Title of Invention	CIRCUIT FOR CONTROLLING & MONITORING RAILWAY SWITCH MECHANISMS
Abstract	The circuit according to the invention is split into a circuit section for actuating current connection and into a circuit section for monitoring the respective drive position. The drive motor is supplied from a single-phase or multi-phase AC mains power supply; two DC sources (U3, U4) are provided for supplying the sensors (Ml, M2) for monitoring the respective drive position. The two DC sources are connected by different poles to a common reference-earth potential, to which the AC supply voltage is also connected; this reference-earth potential also forms the reference-earth potential for the sensors. The monitoring voltages are routed via drive contacts (AK1 to AK4). to the sensors, the installation of separate switching links (Bl to B6) between the two circuit sections being required when the drive contacts are included in the supply circuits. The circuit according to the invention can be used in conjunction with any desired railway switch control circuits.

Title of Invention

CIRCUIT FOR CONTROLLING & MONITORING RAILWAY SWITCH MECHANISMS

Abstract

The circuit according to the invention is split into a circuit section for actuating current connection and into a circuit section for monitoring the respective drive position. The drive motor is supplied from a single-phase or multi-phase AC mains power supply; two DC sources (U3, U4) are provided for supplying the sensors (Ml, M2) for monitoring the respective drive position. The two DC sources are connected by different poles to a common reference-earth potential, to which the AC supply voltage is also connected; this reference-earth potential also forms the reference-earth potential for the sensors. The monitoring voltages are routed via drive contacts (AK1 to AK4). to the sensors, the installation of separate switching links (Bl to B6) between the two circuit sections being required when the drive contacts are included in the supply circuits. The circuit according to the invention can be used in conjunction with any desired railway switch control circuits.

