HK1024569B - Overvoltage protection circuit - Google Patents

Description

The invention relates to a surge protective circuit comprising a number of connectors to the wires of a voltage supply system, at least one of which is connected to other connectors, preferably each connector to all other connectors, by means of a series circuit consisting of a surge conductor and at least a thermal insulation.

Transient surges, e.g. caused by lightning, have relatively high energies and can cause damage to electrical systems. It is therefore necessary to provide protection measures to divert such surges. For this purpose, voltage-dependent components are suitable, i.e. those that have a large resistance at low voltages, but a small resistance at high voltages, such as varistors, suppressor diodes, spark plugs. These components are simply switched between the two conductors whose voltage is to be monitored.

The conductor acts as an interruption (except for a small leakage) when the normal operating voltage is concerned, but as a short circuit when a surge is occurring, so that the conductor voltage is considerably reduced and the surge energy is mostly passed through the conductor.

If such a discharge has too high discharge energies, i.e. those exceeding the maximum energy-absorbing capacity of the discharge, this leads to damage to the discharge.

To avoid such fault currents, devices are connected in series to the surge conductor to completely and permanently disconnect a faulty and therefore replaceable conductor from the mains. Since the fault currents described are converted into heat energy in the faulty conductor, i.e. they cause the conductor to overheat, these disconnection devices can operate as a thermal switch, i.e. they interrupt the electrical supply to the conductor as soon as it reaches an unacceptably high temperature.

In multi-line voltage systems, such as three-phase systems, there is often a requirement to monitor or limit any voltage exerted by one line on the other lines, which requires each line to be connected to all other lines by means of a surge conductor.

It may also be necessary to monitor for surges only the voltages between the phase conductors and the neutral or protective conductor, and the neutral or protective conductor shall be connected to the phase conductors by means of a surge conductor.

US 5.032.946 is known as a surge protection circuit, which, in a network consisting of phase, neutral and ground conductor, provides that a voltage-dependent resistor is placed between the phase and the neutral and between the phase and the ground conductor, and that a fuse is attached to the two voltage-dependent resistors for thermal monitoring of the two resistors, providing that the fuse together with the voltage-dependent resistors is placed together in a complex of components or in a single compact component, thus providing a fuse to monitor two resistors.

US 4.587.588 also describes a surge protection system in which a conductor is connected to another conductor by means of two voltage-dependent resistors, each with a fuse attached to the two voltage-dependent resistors.

The disadvantage of such solutions is that if both voltage-dependent resistors are defective at the same time, a high current flow will flow through the components, which can no longer be safely separated by the fuse.

The present invention is therefore intended to describe a surge protection circuit of the type described at the outset, in which all surge-lead components are still thermal protected, but this protection is achieved with the least possible number of thermal protections.

The problem is solved by the features of claim 1.

In the case of simultaneous failure of both interconnected surge-lead components, an unacceptably high current flow is generated across the path: second connecting lamp of the first connecting component - first connecting component - first connecting lamp of the first and second connecting components - second connecting component, which cannot be interrupted by the activation of the thermal insulation pre-loaded on the first connecting lamp, so that the connecting components would be thermally insecure in the event of simultaneous failure.

This ensures that each thermal protection unit simultaneously secures two surge conduction components, reducing the number of thermal protection units required and, consequently, the space required for the entire protective circuit.

This reduces the space required for the surge conductor components and saves the need for separate connecting lines between the first connecting beams.

In this context, the characteristics of claim 2 show the advantages of using an existing thermal insulation in the circuit to achieve the additional thermal protection just discussed, so that the additional thermal insulation does not result in an increase in the number of components.

Providing for the features of claim 3 gives the advantage of incorporating a protective conductor into the protective circuit with particularly low component load.

The characteristics of claim 4 give the advantage that such thermal insulation is functionally reliable due to its simple construction and low geometric dimensions.

Furthermore, the characteristics of claim 5 give rise to the advantage of a particularly simple installation of the circuit of the invention in existing voltage supply systems.

The characteristics of claim 5 give the advantage of a particularly easy and fast-manageable circuit replacement in the event of a failure of one or more surge-lead components.

