CH650619A5 - ARRANGEMENT FOR THE OPERATING VOLTAGE SUPPLY OF A FAULT CURRENT PROTECTION CIRCUIT ARRANGEMENT. - Google Patents

Description

The invention relates to an arrangement according to the preamble of claim 1.

From GB-PS 1 107 879 such an arrangement is already known, in which the neutral conductor and the phase conductor of the feed network and the ground electrode as well as an earth lead of the feed network are always connected via resistors to the relevant connections of the rectification circuit in such a way that they are continuous a current flows from the phase conductor to the earth electrode. Although in certain cases, e.g. 10 to prove a connection between the neutral conductor and the earth electrode, it is recommended that the rectifier circuit is supplied with power via the earth electrode even during normal operation, in other cases the constant presence of a current flowing through the earth electrode is undesirable or even inadmissible. As a result, the possible uses of the known arrangement are limited. Under certain circumstances, the neutral conductor can also have a considerable and even dangerous voltage, the phase and amplitude of which can have a largely arbitrary value. If the voltage and the phase of the neutral conductor approach the voltage of the phase conductor, the fault current protection circuit arrangement can be put out of operation by a strong drop or even disappearance of the supply voltage, which can be very dangerous.

The invention is intended to improve an arrangement of this type in such a way that, while maintaining a continuous excitation of the arrangement for the operating voltage supply, either a current flows through the phase conductor to the earth electrode in the event of a break in the neutral conductor, or an indication is given when a connection between a feed conductor and the earth electrode occurs , which eliminates the disadvantages described above.

This object is achieved according to the invention in an arrangement of the type mentioned at the outset by the characterizing features of claim I.

As a result of this measure, the possible summation of the supply voltages 40 supplied via the various connections of the arrangement for the operating voltage supply takes place under all circumstances on the DC voltage side of the rectification side and not on the AC voltage side.

In the dependent claims, advantageous embodiments of the invention are protected.

Exemplary embodiments of the invention are explained in more detail with the aid of the figures. Show it :

FIG. 1 shows a basic diagram, partly in the form of a block diagram, of the supply from an AC network of a system to which an earth leak detection device with an arrangement according to the invention is assigned,

FIG. 2 shows a diagram similar to that in FIG. 1, in which the system to be fed is assigned an earth leak detection device according to a further embodiment, and

FIGS. 3A, 3B and 3C, schematic diagrams of some embodiments of the arrangement according to the invention that come into consideration for use in the circuits according to FIGS. 1 and 2.

FIG. 1 shows the basic diagram of the supply of an electrical system, shown only in the drawing as load impedance 5, consisting of the phase conductor 1 and the zero conductor 60 of an AC power supply network 3.

In addition to a ground electrode 9, the electrical system 5 is also assigned a residual current protective circuit arrangement, designated as 6, which in the present case consists of a ground leak detection device for controlling a 63 ground leak switch 4, by means of which the system 5 is coupled to the conductors 1 and 2 of the feed network 3 can be interrupted.

Because the operation of the earth leak detection device

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device does not in itself form part of the invention, a schematic indication of the components thereof is sufficient in FIG. 1. These components are formed by an electronic unit 16 fed via the feed conductors 14 and 15 from an arrangement 10 to be described in more detail, which is coupled via a winding W1 to a soft magnetic circuit shown as a toroidal core 17 on which the windings W2 and W3 are also located are arranged. The load system 5 is connected via these last-mentioned windings to the conductors 7 and 8, which, in turn, are coupled to the phase conductor 1 or neutral conductor 2 of the network 3 during normal operation via the earth leakage switch 4, which is then in its closed state. As long as no earth leak of some importance occurs, the winding W1 of the earth leak detection device will not find any asymmetry between the windings W2 and W3 to be considered from primary windings. As soon as earth leakage occurs, asymmetry between the number of ampere-turns of windings W2 and W3 will cause a change in the magnetization state of core 7 such that electronic unit 16 is activated via winding W1 to open-up earth leakage switch 4. The electronic unit 16, and generally the earth leak detection device 6, can be of any suitable type, e.g. as described in Dutch patent application 76.07752. Because the design and mode of operation of components 6 and 16 do not form part of the invention, this brief explanation suffices. In anticipation of the description of the basic scheme according to FIG. 2, it is also noted that the activation of the electronic unit 16 via the winding W1 described above, in addition to a state of asymmetry between the number of ampere windings of the windings W2 and W3, also by introducing a number of fault ampere windings an additional winding W4 can be brought about, as is the case with the basic diagram according to FIG. We will come back to this later.