Full Text	-1A- Co-pending application numbers 235/CAL/97 filed on 11.2.1997 and 237/CAL/97 filed on 11.2-97 are hereby incorporated by reference. Application No. 235/CAL/97 provides a circuit for monitoring light signals such that it is possible instead of signalling relays to use conventional control relays which are to be selected exclusively in accordance with the electrical operating conditions, the required reliability and cost. Application No. 237/CAL/97 specifies a device for fail safe controlling and monitoring electric loads which manages specifically for fail safe control in rail transport without the signalling relays developed for that purpose and tried and tested per se. The relays/contacts replacing the signalling relays are to be selectable only in accordance with the electrical operating conditions, reliability and costs. The present invention relates to a circuit for controlling and monitoring railway switch mechanism. Such a circuit is disclosed in EP-0 0S2 739 Bl- A railway switch circuit is reported there, whose drive is supplied from a three-phase mains power supply. The monitoring of the respective drive position is carried out by D. C. monitors which are coupled to the supply lines. The railway switch monitors are switched off while the railway switch is moving. The known circuit is designed exclusively for railway switch mechanisms which are operated via -1B- four wires. The known circuit is not suitable for controlling and monitoring, for example, three-phase railway switch mechanism which are operated in a six-wire circuit, or for single—phase drives. Separate actuating and monitoring circuits must be designed in each case for such drive citcuits. The object of the present invention is to develop a circuit such that it can be used for any desired drive connections, the design, both in terms of the actuating current connection and the monitoring, always being intended to be the same. Such a circuit would have the major advantage that it can be used for any desired drive type. This object is achieved by the circuit of the present invention. Actuating section modules, which are designed in a standard manner and are matched to the respective application by switching links, are used for the actuating current supply to the railway switch drives, and for monitoring it. Advantageous refinements and developments of the circuit according to the invention are described hereinafter. The invention will be explained in more detail in - 2 - the following text with reference to exemplary embodiments which are illustrated in the drawing, in which: Figure 1 shows a schematic illustration of the splitting of the circuit into a control-ler assembly and a monitor assembly, Figure 2 shows the specific refinement of the circuit for a railway switch mechanism which is operated with four wires, Figures 3 to 7 show the layout of the monitoring circuits which are formed in the various switching phases, Figure 8 shows a truth table for the monitoring signals from the sensors, Figures 9 to show the monitoring circuits for a railway 12 switch mechanism which is operated with six wires, and Figure 13 shows the specific refinement of the circuit for a single-phase drive which is operated via seven wires. The contacts, which are controlled by relays or ' contactors, are designated in the drawing by the reference characters for this relay or this contactor and by a sequential number following an oblique slash. The circuit according to the invention, in its physically structural configuration, is part of an actuating section module SM. It is split into a controller assembly SB and a Monitor assembly UB; the two assemblies are connected to one another. The actuating section module SM connects the railway switch mechanism WA to the power supply SV and to a controlling and monitoring computer system RS. Power is supplied from an AC mains power supply with an earth reference; the railway switch mechanism WA is designed, for example, as a three-phase railway switch mechanism and is supplied via four wires. Contacts of actuating relays, which are not illustrated, and contacts of railway switch position relays are used, for example, to switch the supply lines through in the controller assembly SB. These relays are part of a relay drive system RA which receives its - 3 - control instructions from the computer channels Kl and K2 of the controlling and monitoring computer system RS. A DC supply GV is provided for the power supply for the actuating relays and railway switch position relays; a converter assembly GV supplies earth-related DC monitoring voltages. These are required in the monitoring assembly UB in order to produce feedback messages about the respective position of the railway switch mechanism. These state messages are converted in a signalling drive system MA into monitoring messages which are supplied to the two computer channels of the computer system RS and are assessed there. Connections, which are implemented by switching links B, between the controller assembly SB and the monitor assembly UB are provided for connecting supply potentials from the monitor assembly to the controller assembly and for transmitting monitoring potentials, which characterize the respective drive position, back from the controller assembly to the monitor assembly. As will be shown later, these switching links allow the respectively required relationships between the controller and monitor assembly to be switched; these relationships are governed by different railway switch mechanisms and different drive circuits. Figure 2 shows the specific embodiment of the circuit according to the invention in its application in a three-phase railway switch mechanism WA which is operated via four wires; the actuating voltage network is provided with an earth reference. The respective running direction of the drive is predetermined from a controlling computer system, using two channels, by switching a direction relay R or L, respectively, on or off, respectively, for one running direction or the other, respectively. In the illustrated exemplary embodiment, it is assumed that the railway switch is located in the positive position, the switching means in the circuit assuming the switch positions illustrated in. Figure 2. Two sensors Ml, M2, which are indicated only schematically and carry a signalling potential at one of two inputs when the input potential (monitoring poten- - 4 - tial) is sufficiently high, are provided for monitoring the railway switch position; such sensors have been disclosed in conjunction with the monitoring of light signals, for example in DE 35 16 612 C2. The signalling potentials which are connected by one or the other output of the two sensors are phased into signalling messages MKl, MK2 at mutually corresponding points, and are transmitted to the two computer channels of the assessing computer system. The arrangement is in this case designed such that the two sensors Ml, M2 always carry signalling potentials at different outputs, and are connected to the two computer channels when the drive is correctly in the limit position, the connection to one or the other output depending on whether the railway switch is located in the positive or negative position. Only in the case of irregularities, specifically if the railway switch is positioned incorrectly or in the event of other defects, for example if any individual contacts which are connected in the actuating circuit of the railway switch mechanism assume an incorrect switch position, do the two sensors carry a signalling potential of the same polarity at the mutually corresponding outputs, or neither carry any signalling potential, which is then used for defect identification by the assessing computer system (see Figure 8). Two separate DC sources Ul, U2 are provided for supplying power to the sensors, Further DC sources U3, U4 are used to provide the monitoring potentials for controlling the sensors Ml, M2. The monitoring potentials are supplied to the sensors via drive contacts, The positive pole and the negative pole of the two DC sources U3, U4 are connected to earth via a separate line, each. The common earth forms the reference-earth potential for the two sensors; this is routed to the sensors via separate lines. The use of separate lines from the DC sources U3, U4 and the sensors Ml, M2 to the common reference-earth potential allows any line discontinuities to the reference-earth potential to be identified reliably. The common reference-earth potential of the DC - 5 - sources U3, U4 and of the sensors Ml, M2 is the same as that which is also used for the actuating current supply. The signalling potentials which are derived by the sensors from the monitoring potentials supplied to them are assessed by the computers only when the drive is switched off during operation. If, as a result of a defect, for example contact welding, one or more of the actuating wires were still to be connected through to the drive when the drive is switched off, then the actuating voltage would be superimposed on the monitoring potential, which is connected from the drive side, and would lead to at least one of the sensors not carrying any signalling potential on any of its outputs. The assessing computers would then identify this as a defect (earth-short message) , and would react to this in a predetermined manner. In the drive limit position illustrated, the positive potential of the monitoring voltage, which is provided from the DC source U3, is connected via the motor winding W3, the drive contact AK4 and the winding Wl to that signal input of the sensor Ml which is not connected to earth, and the negative potential of the DC source U4 is connected via the drive contact AK1 and the winding W2 to that signal input of the sensor M2 which is not connected to earth. The sensor Ml thus carries the signalling potential on its positive output, and the sensor M2 carries the signalling potential on its negative output. The signalling potentials of the two sensors are in each case contained in bit position 0 of the two signalling messages MK1, MK2 . In the other railway switch limit position, the sensors would occupy bit position 1 in the signalling messages with their signalling potentials. The assessing computer system uses the signalling potentials supplied to it on two channels to identify the respective drive position of the railway switch mechanism monitored by it. In the following text, it is assumed that it is intended to move the railway switch to the other position. The changeover is initiated by the computer system. - 6 - To do this, both computer channels work out appropriate control commands, independently of one another, for the direction relays R and L assigned to them. In this case, direction relay L is switched on by command K1K2 {Fig. 1) from the computer channel K2, and the direction relay R, which has been switched on until this point, is switched off via a command K1K1 from the computer channel Kl. The contacts of these relays at the same time change their switch position, the contacts R/l and L/l opening, and the contacts R/2, R/3 and L/2, L/3 closing. These contacts are located in the switch-on circuits of bistable position relays Rl, R2, L1, L2. The bistable position relays are used to preset the respective running direction by means of their contacts Rl/1, Ll/l, R2/1, L2/1 in the supply circuit of the drive motor; they are moved by switching supply voltages on temporarily. Each position relay has only a single switching contact as well as only a single setting winding. This means that the current direction into the position relay must be reversed in order to move the position relay into the other respective stable position. This is done in the present case by the contacts R/2, L/2 and R/3, L/3, or R/l, R/2. Two of the four position relays are in each case connected in series with one another, the arrangement being designed such that either the two position relays Rl and R2 are switched to the active position and the two position relays LI and L2 to the basic position, or vice versa, depending on whether the direction relay R or the direction relay L is switched on. The contacts of the position relays switch without any load. Instead of this, the supply lines are connected through to the railway switch mechanism via contacts Hll/1, H21/1, H12/1 and H22/1 of auxiliary contactors Hll to H22. These auxiliary contactors, two of which are in each case connected in series, are connected from one computer channel or the other, respectively, by appropriate commands K2K1 or K2K2, respectively (Fig. 2) , They are in each case connected in conjunction with the movement of the direction and position relays. To this - 7 - end, the two computer channels briefly forcibly trip switches S1, S2 which are connected in series with the auxiliary contactors; the switches are then held via a running current monitor LU, which will be explained later. The supply is in this case produced, as before, from the two computer channels, which can thus cancel the connection of the auxiliary contactors at any time. The contacts of the auxiliary contactors are arranged in the supply circuits of the drive motor such that these supply circuits are produced only when auxiliary contactors which are operated from different computer channels have pulled in, that is to say both computer channels carry out the connection. Reference is made to the schematic illustrations in Figures 3 to 7 in order to explain the processes during connection, movement and monitoring of the railway switch mechanism after reaching the new limit position. Figure 3 shows the