EP2127992B1 - Circuit for monitoring the end position switches of a four wire three phase drive for points - Google Patents

Abstract

The circuit (10) has switch point monitors (WUEA, WUER, WUEL) for signaling of a link position and a right position. The switch point monitors generate drive signals and comprises optocouplers polarized against each other and supplied with monitoring voltage with a negative polarity. End position switches (S1.1, S1.2, S2.1, S2.2) reflect the monitoring voltage with a positive polarity between connection points (U, V, W) corresponding to a position of the switches and excitation voltage is fed to the monitors for activation of the monitors and generating the drive signals.

Description

The invention relates to a circuit for monitoring limit switches of a 4-wire three-phase drive of a switch and to generate a message about the current order position of the switch or a Auffahrmeldung.

Such circuits are well known. To monitor the limit switches of a 4-wire three-phase drive of a turnout and to generate a message about the current order situation of the turnout or a Auffahrmeldung circuits are still used without exception, which build on a current-based monitoring due to increased Störspannungsfestigkeit. These circuits are therefore based on an evaluation of different current flows in the circuits to determine from the positions of the limit switches, the regulatory positions "left" or "right" or the position "Aufgefahren" of switches. An approach message is generated by means of an overcurrent message. The overcurrent in a monitoring circuit is generated by a short-circuit via the point monitor in the ascended state of a switch. These circuits are characterized in particular by the ability to set and monitor distances of up to 6.5 km. This results not least from the fact that such monitoring is not potential-controlled and thus relatively robust to interference and external voltages. In practice, such circuits for a decentralized interlocking are relatively disadvantageous. So facilities or components for power monitoring are constructively extremely expensive and thus costly in their production. Furthermore, a classic start-up message results from an occurring, excessive monitoring current (for example, 300 mA instead of 30 mA), which tolerates only a relatively narrow range of values, which starts at approximately 250 mA.

In addition, the describes DE 30 43 661 A1 An institution at an electronic interlocking for food and remote monitoring turnout drives. In this device, a potential-free monitoring voltage is supplied to two connection points of the switch. The device comprises inter alia three monitors, which are each designed as optocouplers. A monitoring current is passed to the first supervisor and the second or, alternatively, to the third supervisor. The activation of the individual monitors is then applied to a control computer, which can determine from this only the current point location according to a logic impressed him. In addition, for example, activation of the first monitor together with the second or third monitor indicates the "left" or "right" position message. Activation of only the first supervisor, ie without activation of the second or third supervisor, signals an upset turnout. Therefore, the position message must be omitted in any case, to mark the switch as "Aufgefahren". Such a circuit is error-prone.

Finally, out of the DE 36 38 681 A1 another device for remote monitoring of three-phase soft-drives with an integrated Polwendeumschalter known. In this device, a supply of a potential-free monitoring voltage is again at two connection points of the switch. Different polarities lead to activation of a first monitor for signaling the left position or a second monitor for reporting the legal status of a switch, the Polwendeschalter this influence deciding. A Auffahrmeldung the switch is in contrast generated by a third monitor when positive potential can form at the third monitor with appropriate contact one of the two limit switches for the left position or one of the two limit switches for the legal situation. It is therefore responsible for the Auffahrmeldung depending on the Polwenders either a limit switch for the left position or a limit switch for the legal situation. By the Polwendeumwandler also designed the monitoring circuit in itself in their construction as relatively expensive. Apart from that, due to the integrated in the monitoring circuit Polwendeumwandlers accurate error assignment and thus recognition of the three-phase soft-start drive can not easily reach.

The invention is therefore an object of the invention to provide a circuit for monitoring limit switches of a 4-wire three-phase drive a switch and to generate a message about the current order of the switch or a Auffahrmeldung available, with which prevent the aforementioned disadvantages which is therefore structurally particularly simple, efficient and at the same time extremely reliable, moreover inexpensive and extremely trouble-free as well as failsafe.

This object is achieved in a surprisingly simple manner by the features of claim 1.