The invention is explained in more detail below by reference to the accompanying drawings, showing: Fig.1 the current layout of a surge protection circuit for a three-phase DC system with neutral conductor, constructed in accordance with the state of the art;Fig.2 the current layout according to the invention, modified in accordance with Fig.1;Fig.3 the current layout according to Fig.2 in simpler form;Fig.4 the current layout according to Fig.3 with a modification further developing the invention;Fig.5 the current layout of a three-pole version of the protection circuit according to the invention;Fig.6a,b the current layout of five-pole versions of the protection circuit according to the invention;Fig.7 the current layout according to Fig.4 connected with an additional 7' output to protect the single-point connector;Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.Fig.8a.F.Fig.8a.F.8a.F.F.8a.F.F.F.8a.F.F.F.8a.F.F.F.F.8a.F.F.F.F.8a.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F

Figure 1 shows the basic structure and function of a surge protection circuit 10 for a three-phase AC system with neutral N or PEN conductors, respectively.

This protective circuit 1 is intended not only to provide a longitudinal voltage limitation, i.e. to monitor the voltages between the phase conductors LI, L2, L3 and the neutral conductor N or PEN conductor, but also to provide a cross-voltage limitation, i.e. to monitor the voltages between the phase conductors LI, L2, L3. If the voltages of the phase conductors L1, L2, L3 in relation to the neutral conductor N or PEN conductor are to be monitored instead of the voltages of the phase conductors LI, L2, L3 in relation to the protective PE, this connection may be made to the protective circuit 10 instead of the neutral conductor N or PEN conductor.

For the purpose of the above-mentioned purpose of providing both a longitudinal and a transverse voltage limitation, it is necessary to connect each of the connecting devices 1,2,3,4 to the other connecting devices via a surge conductor component VI-V6.

In order to permanently disconnect each V1-V6 exhaust from the circuit in case of failure, as explained at the outset, thermal fuses FI-F6 are connected in series to each VI-V6 exhaust in the manner already explained.

One of the most common embodiments of these thermal fuses FI-F6 is shown in Fig. 9 and 10: it has a fixed contact 11 and a movable contact 12 welded together by means of a solder 13 having a defined melting point. the movable contact 12 is pre-tensioned away from this soldering station, which is achieved, for example, by having the movable contact 12 fixed at the first end, free of a correspondingly pre-tensioned and other ends of the leaf spring 14. this leaf spring 14 can be replaced by an elastic conductor such as an electrical wire, metallic wire rope or a bending conductor such as a bending metal plate, the pre-tensioning of the movable contact 12 must then be produced with other leaf springs, for example, in Fig. 15.

As can be seen from Fig. 1, this contact arrangement is connected in series to a conduit to the drainage element V to be protected, whereby one of the contacts 11 or 12 is connected to a connecting flag A of the drainage element V to be protected. The heat generated in the drainage element V is spread over the electrical line between drainage element V and thermal insulation F and thus also reaches the soldering station.

As shown in Fig. 10, the exhaust element V and its thermal insulation F can be installed in a common housing 16 where the fixed contact 11 is often directly connected to one of the connecting rods A of the exhaust element V, thus ensuring a particularly lossless transfer of heat generated in the exhaust element V to the soldering station.

The requirement, as implemented in the surge protection circuit in Fig. 1, that each switch 1,2,3,4 is connected to each other switch 1,2,3,4 via a surge discharge component V, shows that connecting lamps A of several discharge components V are assigned to one and the same switch 1,2,3,4, i.e. to the same switch 1,2,3,4.

It is intended to connect two surge conductor elements V each, the first connections of which are A1 to the same switch 1,2,3,4, i.e. to connect their first connections A1 directly to each other and to connect this connection via a common thermal insulation F to the switch 1,2,3,4 which is assigned to the first connecting flag A1 of the two surge conductor elements V.

This is shown in Fig. 2: summarized here, V1 with V2; V3 with V4 and V5 with V6. Accordingly, the connecting lamps A11 and A12; A13 and A14 and A15 and A16 are connected to each other by the more strongly shown wires. These connecting wires are each connected to the terminals 1, 2 and 3 by means of a thermal insulation F12 or F34 or F56.

The effect of such a combination is to save three thermal insulators, which allows the entire surge protection circuit 10 to be built in a narrower space. Despite this reduction in the number of thermal insulators, however, all the outlet components V are secured just as in the circuit according to Fig. 1, because each outlet component V is still thermally coupled with the thermal insulation in front of it (symbolized by the dashed lines) via the strongly inserted electrical lines.

The connections of the first connecting rods A1 of the summed outlet elements V, illustrated in Fig. 2 and shown with strong lines, can be made by copper conduits, but the outlet elements V are connected together as shown in Fig. 11:

The first two are placed directly next to each other and are connected in this position by a conductor. This connection is preferably made by soldering the two connecting rods A11, A12. However, it could also be envisaged to produce the two leads V I, V 2 together: it would be possible to form the first connecting rods A11, AI2 as single electrodes and to build the two connecting rods V I and V 2 on both sides of this electrode.