situation at the start of the actuating process when the drive is being started; the drive contacts AK1 to AK4 have not yet changed in this case. A first circuit is produced via the contacts H11/1, Ll/1, the winding W2, the drive contact AK1 and the contact H22/1, and a second circuit is produced via the contacts H21/1, the winding W3, the drive contact AK4, the winding Wl, the contact L2/1 and the contact H12/1. Positive and negative monitoring potentials, respectively, which are supplied to the sensors Ml and M2 have the actuating voltage superimposed on them. For this reason, the signalling potentials from the sensors Ml, M2 are not assessed by the computer system while the railway switch is moving. The computer system identifies the necessity for assessment or non-assessment of the signalling potentials for example from the monitoring messages from the running current monitor LU, which has already been mentioned. Figure 4 shows the supply circuits during movement and after starting of the drive. The drive contacts AK1 and AK3 have changed; the drive is now running connected in star. A first circuit is closed via Hll/1, - 8 - Ll/1, the winding W2, AK3, the winding W3 and H21/1, and the second circuit is closed via H12/1, L2/1, the winding - Wl, the drive contact AK4, the winding W3 and H21/1. The signalling potentials from the sensors Ml, M2 are not assessed, as before. Figure 5 shows the railway switch circuit at the time at which the drive reaches the negative limit position. In this case, the drive contacts AK2 and AK4 have changed. The running current monitor cancels the control voltage for the switches S1, S2, and thus causes the auxiliary contactors to be disconnected. The signalling potentials are still not assessed, because the monitoring potentials have the AC supply voltage superimposed on them since the connection contacts are still closed. In Figure 6, the contacts of the auxiliary contactors have interrupted the power supply to the drive after the opening of the switches SI, S2 and after said auxiliary contactors have been disconnected as a result of this. The signalling potentials can be and now are assessed again by the computer system. The positive potential of the DC source U3 is connected to the sensor M2 via W3, AK3 and W2, and the negative potential of the DC source U4 is connected to the sensor Ml via AK2 and Wl. The computer system uses the signalling potentials which can be picked off at the outputs of the sensors to identify the current state of the drive. For reasons of completeness, it is intended in the following text to explain the production of the monitoring messages when the drive moves incorrectly out of the limit position assumed in Figure 6. The connection, which has existed until now, between the negative pole of the DC source U4 and the sensor Ml is interrupted via the contact AK2 which changes in the event of incorrect movement. At the same time, the positive potential from the DC source U3 is connected ' to the sensor Ml via the drive contact AK4, which is likewise changed over, and is also connected to the sensor M2 via the drive contact AK3. The assessing computer system uses - 9 - the presence of the same output signals from the two sensors to identify that a defect has occurred, and is thus able to react to this defect in a suitable manner. Corresponding processes also result if the drive moves from the negative position into the positive position and in the event of incorrectly moving from the positive position. Figure 8 uses a truth table to show the signalling potentials from the sensors Ml, M2, which result from the individual drive positions. The design and operation of the moving current monitor L0 will be explained in more detail in the following text, The running current monitor LU {Figure 2) essentially comprises a transformer having the two primary windings Tl, 1 and Tl, 2, and the secondary winding T2 . The two primary windings have the same number of turns; however, they are connected such that the supply currents which flow in them produce mutually opposing magnetic fields. As long as the drive is moving, supply currents which are phase-shifted through 120° flow through the two primary windings. This therefore produces on the secondary winding of the running current monitor a voltage which is sufficient to keep the switches S1, S2, which are connected in series with the auxiliary contactors, in the closed position while the railway switch is moving. When the new limit position is reached, the same supply current flows in opposite directions through the primary windings of the running current monitor, however, so that the voltage on the secondary winding of the transformer falls to the value zero. The running current monitor then opens the switches S1 and S2 in the supply circuit of the auxiliary contactors and thus, via their contacts, indirectly interrupts the further power supply to the railway switch mechanism. For the situation in which, for whatever reason, the running current monitor were not to open the switches S1, S2 at the correct time, separate time switch functions are assigned to the two computer channels and - 10 - disconnect the supply voltage for the auxiliary contactors in the event of a defect. The time monitoring is started when an actuating process starts, and is stopped after a maximum drive running time, which is predetermined for the railway switch movement, has elapsed. For switching extremely high-power drives, it is possible to operate further contactors first of all via the auxiliary contactors, and their contacts then switch the supply circuits of the drive. In the exemplary embodiment in Figure 2, which has a three-phase motor which is operated via four wires, there are a total of six switching links Bl to B6 via which the interaction between the circuit section for the actuating current connection and the circuit section for the monitoring is accomplished. The switching links are positioned such that the relationships which are listed in Patent Claim 1 are realized between the actuating and monitoring functions. Different switching links have to be inserted to ensure the intended relationships for railway switch mechanisms which are operated via other control circuits. This will be explained in the following text with reference to a further exemplary embodiment, the drive in this case being a three-phase drive which is to be operated via a total of six supply lines. Instead of six links, only four have to be provided, to be precise the links B3 to B6; the links Bl and B2 are omitted because the lines no longer need to be used more than once for the railway switch mechanism, because of the greater number of wires. Figure 9 shows the railway switch mechanism in the limit position, in which the associated railway switch assumes the positive position. The supply circuit is disconnected and the following monitoring circuits are formed: positive potential of the test voltage source U3, windings Wl and W3, drive contact AK8, Ml; negative potential of the test voltage source U4, drive contact AK6, M2. The assessing computer system uses the potentials supplied to it to identify the current state of the 11 railway switch mechanism. Figure 10 shows the state of the supply circuits at the start of the railway switch movement. The supply circuits which are illustrated by thicker lines in Figure 10 are formed after the position relays have changed over and the auxiliary contactors have been connected. The interlinked phase voltages are in each case applied to the windings Wl and W3 as well as W2 and W3; the drive starts to rotate. In doing so, the drive contacts AK5 and AK6 (not illustrated) change to the other position, in preparation for the further reconnection of the drive. The monitoring potentials have the actuating voltage superimposed on them; the computer system ignores the output potentials from the two sensors. As soon as the drive has reached the new limit position, the drive contacts AK7 and AK8 in Figure 11 have also changed. In consequence, the actuating circuits for the three motor windings are disconnected. The running current monitor {Figure 2)» which until this time has been activated via the supply current flowing in the line L2, opens the switches S1, S2 in the supply circuit of the auxiliary contactors Hll to H22 and thus ensures, by opening the contacts of these contactors in the supply circuit of the motor windings, that the drive is switched off and cannot move again until the two computers in the computer system cause the drive to be switched on again. When the actuating voltage is switched off, the computer system once again assesses the output potentials from the two sensors Ml, M2. The positive potential of the DC source U3 is supplied to the sensor M2, and the negative potential of the DC source U4 is supplied to the sensor Ml. Both pass the appropriate messages to the assessing computer system using two channels, and the computer system uses these messages to identify that the drive has correctly reached the negative limit position. Figure 12 shows the layout of the monitoring circuits when the railway switch has moved incorrectly, it being assumed that the railway switch was previously in the positive position. When the railway switch moves 12 incorrectly, the contacts AK5 and AK6 have changed. The positive pole of the DC source U3 is connected via the windings W2 and Wl as well as the drive contact AKS to the signal input of the sensor M2, and via the windings W2 and W3 and the drive contact AK8 to the signal input of the sensor Ml, The assessing computer system uses the application of the positive signalling potential to the two computer channels to identify that the defect has occurred, and issues an appropriate defect message. Processes corresponding to those which have been explained with reference to Figures 8 to 11 also take place when the railway switch changes from the negative position to the positive position or the railway switch moves incorrectly out of the negative position; the truth table according to Figure 8 also applies to the railway switch mechanism considered above and operated with six wires. Figure 13 shows the circuit according to the invention in its application with a single-phase drive motor M, It is assumed that the railway switch which is controlled by the drive is located in the positive position. In this case, the positive potential passes from the DC source U3 via the drive contact AK1 to the signal input of the sensor Ml, and the negative potential passes from the DC source U4 via the drive contact AK4 to the signal input of the sensor M2. If it is now intended to reverse the railway switch, then the computer system initially causes' the direction relay R to be switched off and the direction relay L to be switched on, their contacts in the supply circuit of the bistable position relays Rl, R2, LI, L2. changing. When the supply voltage is briefly switched on, the position relays L1 and L2 move to their active position, and the position relays Rl and R2 move to their basic position. The contact Rl/l of the position relay Rl opens without any load, while the contact Ll/Ll of the position relay Ll closes without any load; the two contacts govern the running direction of the drive motor when the actuating voltage is switched on. The bistable 13 position relays maintain their respective operating state even after their supply voltage has been switched off. Following the reversal of the position relays, the computer system causes the auxiliary contactors H11 to H22 to be switched on by briefly turning on the switches S1 and S2, which are connected in series with the auxiliary contactors, for example via an auxiliary capacitor. When an actuating current now flows, following the closing of the connection contacts Hll/l and H22/1 which are controlled by the contactors, the running current monitor LU takes over the further supply of the switches S1 and S2. The drive now moves, the drive contacts AK2 and AK4 changing first of all. The two sensors Ml and M2 now carry potential at their positive output, but this is not assessed by the computer system because of the actuating voltage which is coupled into the monitoring circuit. When the new limit position is reached, the drive contacts AK1 and AK3 also change. The negative potential of the DC source U4 is now connected via AK3 to the signal input of the sensor Ml, and the positive potential of the DC source U3 is connected via AK2 to the signal input of the sensor M2. When the new limit position is reached, the drive contacts AK11 and AK12 also change, the drive contact AK12 interrupting the supply circuit for the motor winding M and thus also switching the running current monitor such that it is not live. Via the switches SI and S2 this causes the auxiliary contactors to be disconnected and thus makes the joint involvement of the computer system necessary in order to switch the motor on again. The drive contact AKll closes in, preparation for subsequent movement of the railway switch in the other direction. As the above statements have shown, the design of the actuating section module, which comprises a controller assembly and a monitor assembly, is always the same irrespective of the number of wires which are used to operate a railway switch mechanism motor. Routing the inputs and outputs of the monitor assembly and of the controller assembly out of the actuating section module - 14 - makes it possible, if necessary, for these inputs and outputs to be electrically conductively connected to one another by means of links, and thus makes it possible to produce the respectively