Accordingly, the design of the circuit according to the invention for monitoring limit switches of a 4-wire three-phase drive a switch and to generate a message about the current order position of the switch or Auffahrmeldung, the four limit switches of the switch, of which two a switch blade of the switch for Linksichen and two of the legal situation are assigned, and includes a Weichenüberwacher for reporting the left position, a Weichenüberwacher for reporting the legal situation and a Weichenüberwacher for reporting the Auffahrung, the four limit switches of the switch are supplied with a monitoring voltage and the four limit switches of the switch accordingly the position of the four limit switches of the switch generate an excitation voltage and one of the three points monitor by mirroring the monitoring voltage supply, which generates the message about the order of the switch or the Auffahrmeldung and to a Datenverarbe conveying device for their preparation and / or further processing, wherein the points monitor for Generation of Auffahrmeldung two mutually poled and supplied with a monitoring voltage with a negative polarity optocoupler includes and wherein the four limit switches of the switch according to their position reflect the monitoring voltage with a positive polarity between terminals U and W of the switch and an excitation voltage to the points monitor to its activation and thus create generation of Auffahrmeldung, a structurally simple and easy to implement, also particularly efficient and reliable circuit achieved in total. Of particular advantage in practice has the Weichenüberwacher to generate the Auffahrmeldung with two mutually poled and supplied with a monitoring voltage with a negative polarity optocoupler on the one hand and the return reflection of the monitoring voltage with an exclusively positive polarity between the connection points on the other hand proved. On the one hand, the point monitor for generation of the ramp-up message during operation has a very low susceptibility to error and thus high reliability. On the other hand, in this way it is additionally possible to easily and quickly detect any fault or even any slight irregularity in the line of the monitoring circuit according to the invention, to recognize it as such and to turn it off, without any special design measures. Along with this, the costs, in particular for the production thereof, can be considerably reduced compared with circuits known in the prior art. Furthermore, the circuit according to the invention allows a start-up message based on a voltage monitoring (+60 V or +48 V instead of 0 V), which tolerates a wide range of values and can also be operated with a stamped current of 30 mA. All these advantages also far outweigh the fact that the circuit according to the invention can be used without external voltage detection for reasons of safety only for short positioning and monitoring distances of up to about 200 m. All the more so because recently it is increasingly observed that a signal box not as before with a central control, but with a decentralized and locally-based control is provided. As a rule, only positioning and monitoring distances of less than 100 m, typically even only about 10 m, between the signal box and the switch are to be bridged anyway.

Further particularly advantageous details of the circuit according to the invention for monitoring limit switches of a 4-wire three-phase drive of a switch and for generating a message about the current order position of the switch or a Auffahrmeldung are described in claims 2 to 9.

Fig. 1

eine schematische Darstellung einer Ausführungsform einer erfindungsgemäß ausgebildeten Schaltung zur Überwachung von Endlagenschaltern eines 4-Draht- Drehstrom-Antriebs einer Weiche und zur Generierung einer Meldung über die aktuelle Ordnungslage der Wei- che oder einer Auffahrmeldung, in der Ordnungslage bzw. im Normalfall einer ordentlichen Weichenendlage "Rechts",

Fig. 2

eine schematische Darstellung der Ausführungsform der erfindungsgemäß ausgebildeten Schaltung nach der Fig. 1, in der Ordnungslage bzw. im Normalfall einer ordentlichen Weichenendlage "Links",

Fig. 3

eine schematische Darstellung der Ausführungsform ei- ner erfindungsgemäß ausgebildeten Schaltung nach der Fig. 1, in der Stellung bzw. im Sonderfall der aufgefahrenen Weiche "Aufgefahren" bzw. "Umlaufend",

Fig. 4

eine Funktionsschema der Ausführungsform der erfin- dungsgemäß ausgebildeten Schaltung nach den Fig. 1 bis 3,

Fig. 5

eine schematische Darstellung des Zustandes der End- lagenschalter der Ausführungsform der erfindungsgemäß ausgebildeten Schaltung nach der Fig. 2 in der Ord- nungslage "Links",

Fig. 6

eine schematische Darstellung des Zustandes der End- lagenschalter der Ausführungsform der erfindungsgemäß ausgebildeten Schaltung nach der Fig. 1, in der Ord- nungslage "Rechts", und

Fig. 7

eine schematische Darstellung des Zustandes der End- lagenschalter der Ausführungsform der erfindungsgemäß ausgebildeten Schaltung nach der Fig. 3, in der Stel- lung "Aufgefahren" bzw. "Umlaufend".

