GB2276982A

GB2276982A - Multiple line capacitor

Info

Publication number: GB2276982A
Application number: GB9406290A
Authority: GB
Inventors: Peter Aufleger
Original assignee: Siemens Matsushita Components GmbH and Co KG
Current assignee: TDK Electronics AG
Priority date: 1993-04-05
Filing date: 1994-03-30
Publication date: 1994-10-12
Anticipated expiration: 2014-03-30
Also published as: DE4311124A1; GB2276982A8; CH689844A5; GB9406290D0; FR2703820A1; FR2703820B1; GB2276982B

Description

2276982 MULTIPLE LINE CAPACITOR The invention relates to a multiple line

capacitor.

Anti-interference capacitors for symmetrical and asymmetrical interference suppression are, in conventional filters, connected into the circuit with the aid of terminal leads. As a result, the connection points of these capacitors are inductive and this reduces the attenuation effect. The known capacitors are already equipped with the necessary connecting leads to enable them to be connected into circuits.

According to the present invention, there is provided a multiple line capacitor comprising a plurality of individual capacitors, each defining an aperture through which a respective electrical conductor may be passed, such that one electrode of each individual capacitor makes contact with its respective conductor, the other electrode of each capacitor being connected over a large surface area with a common potential.

The invention thus provides a multiple line feedthrough capacitor. The individual capacitors are preferably arranged as a concentric installation. the capacitor according to the invention enables the conductors to be introduced into the capacitors for contact with one electrode of the capacitors after construction of the multiple line capacitor.

Preferably, the individual capacitors comprise symmetrically operating capacitors. The multiple line capacitor may further comprise an asymmetrically operating capacitor, one electrode of which is connected over a large surface area to a housing potential and the other electrode is connected over a large surface area to the common potential.

Preferably, the electrical conductor, when passed through the aperture of the respective individual capacitor, is coaxial with the electrode thereof.

The invention provides a multiple line capacitor wherein the inductance is as low as possible. Also, when the capacitor is to be installed into filter circuits or other devices, in which interference is to be suppressed, the capacitor can be inter-connected with the conductors of the filter or other device to be used without the need for additional terminal leads.

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Fig. 1 illustrates a multiple line capacitor for symmetrical interference suppression of two phase conductors and one neutral-conductor; Fig. 2 illustrates a filter comprising a plurality of electrical conductors and a capacitor according to Fig. 1; illustrates a multiple line capacitor combination; and illustrates a filter comprising a plurality of electrical conductors and capacitors arranged according to Fig. 3.

Fig. 1 illustrates a multiple line capacitor for a three-conductor filter with two phase conductors 1 and one neutral conductor 2.

The multiple line capacitor comprises, in respect of each line, at least one capacitor 3 for symmetrical interference suppression. Each capacitor 3 is constructed as a concentric assembly through which the respective electrical conductor 1 or 2 is fed. Thus, the capacitors 3 comprise feedthrough capacitors. When the electric conductors 1 and 2 have been introduced into the respective capacitors 3, the capacitors 3 extend coaxially around the conductors 2.

Fig. 3 Fig. 4 The individual capacitors 3 may comprise, for example, a wound capacitor constructed from metallized dielectric foils. The metal coatings which form the different electrodes project outwardly from one end of 5 the winding.

One end of the winding of the capacitors 3 is connected over a large surface area to the earth potential by means of housing PE, while the oppositely disposed electrodes in each case individually contact the electrical conductors 1 and 2. A significant advantage is that the electrical conductors 1 and 2 can be fed through the capacitors 3 during the introduction of the capacitor 3 into a circuit.

Fig. 2 is a circuit diagram for a filter utilizing feed-through capacitors according to Fig. 1. The filter is designed for a number, n, of phase conductors Ll... Ln and one neutral conductor N. The feedthrough capacitors are installed so as to be shielded at high frequencies in the chambers A, and not shielded at high frequencies in the chamber B. The capacitors 3 are connected to individual inductances I in the conductor lines.