The implementation of the surge protection circuit 10 according to Fig.2 by means of directly welded outlet components V can be shown according to Fig. 3. It should be noted here that for the function of the surge protection circuit 10 according to the invention, it is irrelevant which of the power lines L1 , L2, L3, N or PEN is connected to which connection 1,2,3,4: each connection 1,2,3,4 is connected to each other connection 1,2,3,4 via a surge protection component, so that all possible voltages between the power lines are constantly monitored.

The thermal insulation F common to the two connected outlets V can only interrupt the fault currents flowing through one of the first two connecting lights AI. If both connected outlets V are defective at the same time, a further fault current flowing through both outlets V in series, symbolised by the dashed line 6 in Fig. 3, is produced.

In order to separate the discharge components V even in such fault currents, an additional thermal insulation F shall be installed in the path of these fault currents, which means that the second connecting lamp A2 is connected to the associated connector 1,2,3,4 via this additional thermal insulation F to one of the interconnected surge control components V1,V2, V3,V4, V5,V6.

In Fig. 4 a further thermal insulation F7 is shown in serial form to the second connecting lamp A26 with dashed lines. If such additional thermal insulation F7 were also provided for all other groups of exhaust components, a total of one thermal insulation F would be available per exhaust component V, thus losing the already achieved advantage of the lower number of components.

As shown in Fig. 4 with straight lines, the invention provides for this additional thermal insulation F7 to be formed by the combination of thermal insulation F12, F34, F56 of two other surge conductor components V1, V2, V3, V4, V5, V6.

For this purpose, the second connecting lamp A2, which is to be connected to the same connecting port 1,2,3,4 as the first connecting lamps A1 of another adjacent group of two separate supply components, is connected to these first connecting lamps AI and is thus connected to the corresponding connecting port 1,2,3,4 by means of their common thermal insulation F.

In particular, in Fig. 4, the A22 connector is to be connected to the second hand, as are the first A13, AI4 connectors of the V3, V4 drainage elements. By connecting the A22 connector to the first A13, AI4 connectors, the F34 thermal insulation is now also in series with the V1, V2 drainage elements and can interrupt the current flow indicated in Fig. 3.

In order to trigger this thermal insulation F34, the V1,V2 outlet components must be thermal coupled to it, as shown in the drawing by the dashed lines and in practice by the thermal conductivity of the electrical line between the V1,V2 outlet components and the F34 thermal insulation.

The same interpretations shall apply to the second connecting lamp A24 connected to grip 3 by means of the thermal protection F56 and to the second connecting lamp A26 connected to grip 1 by means of the thermal protection F12.

As can be seen from Fig. 4, the line between A26 and the first connecting elements A11, A12 is relatively long. If, even in the practical implementation of this embodiment of the invention, a long line results, and thus possibly the heat generated by the V5,V6 drainage elements is not transmitted sufficiently to the thermal insulation F 12, the additional thermal insulation F7 can be built in this line in close proximity to the V5,V6 drainage elements and thus thermally well coupled to them. This thermal insulation F7 can then be directly disconnected and, in the event of connection to the first connecting elements A11,A12 at the I drainage, as indicated by a dash.

The surge protection circuit 10 of the invention is not limited to the four-pole design discussed above; as shown in Fig. 5, a three-pole circuit in which each port 1,2,3 is connected to each other port 1,2,3 by a series circuit of a surge conductor component V and at least a thermal insulation F can also be constructed in the manner of the invention.

Such a protective circuit would require only three of the VI,V2,V3 exhaust components, so that only one of the VI,V2 exhaust component couplers of the invention could be formed.

As shown by the dashed line, the second output component V 4 can also be integrated into the circuit, but this is then parallel to the output component V I of the first binary group VI,V2 and thus does not cause any change in the circuit functions.

Such a three-pole protective circuit may be used, for example, to connect the three phase conductors LI,L2,L3 of a rotary current system or the L,N and PE conductors of a single-phase system.

If, in a DC system with neutral conductors, the voltages of the lines LI,L2,L3,N in relation to the PE protective conductor are also to be monitored, a five-pole version of the protective circuit 10 of the invention shall be chosen.