The locations at which the neutral conductor 2 of the feed network 3 and the earth electrode 9 of the installation 5 are grounded are denoted by 18 and 19 in FIG. 1.

The residual current protective circuit arrangement 6 assigned to the electronic system 5, which in the embodiment described here works as a ground leak detection device, usually requires a low supply capacity and is usually also supplied from the AC network available. In the embodiment described here, this takes place by means of the arrangement 10, in which the first connection 11 and the second connection 12 are connected via the conductors 7 and 8 and the earth leakage switch 4 to the phase conductor 1 and the neutral conductor 2 of the AC network 3, respectively.

If now, e.g. at 20, a break occurs in the neutral conductor 2, not only will the supply of the electrical system 5 via the conductors 7 and 8 be interrupted, but at the same time the supply of the arrangement 10 via the connections 11 and 12, as a result of which the entire earth leak detection device 6 would stop to function, which is perceived as a disadvantage.

The circuit according to FIG. 1 counteracts this disadvantage. In the above-described state that a break occurs at the point 20 in the neutral conductor 2 of the feed network, the conductor 8 becomes one via the electrical system 5, which then no longer carries its normal operating current, and the conductor 7 connected to the phase conductor 1 lead significant voltage that can equal the phase voltage. In addition, as already noted, the electrical system 5 is assigned the ground electrode 9, which can be viewed for practical purposes, at zero potential, i.e. the original potential of the conductor 8.

These phenomena are used in the circuit in that the arrangement 10 is not only equipped with the first and second connections 11 and 12 connected to the conductors 7 and 8, but also with a third connection 13 which is connected to the electrode 9 is such that in the event of a break in the neutral conductor 2, the current supply to the arrangement 10 via the connections 12 and 13, ie via the earth electrode. The details of the arrangement 10 required for this purpose are described in more detail below with reference to FIGS. 3A, 3B and 3C.

The measure described above primarily makes it possible for the earth leak detection device 6 to continue to function even in the event of a break in the neutral conductor of the feed network. The supply, which usually requires a very small capacity, runs through the earth electrode 9 of the electrical system 5.

Secondly, the measure according to the invention creates the possibility of also signaling an increase in voltage on the neutral conductor 2 or of using it to activate the earth leak detection device, even if the voltage on the phase conductor itself has disappeared. For this purpose, reference is made to the basic diagram according to FIG. 2, which corresponds in practically all details (except for the winding W4) to the basic diagram according to FIG. 1, so that the relevant components are also designated with the same reference numbers as in FIG. 1.

As FIG. 2 shows, the third connection 13 of the arrangement 10 is not connected directly to the earth electrode 9, as in FIG. 1, but via the winding W4 of the earth leak detection device 6. The sudden increase in the current through the earth electrode 9 is induced by the winding W4 as interference information in the earth leak detection device 16. The resultant change in the magnetization state of the core 17 has the result that the earth leak detection device controls the earth leak switch 4 so that the entire system is de-energized. The further signaling of this phenomenon will not be discussed further. It should be noted that the use of a winding W4 coupled to the core 7 in the connection between the third connection 13 of the arrangement 10 on the one hand and the earth electrode 9 on the other hand is only an example of the introduction of certain interference information, in this case information about wire breakage, in the earth leak detection device 6, forms. Naturally, other disturbance information can be introduced in a similar or comparable way into a residual current protective circuit arrangement. In the embodiment according to FIGS. 1 and 2, for example, instead of the current increase via the third connection 13 to the earth electrode, the voltage increase between the connections 12 and 13 can be used as the source of interference information. In practice, it will not be difficult for the skilled person to make his choice from the available fault information and the available ways of introducing it into the residual current protective circuit arrangement. It is only important that the residual current protective circuit arrangement 6 continues to function by applying the invention in the event of a break in the neutral of the feed network. Such a residual current protective circuit arrangement can also continue to function in the event of a break in the neutral line, such as signaling, alarming, protecting or in any other desired manner.