desired interaction between the two assemblies. The connections must in this case be switched such that the monitoring potentials are routed via the motor-controlled drive contacts to the sensors such that the latter actually emit the required signalling voltages at the railway switch positions which are to be detected. The circuit according to the invention can therefore be used for any commercially available drive type, irrespective of the number of supply lines used to supply it with the actuating power. The contacts of four auxiliary contactors are used for connecting through and disconnecting the supply circuits for the drive motor. If one of the contacts remains stuck in the open position, for example because an auxiliary contactor can no longer be connected, then, as a rule, the drive will no longer reach its new limit position within the permissible movement time. With the disconnection of the auxiliary contactors, the assessing computer system identifies the fault which has occurred, since at least one of the sensors does not carry any potential on the output side. If the contact of one of the auxiliary contactors remains stuck in the closed position, for example because it is welded, then the signal input of at least one of the sensors is at the common reference-earth potential of the sensors and of the actuating current supply for the drive; a corresponding defect message is produced. Even if, as a result of a faulty drive, with only one channel, of in each case two auxiliary contactors whose contacts in the supply circuit of the drive close, this can be identified by the computer system since both the sensors are at the reference-earth potential on the input side, and the signalling potential thus remains absent from both outputs of the sensor. The contacts of the auxiliary contactors are connected into the supply circuits of the drive motor - 15 - such that it is not possible for any actuating current to flow at all and for the drive to move unless both computer channels have passed appropriate switch-on commands to the auxiliary contactors, and both computer channels are connected through. As a result of the continuous monitoring of the switching state of the drive contacts, it is possible to design them in electronic form. Any malfunctions of such electronic switches are detected via the sensors and are identified by the computer system as a defect. Faults in the running current monitoring are identified by the computer system during the next movement by the running current message not occurring at the correct time or remaining absent. Particularly where the monitoring potentials do not have any actuating voltages superimposed on them during the railway switch movement, it is possible to dispense with running current monitoring on the computer side in order to identify a new drive limit position if, instead of this, the computer system continuously - that is to say throughout the railway switch movement as well - detects the signalling potentials from the sensors. The computer system can use the occurrence of quite specific combinations of signalling potentials to deduce that a new limit position has been reached, and to derive from this the necessity of continuing to monitor the drive limit position. Faults at the interface from the computer in the direction of control of the actuating section (permanent or missing relay drives) act like faults in the relays or their contacts and are thus covered as described above. In the direction of messages to the computer, faults (absent or permanent messages) are evident as messages not included in the signalling scheme. Series-path resistances up to discontinuity or short circuits may be regarded as wire shorts in the cable system to the drive. Series-path resistances beyond a specific value are identified by switching off the message or if the motor no longer starts, runs too long - 16 - or does not reach the limit position. If they have appropriate low impedance, wire shorts trip actuating voltage protection devices during the changeover process and, in addition, lead to the messages being turned off in the event of shorts of wires at a different signalling voltage potential, wires shorts of wires at the same signalling potential are identified after the next changeover process. Polarity reversals in the three-phase mains power supply from the actuating mechanism supply are identified by faulty, that is to say unexpected, messages during the next changeover process. As a result of the changeover of the position relays for the reversal, the lines of changed polarity are connected to the wires to the drive in the same phase as for the previous movement. The motor runs in the coupling, and the messages do not change, because the drive contacts do not change. In the exemplary embodiments which have been explained above, the output voltages which are switched by the running current monitor are used not only to close and open the switches S1, S2; they also inform the evaluating computer system of the necessity of assessing or not assessing the sensor output signals (during the railway switch changeover). An advantageous modification of the device explained above provides for the output voltage of the running current monitor to' act directly on the sensors and to switch its inputs or outputs to be inactive during the railway switch movement, for example via blocking elements; any influence on the computer system is then superfluous. - 17 - 1. Circuit for controlling and monitoring railway-switch mechanisms using switching means, which can be set such that they interact, in the supply lines to preset the respective running direction of the drive, and having circuit breaking means, which are connected in series with them, in all the supply lines to switch the actuating current on and off, and having DC monitoring, which assesses the switch position of drive contacts, in order to identify the respective drive position, characterized in that, to identify the respective drive positions two sensors (Ml, M2) are provided which respond to different potentials, are monitored jointly and are at a common reference-earth potential for the sensors and the actuating current supply, in that two DC sources (U3, U4) are provided for supply-ing the sensors, one (U3) of which is connected to one pole (-) and the other of which (U4) is connected to the other pole (+) on the common reference-earth potential of the sensors, and in that the respectively other poles of the two DC sources and of the two sensors are routed indirectly via supply lines, through which current passes when the drive is moving, to the drive contacts (AK1 to AK4) , the two sensors in each case being connected between one or the other drive contact pair (AK2, AK4 or AK1, AK3, respectively) which can be moved jointly while the drive is moving and are in each case adjacent, and the two DC sources in each case being connected between the one or the other drive contact pair (AK4, AK3 or AK2, AK1, respectively) which can be moved successively while the drive is moving and are in each case adjacent, in that the circuit is split into an actuating current section (SB), which accommodates at least the switching means (Rl/1, Ll/1, R2/l, L2/1) for presetting the respective running direction and the circuit breaking means (Hll/1, H12/1, H21/1, H22/1), and into a monitoring - 18 - section (UB) which accommodates at least the sensors (Ml, M2), the inputs and outputs of which sections are routed independently of one another out of an actuating section module (SM) which contains both circuit sections, and in that the outputs of the two circuit sections are connected by switching links (Bl to B6) in order to produce the abovementioned relationships between the actuating and monitoring function for all drive modes which arise. 2. Circuit according to Claim 1, wherein the circuit breaking means can be operated from different computer channels of a controlling computer system, the channel allocation being made such that circuit breakers (Hll/1, H22/1; H12/1, H21/1) , which are in each case controlled from different channels, are arranged in the supply lines {LI, L2, L3, N) which are connected via the motor windings (Wl, W2, W3), and actuating current can flow only when both computer .' channels have been jointly involved with switching the supply circuits through. 3. Circuit according to Claim 2, wherein contactors (Hll, H12, H21, H22) are provided for controlling the circuit breaking means, and in that switches {S1, S2) are arranged in the supply circuits of these contactors, can be temporarily connected from the computer channels of the controlling computer system and, in doing so, operate the contactors, and in that a running current monitor (LU) is provided, in conjunction with the switches, in order to detect the progressive forced tripping of the switches, which running current, monitor (LU) detects the actuating current, switches the switches off on reaching the new limit position of the drive - controlled by at least one drive contact (AK3) -and disconnects the supply circuit of the circuit breakers. 4. Circuit according to Claim 3, wherein the running current monitor (LU) is represented - 19 - by a transformer, through whose at least one primary winding (Tl, Tl.l, Tl.2) actuating current, which flows via at least one motor winding and at least one drive contact, flows when the drive is moving, and whose secondary winding (T2) in this case makes available a control and supply voltage which is used to control the switches (S1, S2). 5. Circuit according to Claim 4, wherein the transformer has two primary windings (Tl.l, Tl.2), one (Tl.2) of which is connected in the common return conductor (N) of the motor windings, and the other is connected between the circuit breaking means (H12/1) and the switching means (L2/l, R2/1) for presetting the direction in that input conductor (L2) which is connected to the return conductor (N) via the drive contacts (AK2; AK1) on reaching the new limit position, and in that the two primary windings (Tl.l, Tl.2) form mutually opposing magnetic fields, of equal magnitude, via the supply current which then flows. 6. Circuit according to one of Claims l to 5, wherein a time switch is provided which can be set at the start of each movement and disconnects the switches when a maximum permissible movement time for the railway switch movement elapses. ?. Circuit according to Claim 1 or 5, wherein the switching means (Rl/1, R2/1, Ll/1, L2/1) can be controlled at least indirectly by relays (R, L) in order to preset the respective running direction of the drive, which relays (R, L) can be operated from different computer channels of a controlling computer system. 8. Circuit according to Claim 7, wherein the switching means for presetting the respective running direction of the drive are represented by the contacts of bistable relays (Rl, R2, LI, L2) each having only a single winding, and in that the connection of - 20 - these bistable relays takes place via relays (R, L) which are controlled from both computer channels, such that the current direction in the bistable relays in each case reverses when the running direction of the drive is reversed. 9. Circuit according to Claim 2, wherein the circuit breakers are represented by the contacts (Hll/1, H12/1, H21/1, H22/1) of contactors (Hll, H12, H21, H22), or by electronic switches. 10. Circuit according to Claim 9, wherein that each contactor has only a single switching contact, and in that at least two contactors (Hll, H12; H21, H22) can in each case be connected from the same computer channel. 11. Circuit according to Claim 1, wherein the DC sources (U3, U4) and the sensors (Ml, M2) are each connected via separate lines to the common reference-earth potential. 12. Circuit according to Claim 1, wherein the computer channels do not assess the signal potentials, which are offered to them from the sensors (Ml, M2), while the railway switch is moving. 13. Circuit according to Claims 3 and 12, wherein the computer channels identify the necessity to assess signal potentials from the presence/absence of the running current monitoring. 14 Circuit according to Claim 1, wherein the computer system continuously detects the signal potentials of the sensors (Ml, M2) and uses the occurrence of preset signal potentials on both sensors to identify that the new limit position has been reached, and thus the necessity for drive monitoring. 15. Circuit according to Claims 1 to 3, - 21 - wherein the output voltage of the running current monitor acts on the sensors and switches their inputs or outputs to be ineffective while the railway switch is moving. The circuit according to the invention is split into a circuit section for actuating current connection and into a circuit section for monitoring the respective drive position. The drive motor is supplied from a single-phase or multi-phase AC mains power supply; two DC sources (U3, U4) are provided for supplying the sensors (Ml, M2) for monitoring the respective drive position. The two DC sources are connected by different poles to a common reference-earth potential, to which the AC supply voltage is also connected; this reference-earth potential also forms the reference-earth potential for the sensors. The monitoring voltages are routed via drive contacts (AK1 to AK4). to the sensors, the installation of separate switching links (Bl to B6) between the two circuit sections being required when the drive contacts are included in the supply circuits. The circuit according to the invention can be used in conjunction with any desired railway switch control circuits.