As shown in Fig.6a, a four-pole circuit described so far needs only to be supplemented by a further handle 7, which is also connected to all other handles 1,2,3,4 by a series circuit of a surge-lead component V and a thermal insulation F, each (the series circuits of a surge-lead component V and a thermal insulation F are better represented by straight lines in Fig.6a). The circuit part designated by X in Fig.6a,b is shown as in Fig.3 or 4; two leads, each connected to its first connector A1 at the further handle 7, are connected to the protective connector PEPE, which is connected to the surge-lead component V9 and to the thermal insulation VIO, respectively, in a way which is not common to any other thread, as shown in Fig. 10, F2, F3, F3, F3, F3, F3, F7, F3, F3, F3, F3, F3, F3, F3, F3, F7, F3, F3, F3, F3, F4, and F4, which is connected to the other two leads, respectively, without any further connection to the thermal insulation of each of these handles.

Often the voltages of all the lines of a supply system in relation to the protective conductor PE are not to be monitored for overvoltages, but only the voltage between the neutral conductor N and the protective conductor PE.

To meet this requirement, an additional 7' connector may be provided, as shown in Fig. 7, connected to only one of the other 4 connectors by means of a V12 surge conductor, preferably with a F 13 thermal insulation in series.

In addition to the voltage between neutral conductor N and the protective conductor PE, the voltages of the phase conductors LIL2,L3 in relation to the neutral conductor N must be monitored, as shown in Fig. 7 - the neutral conductor N must be connected to the 4th and the protective conductor PE to the additional 7' connector.

The first connecting the first two connecting points A1 of two surge conductor elements V to the same connecting point 1,2,3,4 and connecting them to the common connecting point 1,2,3,4 by means of a common thermal insulation F, can also be achieved in surge protective circuits 10 where each of the connecting points 1,2,3,4 is only secured against one other connecting point 8.

As shown in Fig.8a, the voltages between the phase conductors LI,L2,L3 or neutral conductor N and the protective conductor PE are monitored; the first connections AI of two surge breakdowns VI,V2 or V3,V4 to be connected to the protective conductor PE are connected to each other and to the protective conductor PE by common thermal insulators F12 and F34 respectively.

Fig.8b also shows a protection circuit 10 for a three-phase network, but here only the voltages between the phase conductors LI,L2,L3 and the neutral conductor N are to be monitored.

As can be seen from these figures, two (Fig. 8a) and one F (Fig. 8b, c) thermal insulation are also saved.

It is also possible to provide for additional F7 thermal fuses connected in series to one of the second A2 connecting lamps.

As regards the design of one of the surge protective circuits 10 according to the present invention, it is intended to arrange all the circuit components in a common housing, which may be designed in a similar way to the housing of an FI or line protective switch, i.e. it may be installed in a distribution box.

In addition, the protective circuit housing can be designed as a plug-in module and a socket can be fitted in a distribution box into which the plug-in module can be connected.

Claims (6)

1. An overvoltage protection circuit (10), comprising taps (1, 2, 3, 4, 7) which can be connected to the conductors (L1, L2, L3, N, PE) of a voltage supply system, with each tap (1, 2, 3, 4, 7) being connected with all other taps (1, 2, 3, 4, 7) via a series connection consisting of an overvoltage arrester component (V) and at least one thermal release (F), with the first terminal lugs (A1) to be connected to the same tap (1, 2, 3, 4, 7) of two overvoltage arrester components (V1, V2; V3, V4; V5, V6) each being joined with each other and are guided via a common thermal release (F) to the associated common tap (1, 2, 3, 4, 7), with the first terminal lugs (A1) to be connected to the same taps (1, 2, 3, 4, 7) of the two overvoltage arrester components (V1, V2; V3, V4; V5, V6) each being joined with each other by sitting directly close to each other, preferably by being soldered, with the second terminal lug (A2) of one of the two overvoltage arrester components (V1, V2; V3, V4; V5, V6) being connected via a further thermal release (F7) to the tap (1, 2, 3, 4, 7) associated with the same.
2. An overvoltage protection circuit according to claim 1, wherein the further thermal release (F7) is formed by the common thermal release (F12, F34, F56) of two other overvoltage arrester components (V1, V2; V3, V4; V5, V6).
3. An overvoltage protection circuit according to claim 1 or 2, wherein an additional tap (7') is present which is connected merely with one of the other taps (4) via an overvoltage arrester component (V12), with which preferably a thermal release (V13) is connected in series.
4. An overvoltage protection circuit according to one of the claims 1 to 3, wherein the thermal releases (F) each comprise a movable contact (12) which is soldered by means of a solder (13) having a defined melting point to a fixed contact (11) and is pretensioned in a direction away from said soldered connection.
5. An overvoltage protection circuit according to one of the claims 1 to 4, wherein all circuit components are arranged in a common housing.
6. An overvoltage protection circuit according to claim 5, wherein the common housing is arranged as a plug-in module which can be inserted into socket which can be mounted in a distributor box.