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and examples of the invention and from the drawing. Showing:

Fig. 1

a schematic representation of an embodiment of an inventive circuit designed to monitor limit switches of a 4-wire three-phase drive a switch and to generate a message about the current order of the Weichen or a Auffahrmeldung, in the order situation or in the normal case a proper turnout end position "Right",

Fig. 2

a schematic representation of the embodiment of the invention formed according to the circuit Fig. 1 , in the order situation or in the normal case of a normal turnout end position "Links",

Fig. 3

a schematic representation of the embodiment of a inventively designed circuit according to the Fig. 1 , in the position or in special case of the ascended turnout "Aufgefahren" or "Umlaufend",

Fig. 4

a functional diagram of the embodiment of the invention formed according to the circuit Fig. 1 to 3 .

Fig. 5

a schematic representation of the state of the end position switch of the embodiment of the invention formed according to the circuit Fig. 2 in the order of "Links",

Fig. 6

a schematic representation of the state of the end position switch of the embodiment of the invention formed according to the circuit Fig. 1 , in the order situation "right", and

Fig. 7

a schematic representation of the state of the end position switch of the embodiment of the invention formed according to the circuit Fig. 3 , in the position "raised" or "circulating".

In the following description of an embodiment of a circuit 10 according to the invention for monitoring limit switches of a 4-wire three-phase drive of a switch and generating a message about the current order position of the switch or a Auffahrmeldung corresponding, identical components are each provided with identical reference numerals.

In the Fig. 1 to 3 an embodiment of a circuit 10 according to the invention is shown. In a 4-wire three-phase drive (not shown) of a switch (also not shown) four limit switches S1.1, S1.2, S2.1, S2.2 are installed. Of these, two limit switches S1.1, S1.2 of a switch point of the switch for left position and two limit switches S2.1, S2.2 assigned to a switch point of the switch for legal position. The Fig. 1 to 3 each differ in the position of the limit switches S1.1, S1.2, S2.1, S2.2 of the switch, as will be explained in more detail below.

The limit switches S1.1, S1.2, S2.1, S2.2 detect in pairs antivalent the position of the switch point of a switch. Accordingly, one switch is always closed for a regulatory position and one switch is opened while the other switch pair behaves in the opposite direction.

The limit switches S1.1, S1.2, S2.1, S2.2 of the circuit 10 are arranged in a monitoring in a current branch, over which their end position can be tested. The monitoring takes place in the circuit 10 according to the invention by means of a monitoring voltage U _ÜW in the form of a short-circuit-proof DC voltage. As monitoring voltage U _ÜW , a DC voltage of approximately between +48 V and +60 V inclusive is provided, and more particularly of +48 V or +60 V is preferred. In addition, an essentially constant current of 30 mA is advantageously used for the monitoring.

The monitoring _voltage U _ÜW is fed to the connection points V and Mp of the switch. Via the limit switches S1.1, S1.2 S2.1, S2.2 this voltage U _{ÜW is} mirrored onto the connection points U and W depending on the position of the switch. The polarity of the mirrored voltage is in the circuit 10 of the invention Fig. 1 to 3 by means of a simple voltage detection via a points monitor WÜL or WÜL.1, WÜL.2 for reporting the left position, a points monitor WÜR or WÜR.1, WÜR.2 for reporting the legal situation and a points monitor WÜA or WÜA.1, WÜA. 2 recorded to report the Auffahr.

The turnout monitor WÜL or WÜL.1, WÜL.2 for reporting the left position and the turnout monitor WÜR or WÜR.1, WÜR.2 for reporting the legal situation are each designed as optocouplers. The point monitor for generating the approach message WÜA or WÜA.1, WÜA.2 comprises two mutually poled and supplied with a monitoring voltage U _ÜW with a negative polarity optocoupler. Optocouplers provide one each complete potential separation between monitoring circuit and evaluation logic safe.

Although the circuit 10 according to the invention is potential-controlled, the circuit 10 is indeed relatively susceptible to interference voltages. In that regard, a use of the circuit according to the invention due to safety regulations on control and monitoring distances of up to about 200 m is limited. However, the advantage resulting from the circuit 10 according to the invention all outweighs this limitation, as already explained at the outset, since in the case of decentralized interlockings the distance to the outside element is small. [LG1]

In general, the monitoring _voltage U _{ÜW is mirrored} in an order position or in a normal case of a proper turnout end position by the limit switches S1.1, S1.2, S2.1, S2.2 such that a potential difference or excitation voltage at the turnout monitors WÜL. 1, WÜL.2, WÜR.1, WÜR.2, WÜA.1, WÜA.2 is present. Thus, the turnout monitors WÜL.1, WÜL.2, WÜR.1, WÜR.2, WÜA.1, WÜA.2 generate a 2-channel turnout end position to the signal box.