Full Text

-1A-
Co-pending application numbers 235/CAL/97 filed on 11.2.1997 and 237/CAL/97 filed on 11.2-97 are hereby incorporated by reference.
Application No. 235/CAL/97 provides a circuit for monitoring light signals such that it is possible instead of signalling relays to use conventional control relays which are to be selected exclusively in accordance with the electrical operating conditions, the required reliability and cost.
Application No. 237/CAL/97 specifies a device for fail safe controlling and monitoring electric loads which manages specifically for fail safe control in rail transport without the signalling relays developed for that purpose and tried and tested per se. The relays/contacts replacing the signalling relays are to be selectable only in accordance with the electrical operating conditions, reliability and costs.
The present invention relates to a circuit for controlling and monitoring railway switch mechanism. Such a circuit is disclosed in EP-0 0S2 739 Bl- A railway switch circuit is reported there, whose drive is supplied from a three-phase mains power supply. The monitoring of the respective drive position is carried out by D. C. monitors which are coupled to the supply lines. The railway switch monitors are switched off while the railway switch is moving. The known circuit is designed exclusively for railway switch mechanisms which are operated via

-1B-
four wires. The known circuit is not suitable for controlling and
monitoring, for example, three-phase railway switch mechanism which are operated in a six-wire circuit, or for single—phase drives. Separate actuating and monitoring circuits must be designed in each case for such drive citcuits.
The object of the present invention is to develop a circuit such that it can be used for any desired drive connections, the design, both in terms of the actuating current connection and the monitoring, always being intended to be the same. Such a circuit would have the major advantage that it can be used for any desired drive type.
This object is achieved by the circuit of the present invention. Actuating section modules, which are designed in a standard manner and are matched to the respective application by switching links, are used for the actuating current supply to the railway switch drives, and for monitoring it.
Advantageous refinements and developments of the circuit according to the invention are described hereinafter.
The invention will be explained in more detail in

- 2 -
the following text with reference to exemplary embodiments which are illustrated in the drawing, in which: Figure 1 shows a schematic illustration of the
splitting of the circuit into a control-ler assembly and a monitor assembly, Figure 2 shows the specific refinement of the circuit for a railway switch mechanism which is operated with four wires, Figures 3 to 7 show the layout of the monitoring circuits which are formed in the various switching phases, Figure 8 shows a truth table for the monitoring
signals from the sensors,
Figures 9 to show the monitoring circuits for a railway
12 switch mechanism which is operated with
six wires, and Figure 13 shows the specific refinement of the circuit for a single-phase drive which is operated via seven wires. The contacts, which are controlled by relays or ' contactors, are designated in the drawing by the reference characters for this relay or this contactor and by a sequential number following an oblique slash.
The circuit according to the invention, in its physically structural configuration, is part of an actuating section module SM. It is split into a controller assembly SB and a Monitor assembly UB; the two assemblies are connected to one another. The actuating section module SM connects the railway switch mechanism WA to the power supply SV and to a controlling and monitoring computer system RS. Power is supplied from an AC mains power supply with an earth reference; the railway switch mechanism WA is designed, for example, as a three-phase railway switch mechanism and is supplied via four wires. Contacts of actuating relays, which are not illustrated*, and contacts of railway switch position relays are used, for example, to switch the supply lines through in the controller assembly SB. These relays are part of a relay drive system RA which receives its