Fig. 3 illustrates a second embodiment of multiple line capacitor which, in addition to capacitors 3 for symmetrical interference suppression, comprises a capacitor 4 for asymmetrical interference suppression.

The capacitors 3 are applied individually to the phase conductors 1, whereas the capacitor 4 concentrically surrounds all the electrical conductors 1, 2, one of its electrodes being connected over a large surface area to the earth potential, namely housing PE, and the other electrode being connected over a large surface area to the neutral potential.

The electrodes of the capacitors 3 are, in the embodiment shown in Figure 3, connected on the one hand also over a large surface to the neutral potential and on the other hand to the individual phase conductors 1.

In the case of the capacitor illustrated in Fig. 3, the electrical conductors 1, 2 can be installed in the feed-through capacitor after assembly of the 5 capacitor itself.

Fig. 4 illustrates the capacitor shown in Fig. 3 which is installed in a filter comprising a number, n, of electric conductors Ll... In and the neutral conductor N. Similarly to Fig. 2, the capacitors are installed alternately in chambers A shielded at high frequencies and chambers B not shielded at high frequencies.

The capacitor shown in Figures 1 and 2 is not low in leakage current, as the voltage difference across the capacitor corresponds approximately to the level of the phase voltage. In contrast, the capacitor shown in Figs. 3 and 4 is low in leakage current.

As a result of the omission of the inductive supply lines, the two capacitors are also suitable for applications in filters with very high attenuation requirements. As a result of the arrangement of components and subsequent introduction and contact of the electrical conductors, these capacitors can be used in filters comprising a plurality of chambers shielded at high frequencies as multiple line feed-through capacitors. Furthermore, a low leakage current may be obtained as in the embodiments of figures 3 and 4.

Owing to the omission of contact points in the phase and neutral conductors, the d.c. resistance in the filters to be constructed is reduced, whereby the leakage current, which is determined by this resistance and by the voltage difference between the neutral conductor and the earthed housing potential, is reduced, as in the embodiment shown in Figures 3 and 4.

The multiple feed-through capacitors according to the invention can also be used in place of il I- conventionally employed capacitors (encased capacitors or the like) for the suppression of symmetrical and asymmetrical interference, thereby facilitating an extremely compact construction of filter.

The capacitor according to the invention has lower power loss as a result of the low d.c. resistance resulting from the omission of contact points of the current-carrying lines. The capacitor enables subsequent introduction and concentric contacting of the current-carrying conductors, thereby avoiding the need to use inductive terminal leads of the capacitor as is conventional in the prior art.

The capacitor shown in Figures 3 and 4 also has the advantage of lower leakage current owing to the use of a capacitor of small capacitance for asymmetrical interference suppression and owing to the smaller voltage drop of the current-carrying conductors, in particular of the neutral conductor, because of the omission of contact points.

If required, shielding of the installation at high frequencies is possible without high additional high outlay, through the use of a multi-chamber system.

Thus even better interference suppression behaviour in the high frequency range may be obtained.

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Claims

1. A multiple line capacitor comprising a plurality of individual capacitors, each defining an aperture through which a respective electrical conductor may be passed, such that one electrode of each individual capacitor makes contact with its respective conductor, the other electrode of each capacitor being connected over a large surface area with a common potential.

2. A capacitor as claimed in claim 1, in which the individual capacitors comprise symmetrically operating capacitors.

3. A capacitor as claimed in claim 1 or 2, in which the common potential is a housing potential.

4. A capacitor as claimed in claim 1, further comprising an asymmetrically operating capacitor, one electrode of which is connected over a large surface area to a housing potential and the other electrode is connected over a large surface area to the common potential.

5. A capacitor as claimed in claim 4, in which the common potential is a neutral potential.

6. A capacitor as claimed in any preceding claim, in which each electrical conductor, when passed through the aperture of the respective individual capacitor, is coaxial with the electrode thereof.

7. A capacitor substantially as described herein, with reference to and as shown in Figures 1 and 2, or Figures 3 and 4 of the accompanying drawings.

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