According to the Fig. 1 the switch is in the order position or in the normal case of a normal turnout end position "right". In the order position "right" the limit switches S1.1, S2.2 are closed and the limit switches S1.2, S2.1 are open. The connection point U of the switch now carries a positive voltage, since the limit switch S1.1 reproduces the supplied monitoring voltage U _ÜW of the connection point V of the switch. The negative voltage potential of the connection point Mp of the switch is reproduced by the limit switch S2.2 to the connection point W of the switch. Via the connection points U and W of the turnout, the turnout monitors WOR.1 and WÜR.2 are thus operated in the forward direction with the excitation voltage, which thus signal the legal position WÜR (turnout monitor right) of the turnout to the interlocking.

According to the Fig. 2 , in which an inverse voltage situation is shown, the switch is in the order position or in the normal case a proper turnout end position "left". In the "left" position, the limit switches S1.1, S2.2 are open and the limit switches S1.2, S2.1 are closed. The connection point U carries a negative voltage, since the limit switch S1.2 reproduces the supplied monitoring voltage U _ÜW from the connection point Mp. The positive voltage potential from the connection point V is reproduced at W by the limit switch S2.1. Via the connection points U and W, the turnout monitors WÜL.1 and WÜL.2 are thereby operated in the forward direction with the excitation voltage, which thus signal the left-hand position WÜL (turnout monitoring link) of the turnout to the interlocking.

According to the Fig. 3 the switch is in the position or in the special case of an ascended switch "raised" or "circulating", wherein the switch point of the switch assumes a position deviating from an end position or one of the two order positions "left" or "right" the position "Aufgefahren" is due to the limit switches S1.1 and S2.1 only positive voltage potential at the connection points U and W. Accordingly, the limit switches S1.1, S2.1 are closed and are the limit switches S1.2, S2.2 The connection points U and W each carry a positive voltage, since the limit switches S1.1, S2.2 reproduce the fed-in voltage from the connection point V. The exciter voltage is applied via the internal connection of the turnout monitors WÜA.1 and WÜA.2 Turnout monitors WÜA.1 and WÜA.2 constructed in this way, and a 2-channel Auffahrmeldung or message about the Auffahrlage or circulation position WÜA (WeichenÜberwacherAufgefahr en) of the switch to the signal box.

Such Auffahrmeldung, as by the invention Circuit 10 in the Fig. 3 shown schematically, never or only very rarely activated in normal operation. However, since the ramp-up message is of high security relevance, a corresponding test or a corresponding check is carried out randomly and / or cyclically at predetermined time intervals in order to trigger the ramp-up message. For this purpose, the line at the connection point Mp of the turnout is simulated interrupted by another optocoupler WA test (WeichenAuffahrTest). As a result, only positive potential is present at the connection points U, V and W and a positive exciter voltage can thus be developed at the turnout monitors WÜA.1 and WÜA.2. Then the order message disappears; the ramp-up message is triggered.

In the circuit 10, based on the Fig. 1 to 3 is explained in more detail, the three points monitor WÜL.1, WÜL.2 or WÜR.1, WÜR.2 or WÜA.1, WÜA.2 are each formed in pairs.

The turnout monitors WÜL.1, WÜL.2 or WÜR.1, WÜR.2 to report the left position or to report the legal situation, which each include an optocoupler, are each connected in series to each other.

The turnout monitors WÜA.1, WÜA.2 for generating a Auffahrmeldung, each comprising two mutually poled and supplied with a monitoring voltage U _ÜW with a negative polarity optocouplers are each arranged parallel to each other.

Such a duplication results for safety reasons in order to provide a 2-channelity of the respective turnout monitors WÜL.1, WÜL.2 or WÜR.1, WÜR.2 or WÜA.1, WÜA.2. This ensures that a first error is already revealed when one of the points monitor WÜL.1, WÜL.2 or WÜR.1, WÜR.2 or WÜA.1, WÜA.2 fails, for example as a result of alloy.

In the following, the operating principle of the circuit 10 based on Fig. 4 to 7 explained in detail, wherein the embodiment of the circuit 10, in the Fig. 4 to 7 is shown and described, only only one turnout monitor WÜL, WÜR, WÜA has.