- 3 -
control instructions from the computer channels Kl and K2 of the controlling and monitoring computer system RS. A DC supply GV is provided for the power supply for the actuating relays and railway switch position relays; a converter assembly GV* supplies earth-related DC monitoring voltages. These are required in the monitoring assembly UB in order to produce feedback messages about the respective position of the railway switch mechanism. These state messages are converted in a signalling drive system MA into monitoring messages which are supplied to the two computer channels of the computer system RS and are assessed there. Connections, which are implemented by switching links B, between the controller assembly SB and the monitor assembly UB are provided for connecting supply potentials from the monitor assembly to the controller assembly and for transmitting monitoring potentials, which characterize the respective drive position, back from the controller assembly to the monitor assembly. As will be shown later, these switching links allow the respectively required relationships between the controller and monitor assembly to be switched; these relationships are governed by different railway switch mechanisms and different drive circuits.
Figure 2 shows the specific embodiment of the circuit according to the invention in its application in a three-phase railway switch mechanism WA which is operated via four wires; the actuating voltage network is provided with an earth reference. The respective running direction of the drive is predetermined from a controlling computer system, using two channels, by switching a direction relay R or L, respectively, on or off, respectively, for one running direction or the other, respectively. In the illustrated exemplary embodiment, it is assumed that the railway switch is located in the positive position, the switching means in the circuit assuming the switch positions illustrated in. Figure 2. Two sensors Ml, M2, which are indicated only schematically and carry a signalling potential at one of two inputs when the input potential (monitoring poten-

- 4 -
tial) is sufficiently high, are provided for monitoring the railway switch position; such sensors have been disclosed in conjunction with the monitoring of light signals, for example in DE 35 16 612 C2. The signalling potentials which are connected by one or the other output of the two sensors are phased into signalling messages MKl, MK2 at mutually corresponding points, and are transmitted to the two computer channels of the assessing computer system. The arrangement is in this case designed such that the two sensors Ml, M2 always carry signalling potentials at different outputs, and are connected to the two computer channels when the drive is correctly in the limit position, the connection to one or the other output depending on whether the railway switch is located in the positive or negative position. Only in the case of irregularities, specifically if the railway switch is positioned incorrectly or in the event of other defects, for example if any individual contacts which are connected in the actuating circuit of the railway switch mechanism assume an incorrect switch position, do the two sensors carry a signalling potential of the same polarity at the mutually corresponding outputs, or neither carry any signalling potential, which is then used for defect identification by the assessing computer system (see Figure 8).
Two separate DC sources Ul, U2 are provided for supplying power to the sensors, Further DC sources U3, U4 are used to provide the monitoring potentials for controlling the sensors Ml, M2. The monitoring potentials are supplied to the sensors via drive contacts, The positive pole and the negative pole of the two DC sources U3, U4 are connected to earth via a separate line, each. The common earth forms the reference-earth potential for the two sensors; this is routed to the sensors via separate lines. The use of separate lines from the DC sources U3, U4 and the sensors Ml, M2 to the common reference-earth potential allows any line discontinuities to the reference-earth potential to be identified reliably. The common reference-earth potential of the DC

- 5 -
sources U3, U4 and of the sensors Ml, M2 is the same as that which is also used for the actuating current supply. The signalling potentials which are derived by the sensors from the monitoring potentials supplied to them are assessed by the computers only when the drive is switched off during operation. If, as a result of a defect, for example contact welding, one or more of the actuating wires were still to be connected through to the drive when the drive is switched off, then the actuating voltage would be superimposed on the monitoring potential, which is connected from the drive side, and would lead to at least one of the sensors not carrying any signalling potential on any of its outputs. The assessing computers would then identify this as a defect (earth-short message) , and would react to this in a predetermined manner.
In the drive limit position illustrated, the positive potential of the monitoring voltage, which is provided from the DC source U3, is connected via the motor winding W3, the drive contact AK4 and the winding Wl to that signal input of the sensor Ml which is not connected to earth, and the negative potential of the DC source U4 is connected via the drive contact AK1 and the winding W2 to that signal input of the sensor M2 which is not connected to earth. The sensor Ml thus carries the signalling potential on its positive output, and the sensor M2 carries the signalling potential on its negative output. The signalling potentials of the two sensors are in each case contained in bit position 0 of the two signalling messages MK1, MK2 . In the other railway switch limit position, the sensors would occupy bit position 1 in the signalling messages with their signalling potentials. The assessing computer system uses the signalling potentials supplied to it on two channels to identify the respective drive position of the railway switch mechanism monitored by it.
In the following text, it is assumed that it is intended to move the railway switch to the other position. The changeover is initiated by the computer system.

- 6 -
To do this, both computer channels work out appropriate control commands, independently of one another, for the direction relays R and L assigned to them. In this case, direction relay L is switched on by command K1K2 {Fig. 1) from the computer channel K2, and the direction relay R, which has been switched on until this point, is switched off via a command K1K1 from the computer channel Kl. The contacts of these relays at the same time change their switch position, the contacts R/l and L/l opening, and the contacts R/2, R/3 and L/2, L/3 closing. These contacts are located in the switch-on circuits of bistable position relays Rl, R2, L1, L2. The bistable position relays are used to preset the respective running direction by means of their contacts Rl/1, Ll/l, R2/1, L2/1 in the supply circuit of the drive motor; they are moved by switching supply voltages on temporarily. Each position relay has only a single switching contact as well as only a single setting winding. This means that the current direction into the position relay must be reversed in order to move the position relay into the other respective stable position. This is done in the present case by the contacts R/2, L/2 and R/3, L/3, or R/l, R/2. Two of the four position relays are in each case connected in series with one another, the arrangement being designed such that either the two position relays Rl and R2 are switched to the active position and the two position relays LI and L2 to the basic position, or vice versa, depending on whether the direction relay R or the direction relay L is switched on.
The contacts of the position relays switch without any load. Instead of this, the supply lines are connected through to the railway switch mechanism via contacts Hll/1, H21/1, H12/1 and H22/1 of auxiliary contactors Hll to H22. These auxiliary contactors, two of which are in each case connected in series, are connected from one computer channel or the other, respectively, by appropriate commands K2K1 or K2K2, respectively (Fig. 2) , They are in each case connected in conjunction with the movement of the direction and position relays. To this

- 7 -
end, the two computer channels briefly forcibly trip switches S1, S2 which are connected in series with the auxiliary contactors; the switches are then held via a running current monitor LU, which will be explained later. The supply is in this case produced, as before, from the two computer channels, which can thus cancel the connection of the auxiliary contactors at any time. The contacts of the auxiliary contactors are arranged in the supply circuits of the drive motor such that these supply circuits are produced only when auxiliary contactors which are operated from different computer channels have pulled in, that is to say both computer channels carry out the connection.
Reference is made to the schematic illustrations in Figures 3 to 7 in order to explain the processes during connection, movement and monitoring of the railway switch mechanism after reaching the new limit position.
Figure 3 shows the situation at the start of the actuating process when the drive is being started; the drive contacts AK1 to AK4 have not yet changed in this case. A first circuit is produced via the contacts H11/1, Ll/1, the winding W2, the drive contact AK1 and the contact H22/1, and a second circuit is produced via the contacts H21/1, the winding W3, the drive contact AK4, the winding Wl, the contact L2/1 and the contact H12/1. Positive and negative monitoring potentials, respectively, which are supplied to the sensors Ml and M2 have the actuating voltage superimposed on them. For this reason, the signalling potentials from the sensors Ml, M2 are not assessed by the computer system while the railway switch is moving. The computer system identifies the necessity for assessment or non-assessment of the signalling potentials for example from the monitoring messages from the running current monitor LU, which has already been mentioned.
Figure 4 shows the supply circuits during movement and after starting of the drive. The drive contacts AK1 and AK3 have changed; the drive is now running connected in star. A first circuit is closed via Hll/1,