3A, 3B and 3C, some embodiments of the arrangement 10 according to the invention are described. The same reference numbers 11-15 as in FIGS. 1 and 2 are always used for the external connections.

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FIG. 3A shows the basic diagram of a rectification circuit working with unilateral rectification, with a series connection of an impedance 21 and a rectifier 22 between the first connection 11 and the positive feed line 14. The series impedance 21 is used to determine the AC voltage present between the conductors 7 and 8 derive the lower AC voltage required to achieve the desired DC output voltage between the feed lines 14 and 15. This can be done in connection with the low current consumption of the residual current protective circuit arrangement 6 by means of the series impedance 21. Any other components, such as a compensation capacitor, have been omitted from the rectification circuit according to FIG. 3A. The second input connection 12 of the arrangement 10 is directly connected to the output feed line 15. If the second connection 12 comes to the potential of the phase conductor 1 as a result of a break in the neutral conductor 2 of the network, as described above, the rectifying effect after the output feed line 14 is effected by a second series circuit consisting of the impedance 23 and the rectifier 24, which is between is arranged directly in FIG. 1 and in FIG. 2 via the winding W4 with the earth electrode 9, the third connection on the one hand and the positive feed line 14 on the other hand. The value of the series impedance, 23 is generally less than or equal to that of the series impedance 21. It will be clear that the series circuit 23, 24 assumes the role of the series circuit 21, 22 in the event of a break in the neutral conductor.

FIG. 3B shows the basic diagram of a rectification circuit working with double-sided rectification. The same essentially consists of the parallel connection of the two series connections of two alternatively effective rectifiers 25 and 26 or 27 and 28. The connection point of the two rectifiers 25 and 26 of the first-mentioned series connection is via a series impedance 21 'to the first connection 11 of the arrangement 10 coupled, while the connection point of the two rectifiers 27 and 28 of the second series connection mentioned is connected directly to the second connection 12 of the arrangement 10. The same can be said about the series impedance 21 'as about the series impedance 21 of the circuit according to FIG. 3A. The two series connections are connected in a conventional manner between the output feed lines 14 and 15. As the invention now proposes, a third series connection of two rectifiers 29 and 30 is also arranged between the lines 14 and 15, the connection point of which is coupled to the third connection 13 of the arrangement 10 via a series impedance 23 '. In the same way as for the rectification circuit according to FIG. 3A, this last-mentioned, third series connection with the rectifiers 29 and 30 becomes effective when the second connection 12 of the arrangement 10 is brought to the potential of the circuit by a break in the neutral conductor 2 (via the electrical system 5) Phase conductor 1 of the network has come. The series impedance 23 ', on the one hand, fulfills the same role as the series impedance 23 in the rectification circuit according to FIG. 3A, but 5, on the other hand, in order to ensure that, when the current flowing through the feed line 15 is operating correctly, a path or a predominant amount of the way through the second connection 12 looking for.