In the situation monitoring, a monitoring _voltage U _ÜW of, for example, +48 V or +60 V at the connection points V and Mp of the points drive is fed. For the DC voltage, the drive coils are virtually absent, since the ohmic resistance of the winding is about 11 to 13 Ω - this can be neglected in comparison to the internal resistance of the optocouplers of about 2kΩ. Depending on the position of the limit switches, a + 60V potential of different polarity is detected at the connection points U and W.

In the upper half of the Fig. 4 is a functional diagram of the circuit 10 according to the invention for monitoring the four limit switches of the 4-wire three-phase drive of the switch shown. The circuit 10 comprises rectifier diodes GD, which select the polarity of the reflected exciter voltage and, depending on the switch configuration, supply the exciter voltage to one of the three switch monitors WÜL, WÜR, WÜA. The turnout monitors WÜL, WÜR, WÜA in turn generate the corresponding message on the secondary side, be it about the current order situation "left" or "right" of the turnout, be it about an approach position.

In the following Fig. 5 to 7 three typical states of the four limit switches of the 4-wire three-phase drive of the switch and thus the 4-wire three-phase drive of the switch itself are shown. In addition, for each of the states, the current flow for the monitoring is highlighted in bold. Dominates a regulatory situation, as from the FIGS. 5 and 6 shows, the limit switches S1.1, S1.2, S2.1, S2.2 are completely contrary to the order situation "right" for a regulatory situation "links".

In the Fig. 5 is an order situation "links" the switch illustrated. The monitoring _voltage U _ÜW , which is fed to the connection points V and Mp is reflected back with a negative polarity at the terminals or terminals U and W and an excitation voltage is generated, which causes excitation of the points monitor WÜL (WeichenÜberwacherLinks).

In the Fig. 6 is a regulatory situation "right" illustrates the switch. The monitoring voltage U _ÜW , which is fed in at the connection points V and Mp, is reflected back with a positive polarity at the connection points or terminals U and W and an excitation voltage is generated, which causes an excitation of the points monitor WÜR (switch monitor-right).

In the Fig. 7 Finally, a position "Aufgefahren" or "circulating" the switch is illustrated. In other words, in this case / these cases, the switch assumes no order which, for safety reasons, must be recognized promptly and reliably.

If a switch reaches its new end position, ie one of the two order positions "Left" or "Right", then only one pair S1.1, S1.2 or S2.1, S2.2 of the limit switches S1.1, S1. 2, S2.1, S2.2 changed his position. Of the Fig. 6 can be taken that in this constellation at the two connection points U and W or terminals a positive monitoring potential is applied. In this case, the current flow reaches the AND connection in each case and the excitation voltage or the counterpotential of the excitation voltage is applied to the point monitor WÜA (WeichenÜberwacherAufgefahren). If this state is detected after switching over the switch with the monitoring switched back on, this means that the switch has not reached the new end position. It can then be prompted, for example, a reversing. Will this condition on the other hand spontaneously reached during a turnout in the "left" or "right" position, so there is a departure of the switch.

In both cases the turnout monitor WÜA is activated. It is in the logic of the signal box to recognize whether it is a turnout not reached the new end position or an up-driven turnout to forward a message to the data processing device and to generate, for example, a corresponding display on an operator terminal.

Like that Fig. 4 to 7 In addition, the circuit 10 additionally comprises four rectifier diodes GD in order to select the reflected-back monitoring voltage U _ÜW and / or the generated counter potential of the monitoring voltage Usw.

The present invention is not limited to the illustrated embodiments of the circuit 10 according to the invention. Thus, it is readily possible, instead of the monitoring _voltage U _ÜW of, for example, +48 V or +60 V to feed a lower monitoring voltage of, for example, +24 V at the connection points V and Mp of the points drive, whereby the function of the circuit 10 according to the invention is not changed , It is likewise conceivable, instead of the monitoring _voltage U _ÜW of, for example, +48 V or +60 V to supply a negative monitoring voltage of, for example, -48 V or -60 V at the connection points V and Mp of the point machine. Only the voltage and current conditions are reversed when the optocouplers of the turnout monitors WÜL, WÜL.1, WÜL.2, WÜR, WÜR.1, WÜR.2, WÜA, WÜA.1, WÜA.2 receive a correspondingly changed polarity.