- 8 -
Ll/1, the winding W2, AK3, the winding W3 and H21/1, and the second circuit is closed via H12/1, L2/1, the winding - Wl, the drive contact AK4, the winding W3 and H21/1. The signalling potentials from the sensors Ml, M2 are not assessed, as before.
Figure 5 shows the railway switch circuit at the time at which the drive reaches the negative limit position. In this case, the drive contacts AK2 and AK4 have changed. The running current monitor cancels the control voltage for the switches S1, S2, and thus causes the auxiliary contactors to be disconnected. The signalling potentials are still not assessed, because the monitoring potentials have the AC supply voltage superimposed on them since the connection contacts are still closed.
In Figure 6, the contacts of the auxiliary contactors have interrupted the power supply to the drive after the opening of the switches SI, S2 and after said auxiliary contactors have been disconnected as a result of this. The signalling potentials can be and now are assessed again by the computer system. The positive potential of the DC source U3 is connected to the sensor M2 via W3, AK3 and W2, and the negative potential of the DC source U4 is connected to the sensor Ml via AK2 and Wl. The computer system uses the signalling potentials which can be picked off at the outputs of the sensors to identify the current state of the drive.
For reasons of completeness, it is intended in the following text to explain the production of the monitoring messages when the drive moves incorrectly out of the limit position assumed in Figure 6. The connection, which has existed until now, between the negative pole of the DC source U4 and the sensor Ml is interrupted via the contact AK2 which changes in the event of incorrect movement. At the same time, the positive potential from the DC source U3 is connected ' to the sensor Ml via the drive contact AK4, which is likewise changed over, and is also connected to the sensor M2 via the drive contact AK3. The assessing computer system uses

- 9 -
the presence of the same output signals from the two
sensors to identify that a defect has occurred, and is thus able to react to this defect in a suitable manner.
Corresponding processes also result if the drive moves from the negative position into the positive position and in the event of incorrectly moving from the positive position.
Figure 8 uses a truth table to show the signalling potentials from the sensors Ml, M2, which result from the individual drive positions.
The design and operation of the moving current monitor L0 will be explained in more detail in the following text,
The running current monitor LU {Figure 2) essentially comprises a transformer having the two primary windings Tl, 1 and Tl, 2, and the secondary winding T2 . The two primary windings have the same number of turns; however, they are connected such that the supply currents which flow in them produce mutually opposing magnetic fields. As long as the drive is moving, supply currents which are phase-shifted through 120° flow through the two primary windings. This therefore produces on the secondary winding of the running current monitor a voltage which is sufficient to keep the switches S1, S2, which are connected in series with the auxiliary contactors, in the closed position while the railway switch is moving. When the new limit position is reached, the same supply current flows in opposite directions through the primary windings of the running current monitor, however, so that the voltage on the secondary winding of the transformer falls to the value zero. The running current monitor then opens the switches S1 and S2 in the supply circuit of the auxiliary contactors and thus, via their contacts, indirectly interrupts the further power supply to the railway switch mechanism.
For the situation in which, for whatever reason, the running current monitor were not to open the switches S1, S2 at the correct time, separate time switch functions are assigned to the two computer channels and

- 10 -
disconnect the supply voltage for the auxiliary contactors in the event of a defect. The time monitoring is started when an actuating process starts, and is stopped after a maximum drive running time, which is predetermined for the railway switch movement, has elapsed.
For switching extremely high-power drives, it is possible to operate further contactors first of all via the auxiliary contactors, and their contacts then switch the supply circuits of the drive.
In the exemplary embodiment in Figure 2, which has a three-phase motor which is operated via four wires, there are a total of six switching links Bl to B6 via which the interaction between the circuit section for the actuating current connection and the circuit section for the monitoring is accomplished. The switching links are positioned such that the relationships which are listed in Patent Claim 1 are realized between the actuating and monitoring functions. Different switching links have to be inserted to ensure the intended relationships for railway switch mechanisms which are operated via other control circuits. This will be explained in the following text with reference to a further exemplary embodiment, the drive in this case being a three-phase drive which is to be operated via a total of six supply lines. Instead of six links, only four have to be provided, to be precise the links B3 to B6; the links Bl and B2 are omitted because the lines no longer need to be used more than once for the railway switch mechanism, because of the greater number of wires.
Figure 9 shows the railway switch mechanism in the limit position, in which the associated railway switch assumes the positive position. The supply circuit is disconnected and the following monitoring circuits are formed: positive potential of the test voltage source U3, windings Wl and W3, drive contact AK8, Ml; negative potential of the test voltage source U4, drive contact AK6, M2. The assessing computer system uses the potentials supplied to it to identify the current state of the

11
railway switch mechanism.
Figure 10 shows the state of the supply circuits at the start of the railway switch movement. The supply circuits which are illustrated by thicker lines in Figure 10 are formed after the position relays have changed over and the auxiliary contactors have been connected. The interlinked phase voltages are in each case applied to the windings Wl and W3 as well as W2 and W3; the drive starts to rotate. In doing so, the drive contacts AK5 and AK6 (not illustrated) change to the other position, in preparation for the further reconnection of the drive. The monitoring potentials have the actuating voltage superimposed on them; the computer system ignores the output potentials from the two sensors.
As soon as the drive has reached the new limit position, the drive contacts AK7 and AK8 in Figure 11 have also changed. In consequence, the actuating circuits for the three motor windings are disconnected. The running current monitor {Figure 2)» which until this time has been activated via the supply current flowing in the line L2, opens the switches S1, S2 in the supply circuit of the auxiliary contactors Hll to H22 and thus ensures, by opening the contacts of these contactors in the supply circuit of the motor windings, that the drive is switched off and cannot move again until the two computers in the computer system cause the drive to be switched on again. When the actuating voltage is switched off, the computer system once again assesses the output potentials from the two sensors Ml, M2. The positive potential of the DC source U3 is supplied to the sensor M2, and the negative potential of the DC source U4 is supplied to the sensor Ml. Both pass the appropriate messages to the assessing computer system using two channels, and the computer system uses these messages to identify that the drive has correctly reached the negative limit position.
Figure 12 shows the layout of the monitoring circuits when the railway switch has moved incorrectly, it being assumed that the railway switch was previously in the positive position. When the railway switch moves