It is noted that although FIGS. 3A and 3B relate to single-phase feed networks, the invention is not limited to them. The phase conductor 1 of the AC network 3 can thus be regarded as one of the phase conductors of a feed network. The arrangement 10 can e.g. be supplied with three first connections 11 15 for supply from a three-phase network, each intended for coupling to one of the phase conductors of the network and connected via an associated series impedance to a bridge circuit for three-phase rectification of the conventional type. Such a rectification circuit is not shown in the drawing, 20 but can also be carried out according to the regulations of the invention. It is only important that in the arrangement according to the invention, in the event of a break in the neutral conductor, the functions of the first connection 11 and the second connection 12 are pushed through after the second connection 12 and the third connection 13, respectively. It is furthermore noted that in FIGS. 3A and 3B arrangements are shown which work without a transformer and essentially consist of rectifiers. However, this should not be viewed as a limitation of the invention. 30 Also with a transformer or with other arrangements that are not shown in the drawing, arrangements can generally be provided in a suitable manner with a third connection for coupling with and possible supply from an earth electrode. The principle diagram according to FIG. 3C only shows a difference with respect to the position of the series impedance 23 'with the diagram according to FIG. 3B. However, this difference is of fundamental importance. As already noted in the discussion of the schematic diagram of FIG. 3B, the presence of the series impedance 23 'means that the current flowing through the feed line 14 has the rectifier 30 (FIG. 3B) or 28 connected to the impedance 23' (FIG. 3C) finds a less good line path to earth than via the other rectifier 28 (FIG. 3B) or 30 (FIG. 3C), so that the current in question will select the latter line path in whole or in large measure, ie in the state according to FIG. 3B via the second connection 12 after the neutral conductor 2 of the feed network 3, but in the state according to FIG. 3C via the third connection 13 after the earth electrode 9. This latter state creates

if an intentionally created earth current is permitted at the point, the possibility of signaling a short between the neutral conductor and earth.

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Claims (6)

650 619 1.Arrange for operating voltage supply of a residual current protective circuit arrangement for an electrical system to be fed from a phase conductor and the neutral conductor of an AC network, to which an earth electrode is assigned, the arrangement having a first rectification circuit and one for connection to the phase conductor and the neutral conductor of the AC network or the first, second or third connection serving the earth electrode is provided such that in the event of a break in the neutral conductor or in a conductor connecting the same to the first rectification circuit, the voltage supply to the first rectification circuit takes place via the earth electrode, characterized in that the third connection (13 ) is connected to the first rectifier circuit (21, 22; 21 ', 25-28) via a second rectifier circuit (24; 29, 30). 2. Arrangement according to claim 1, wherein the first rectifying circuit acts on one side and contains a rectifying element, one electrode of which is coupled to the first connection for connection to the phase conductor of the network, characterized in that the other electrode of the rectifying element (22) is connected via a Rectifier element (24) of the second rectifier circuit, is coupled to the third connection (13) for connection to the earth electrode (9). 2nd PATENT CLAIMS 3. Arrangement according to claim I or 2, wherein the first rectification circuit acts on both sides and contains a parallel connection of at least two series connections of two alternatively effective rectification elements, the connection point of the elements of the first series connection with the first connection for connection to the phase conductor of the network is coupled and the connection point of the elements of the second series connection is coupled to the second connection for connection to the neutral conductor of the network, characterized in that the second rectification circuit, a third series connection of two rectification elements (29, 30) connected in parallel to the parallel connection (25-28) ) contains, the connection point of which is coupled to the third connection (13) for connection to the earth electrode (9). 4. Arrangement according to claim 3, characterized in that either between the third connection (13) and the second rectification circuit (24; 29, 30) or between the second connection (12) and the first rectification circuit (27, 28) has a series impedance ( 23; 23 ') is arranged. 5. Arrangement according to claim 4, characterized by a separate fourth and fifth series connection of two rectifying elements connected in parallel with the whole parallel connection (25-30), the connection points of which with a fourth or fifth connection for connection to the other two phase conductors of a three-phase alternating current network are coupled. 6. Feed device consisting of a residual current protection circuit arrangement and an arrangement according to one of claims 1 to 5, wherein the residual current protection circuit arrangement is equipped with a switching and / or signaling mechanism responsive to a voltage change and / or a current change, which is equipped with a magnetic circuit is provided with one or more detector windings designed in this way and through which the normal operating current of a system fed from the AC network flows, in such a way that the mechanism becomes effective when a change in the normal operating current is detected, characterized in that the fault current flows to the magnetic circuit (17) Protective circuit arrangement (6) associated winding (W4) is arranged between the third connection (13) on the one hand and the earth electrode (9) on the other.