Claims (9)

1. Circuit element for monitoring terminal position switches of a 4-wire three-phase drive of a rail switch and for generating a notification about the current order position of the rail switch or a points trailed indication, which comprises four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch, two of which (S1.1, S1.2) are allocated to a switch tongue of the rail switch for the left-hand position and two of which (S2.1, S2.2) are allocated to a switch tongue of the rail switch for right-hand position, and a rail switch monitor to report the left-hand position (WÜL; WÜL.1, WÜL.2), a rail switch monitor to report the right-hand position (WÜR; WÜR.1, WÜR. 2) and a rail switch monitor to report trailing (WÜA; WÜA.1, WUA.2), whereby the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch are supplied by a supervisory voltage (U_ÜW) and whereby the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch according to the position of the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch generate an excitation voltage and conduct it to one of the three rail switch monitors (WÜL, WÜR, WÜA; WÜL.1, WÜL.2, WÜR.1, WÜR.2, WUA.1, WUA.2) through mirroring of the supervisory voltage (U_ÜW), which then generates the report about the order position of the rail switch or the points trailed indication and transfers it to a data processing center for further processing, characterized thereby that the rail switch monitor to generate the points trailed indication (WÜA; WÜA.1, WOA.2) comprises two optocouplers oppositely polarized and supplied by a supervisory voltage (U_ÜW) with a negative polarity and that the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch according to their position re-mirror the supervisory voltage (U_ÜW) with a positive polarity between connector points (U) and (W) of the rail switch and apply excitation voltage to the rail switch monitor (WÜA; WÜA.1, WÜA.2) in order to activate it and thus to generate the points trailed indication.
2. Circuit according to claim 1, characterized thereby that the rail switch monitor to report the left-hand position (WÜL; WÜL.1, WÜL.2) and the rail switch monitor to report the right-hand position (WÜR; WÜR.1, WÜR.2) each comprise an optocoupler and that the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch according to their position re-mirror the supervisory voltage (U_ÜW) with a negative polarity between the connector points (U) and (W) of the rail switch and apply excitation voltage to the rail switch monitor to report the left-hand position (WÜL; WÜL.1, WÜL.2) or the rail switch monitor to report the right-hand position (WÜR; WÜR. 1, WÜR.2) in order to activate it and to generate the report of left-hand or right-hand position of the rail switch tongue.
3. Circuit according to claim 1 or 2, characterized thereby that the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch according to their position generate a positive counterpotential to the supervisory voltage (U_ÜW) and apply the positive counterpotential as excitation voltage through a AND-conjunction to the two optocouplers of the rail switch monitor polarized opposite to each other (WÜA; WÜA.1, WÜA.2) in order to activate it.
4. Circuit according to one of the claims 1 to 3, characterized thereby that the circuit (10) comprises another optocoupler (WA-Test) at which in the event of coincidental or cyclic interruption of the negative supply of the supervisory voltage (U_ÜW) a positive counterpotential of the supervisory voltage (U_ÜW) as excitation voltage is applied to the two optocouplers of the rail switch monitor polarized opposite to each other (WÜA; WÜA.1, WÜA.2) in order to activate it.
5. Circuit according to one of the claims 1 to 4, characterized thereby that two rail switch monitors for generating the points trailed indication (WÜA; WÜA.1, WUA.2) are provided, each with two optocouplers polarized opposite to each other and supplied with supervisory voltage (U_ÜW) with negative polarity, which are arranged parallel to each other.
6. Circuit according to one of the claims 1 to 5, characterized thereby that two rail switch monitors for reporting the left-hand position (WÜL; WÜL.1, WÜL.2) with one optocoupler each and/or two rail switch monitors for reporting the right-hand position (WÜR; WÜR.1, WÜR.2) with one optocoupler each are provided, which are arranged in series to each other.
7. Circuit according to one of the claims 1 to 6, characterized thereby that the circuit will feature four rectifier diodes (GD) for selecting the re-mirrored supervisory voltage (U_ÜW) and/or the generated counterpotential of the supervisory voltage (U_ÜW).
8. Circuit according to one of the claims 1 to 7, characterized thereby that the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch as supervisory voltage (U_ÜW) are supplied with a direct-current voltage of between approximately +48 V and +60 V including, particularly of +48 V or +60 V.
9. Circuit according to one of the claims 1 to 8, characterized thereby that the four terminal position switches (S1.1, S1.2, S2.1, S2.2) of the rail switch are supplied with an essentially constant power supply of 30 mA.

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