltage potential by the terminal B, which is why the useful frequency is not derived to the terminal E but preferably to the terminal B. It can thereby be achieved that the connection E is loaded only to a very small extent with reactive currents which originate from the useful frequency.

In addition, the capacitor Cl or

Series connection of the capacitors Cl and C2 is suitable for • forming a very low impedance for an EMC (electromagnetic compatibility) interference signal in a frequency range between 1 MHz and 40 GHz, since in the series connection of the capacitances the total capacitance from the very small capacitance C2 is dominated. As a result, the interference signal can be derived very easily against connection E, and connection B receives only a very small proportion of the interference signal.

FIG. 3 shows a bushing component in a manner analogous to that of FIG. 1, with the difference that a toroidal core 7 is arranged inside the housing 1 to form two inductors. The toroidal core 7 is fixed by means of potting compound and sealed to the outside. The toroidal core 4 is preferably made of carbonyl iron and is preferably soft magnetic. The toroidal core 7 induces inductances for all electrical conductors running inside the toroidal core 7. forms. Thus, it is an inductor formed by the bushing 2 in connection with the Ringk ^'s 7. It is further an inductor formed by the conductor 4 in connection with the ring core. 7

In a manner analogous to FIG. 2, a series circuit diagram for the component shown in FIG. 3 is also shown in FIG. The connections AI, A2 are connected to one another by bushing 2. A first inductor L1 is connected in series to bushing 2. This inductance L1 is formed by the bushing 2 together with the toroidal core 7 from FIG. 3.

In addition, a circuit of capacitors C1, C2 is shown, which is connected in an analogous manner to that shown in FIG. 2 with the connections AI, A2, B and "E. In addition to the circuit shown in FIG. 2, there are also an inductor L2, which is formed in series with the conductor 4. The inductor L2 is connected between the center tap 51 between the capacitors C1, C2 and the terminal B. The circuit shown in FIG. which has better damping than a circuit according to FIG. 2.

Another embodiment of the feedthrough filter, this time only with regard to the circuit diagram, is shown in FIG. Analogously to FIG. 2 and FIG. 4, a connection of the connections AI, -A2 is implemented by a bushing 2. There is also a first series circuit 3 of capacitors C1, C2 and a second series circuit 6 of

Capacitors C3, C4. Each of the series circuits 3, 6 is electrically conductively connected to the bushing 2 at a connection point P1 or P2. The connection points P1, P2 have an inductance L1 connected in series to the feedthrough 2. The inductance L1 can be designed, for example, as in the manner described in FIG. 3. In addition, a further inductor L2 is provided, which is connected in series for the connection between the center taps 51, 52 of the series circuits 3, 6. The inductance L2 can be designed in accordance with the manner shown in FIG. 3 by passing the conductor 4 through an annular core 7. Connections of the series circuits 3, 6 located on the opposite sides of the connection points P1, P2 are each connected to connection E. The center taps 51, 52 are connected to one another by means of the inductance L2, the center tap 51 being connected to the external connection B via the conductor 4.

The illustrated in Figure 5, a circuit ττ filter is realized that particularly good filter characteristics allows for unloading of electromagnetic ^{disturbances'} disturbances in filter circuits.

The useful frequency is in the range of 50 Hz, while the interference frequencies are in the range between 1 MHz and 40 GHz. Suitable values for Cl, C2, C3, C4 and L1 and L2 in order to obtain a suitable crossover or a suitable r-filter according to FIG. 4 or FIG. 5 at the frequencies 50 Hz / 1 MHz are as follows: Cl = C3 = 4 μF; C2 = C4 = 0.5 µF; Ll = L3 = 360 nH.

FIG. 6 shows a mains line filter that can be used to suppress mains lines. The power line filter from FIG. 6 is characterized by high interference suppression. The mains cable filter is provided with a phase PL1, which can be connected to the primary or to the secondary side of the filter. In addition, the filter is provided with a connection for a neutral conductor N. In addition, the filter is provided with a connection for the earth. A feed-through component 8, 9 is connected in series with the phase PL1 on the primary and on the secondary side, as a result of which an effective interference suppression of the PLI can be achieved. The resulting from the bushing components 8, 9 Executed conductor 4 is electrically conductively connected to the neutral conductor N. Furthermore, the housing 1 of the bushing components 8, 9 is connected to a shield of the filter, which in turn is connected to the earth. The exemplary embodiment from FIG. 6 shows the use of the bushing component in a single-phase mains line filter with high blocking attenuation. In the circuit according to FIG. 6, the high-frequency signals (EMC interference) are derived via the two capacitors of the respective bushing components 8, 9 with low inductance to the housing 1 or to earth. In contrast, low-frequency leakage currents are returned via conductor 4 to the electrical system or to the neutral conductor N.

The bushing component according to the invention is particularly suitable for medical technology applications in the 100 MHz range, such as, for. B. suitable for magnetic resonance imaging, since it ensures the good, previously unattainable high-frequency interference suppression of the power supply with a compact structure for detecting the weak RF signals.

FIG. 7 shows the use of lead-through components 11, 12, 13, 14 for the introduction of power supplies in magneto-resonance rooms, as are used for example in magnetic resonance imaging. A screen wall 10 is provided which is electrically conductive and which consists, for example, of aluminum. The screen wall 10 is connected to an earth. Four bushing components 11, 12, 13 and a bushing element 14, which can be constructed according to the example from FIG. 1, are screwed to the screen wall by means of nuts 1711, 1712, 1713, 1714, which correspond to the nut 17 from FIG 10 screwed. On its right side, each bushing component forms a connection for a phase PL1 ', PL2, PL3 or for a neutral conductor N. For this purpose, nuts 1611, 1612, 1613 and -1614 are provided, on which electrical contacts are made to the bushings of the bushing construction - elements can be manufactured. Correspondingly, bushing components 11, 12, 13, 14 are arranged on the side opposite the input side for the production of contacts. The screwing of the bushing components 11, 12, 13, 14 is carried out on the shielded side. Each bushing component 11, 12, 13 is provided with conductors 411, 412, 413, which are combined to form a conductor 400 and which are connected to the bushing component 14 by screwing by means of nuts and are therefore connected to the neutral conductor N. The screen wall for a screened volume can also be used for screened devices. '

FIG. 7 shows the use of the bushing component in a multi-phase power supply system, identical or similar bushing components being able to be used for each phase, as a result of which the number of parts can be reduced.

FIG. 8 shows an electrical circuit diagram which is realized by the structure shown in FIG. 7. Phases PL1, PL2, PL3 are connected to one another by bushings. Furthermore, series connections 311, 312, 313 of capacitors are shown, which on the one hand can discharge high-frequency interference against an earth, and in which the low-frequency spaces can be returned to the neutral conductor N at a center tap. It is also shown that the lowermost bushing component, which corresponds to bushing component 14 in FIG. 7, has only one capacitor 314, which is connected to the bushing and to earth.

The present invention is not limited to filters for EMC interference in the range of 1 GHz, but can be used for all types of interference in which a low-frequency useful frequency and a high-frequency interference frequency or a low-frequency interference frequency and a high-frequency useful frequency to be separated from each other.

Reference character list

1 housing

2 implementation

3, 6 series connection

4 conductors

51, 52 center taps

7 toroid

8, 9 bushing component

10 screen wall

11, 12, 13, 1 bushing component

15a sealing

15 potting compound

16, 17 mother

18 connecting element

1711, 1712, 1713, 1714 mother

1611, 1612, 1613, 1614 mother

411, 412, 413, 40C) conductor

PLl, PL2, PL3 phase

311, 312, 313 series connections

314 capacitor

AI, A2 connection

B connection

E connection

N neutral conductor

PL phase

Cl, C2, C3, C4 capacitor

Pl, P2 connection point

Ll, L2 inductance

Claims

claims

1. Feedthrough component

- With a housing (1) - With a bushing (2) guided through the housing (1),

- With a series circuit (3) of two capacitors (Cl, C2), which is connected between the bushing (2) and the housing (1),

- And with a conductor (4), which - from the center tap (51) of the series circuit (3) out of the housing (1), the conductor (4) is not a bushing and is designed as a stub.

2. Component according to claim 1, wherein the capacitance of the capacitor (C2) directly connected to the housing (1) is smaller than the capacitance of the capacitor (Cl) connected to the bushing (2).

3. Component according to one of claims 1 or 2, in which both capacitors (Cl, C2) are wound capacitors, each winding being arranged around the bushing (2).

4. The component according to claim 3, in which two winding capacitors (Cl, C2) are arranged concentrically to one another.

5. The component according to claim 3, in which two winding capacitors (Cl, C2) are arranged side by side on the bushing (2).

6. Component according to one of claims 1 to 5, which contains one or more inductors (L1, L2) which are connected to the capacitors (Cl, C2, C3, C4).

7. The component according to claim 6, in which an inductor (L1) is connected in series to the implementation (2).

8. Component according to one of claims 6 or 7, in which an inductor (L2) is connected in series with the conductor (4).

9. The component according to one of claims 1 to 8,

- With a further series connection (6) of two capacitors (C3, C4), which is connected between the bushing (2) and the housing (1),

- In which an inductance (L1) is connected between the connection points (Pl, P2) of the series connections (3, 6) with the leadthrough (2), - and in which between the center taps (51, 52) of the series connections (3, 6 ) another inductor (L2) is connected.

10. The component according to one of claims 6 to 9, in which an inductor (L1, L2) is formed by a ring core (7) arranged around the bushing (2).

11. Filter circuit with a component (8, 9) according to one of claims 1 to 10, wherein the bushing (2) is conductively connected to a phase (PL), the conductor (4) having a neutral conductor (N) and the housing (1) is conductively connected to an earth.

12. Filter circuit with a component (8, 9) according to one of claims 1 to 10, which comprises several phases, at least one bushing component being provided per phase, the stub lines of the bushing components provided for different phases being conductively connected to one another.

13. Filter circuit according to claim 12, comprising a zero line, in which the stub lines of the feed-through components provided for different phases are conductively connected to the neutral line.

14. Screen wall for a screened volume, to which a bushing component (11, 12, 13) according to one of claims 1 to 10 is attached by screwing the housing (1) to the screen wall (10) on the screened side of the wall (10) is.