12
incorrectly, the contacts AK5 and AK6 have changed. The positive pole of the DC source U3 is connected via the
windings W2 and Wl as well as the drive contact AKS to the signal input of the sensor M2, and via the windings W2 and W3 and the drive contact AK8 to the signal input of the sensor Ml, The assessing computer system uses the application of the positive signalling potential to the two computer channels to identify that the defect has occurred, and issues an appropriate defect message.
Processes corresponding to those which have been explained with reference to Figures 8 to 11 also take place when the railway switch changes from the negative position to the positive position or the railway switch moves incorrectly out of the negative position; the truth table according to Figure 8 also applies to the railway switch mechanism considered above and operated with six wires.
Figure 13 shows the circuit according to the invention in its application with a single-phase drive motor M, It is assumed that the railway switch which is controlled by the drive is located in the positive position. In this case, the positive potential passes from the DC source U3 via the drive contact AK1 to the signal input of the sensor Ml, and the negative potential passes from the DC source U4 via the drive contact AK4 to the signal input of the sensor M2.
If it is now intended to reverse the railway switch, then the computer system initially causes' the direction relay R to be switched off and the direction relay L to be switched on, their contacts in the supply circuit of the bistable position relays Rl, R2, LI, L2. changing. When the supply voltage is briefly switched on, the position relays L1 and L2 move to their active position, and the position relays Rl and R2 move to their basic position. The contact Rl/l of the position relay Rl opens without any load, while the contact Ll/Ll of the position relay Ll closes without any load; the two contacts govern the running direction of the drive motor when the actuating voltage is switched on. The bistable

13
position relays maintain their respective operating state even after their supply voltage has been switched off. Following the reversal of the position relays, the computer system causes the auxiliary contactors H11 to H22 to be switched on by briefly turning on the switches S1 and S2, which are connected in series with the auxiliary contactors, for example via an auxiliary capacitor. When an actuating current now flows, following the closing of the connection contacts Hll/l and H22/1 which are controlled by the contactors, the running current monitor LU takes over the further supply of the switches S1 and S2. The drive now moves, the drive contacts AK2 and AK4 changing first of all. The two sensors Ml and M2 now carry potential at their positive output, but this is not assessed by the computer system because of the actuating voltage which is coupled into the monitoring circuit. When the new limit position is reached, the drive contacts AK1 and AK3 also change. The negative potential of the DC source U4 is now connected via AK3 to the signal input of the sensor Ml, and the positive potential of the DC source U3 is connected via AK2 to the signal input of the sensor M2. When the new limit position is reached, the drive contacts AK11 and AK12 also change, the drive contact AK12 interrupting the supply circuit for the motor winding M and thus also switching the running current monitor such that it is not live. Via the switches SI and S2 this causes the auxiliary contactors to be disconnected and thus makes the joint involvement of the computer system necessary in order to switch the motor on again. The drive contact AKll closes in, preparation for subsequent movement of the railway switch in the other direction.
As the above statements have shown, the design of the actuating section module, which comprises a controller assembly and a monitor assembly, is always the same irrespective of the number of wires which are used to operate a railway switch mechanism motor. Routing the inputs and outputs of the monitor assembly and of the controller assembly out of the actuating section module

- 14 -
makes it possible, if necessary, for these inputs and outputs to be electrically conductively connected to one another by means of links, and thus makes it possible to produce the respectively desired interaction between the two assemblies. The connections must in this case be switched such that the monitoring potentials are routed via the motor-controlled drive contacts to the sensors such that the latter actually emit the required signalling voltages at the railway switch positions which are to be detected. The circuit according to the invention can therefore be used for any commercially available drive type, irrespective of the number of supply lines used to supply it with the actuating power.
The contacts of four auxiliary contactors are used for connecting through and disconnecting the supply circuits for the drive motor. If one of the contacts remains stuck in the open position, for example because an auxiliary contactor can no longer be connected, then, as a rule, the drive will no longer reach its new limit position within the permissible movement time. With the disconnection of the auxiliary contactors, the assessing computer system identifies the fault which has occurred, since at least one of the sensors does not carry any potential on the output side. If the contact of one of the auxiliary contactors remains stuck in the closed position, for example because it is welded, then the signal input of at least one of the sensors is at the common reference-earth potential of the sensors and of the actuating current supply for the drive; a corresponding defect message is produced. Even if, as a result of a faulty drive, with only one channel, of in each case two auxiliary contactors whose contacts in the supply circuit of the drive close, this can be identified by the computer system since both the sensors are at the reference-earth potential on the input side, and the signalling potential thus remains absent from both outputs of the sensor.
The contacts of the auxiliary contactors are connected into the supply circuits of the drive motor

- 15 -
such that it is not possible for any actuating current to flow at all and for the drive to move unless both computer channels have passed appropriate switch-on commands to the auxiliary contactors, and both computer channels are connected through.
As a result of the continuous monitoring of the switching state of the drive contacts, it is possible to design them in electronic form. Any malfunctions of such electronic switches are detected via the sensors and are identified by the computer system as a defect.
Faults in the running current monitoring are identified by the computer system during the next movement by the running current message not occurring at the correct time or remaining absent.
Particularly where the monitoring potentials do not have any actuating voltages superimposed on them during the railway switch movement, it is possible to dispense with running current monitoring on the computer side in order to identify a new drive limit position if, instead of this, the computer system continuously - that is to say throughout the railway switch movement as well - detects the signalling potentials from the sensors. The computer system can use the occurrence of quite specific combinations of signalling potentials to deduce that a new limit position has been reached, and to derive from this the necessity of continuing to monitor the drive limit position.
Faults at the interface from the computer in the direction of control of the actuating section (permanent or missing relay drives) act like faults in the relays or their contacts and are thus covered as described above.
In the direction of messages to the computer, faults (absent or permanent messages) are evident as messages not included in the signalling scheme.
Series-path resistances up to discontinuity or short circuits may be regarded as wire shorts in the cable system to the drive. Series-path resistances beyond a specific value are identified by switching off the message or if the motor no longer starts, runs too long

- 16 -
or does not reach the limit position.
If they have appropriate low impedance, wire shorts trip actuating voltage protection devices during the changeover process and, in addition, lead to the messages being turned off in the event of shorts of wires at a different signalling voltage potential, wires shorts of wires at the same signalling potential are identified after the next changeover process.
Polarity reversals in the three-phase mains power supply from the actuating mechanism supply are identified by faulty, that is to say unexpected, messages during the next changeover process. As a result of the changeover of the position relays for the reversal, the lines of changed polarity are connected to the wires to the drive in the same phase as for the previous movement. The motor runs in the coupling, and the messages do not change, because the drive contacts do not change.
In the exemplary embodiments which have been explained above, the output voltages which are switched by the running current monitor are used not only to close and open the switches S1, S2; they also inform the evaluating computer system of the necessity of assessing or not assessing the sensor output signals (during the railway switch changeover). An advantageous modification of the device explained above provides for the output voltage of the running current monitor to' act directly on the sensors and to switch its inputs or outputs to be inactive during the railway switch movement, for example via blocking elements; any influence on the computer system is then superfluous.

- 17 -
1. Circuit for controlling and monitoring railway-switch mechanisms using switching means, which can be set such that they interact, in the supply lines to preset the respective running direction of the drive, and having circuit breaking means, which are connected in series with them, in all the supply lines to switch the actuating current on and off, and having DC monitoring, which assesses the switch position of drive contacts, in order to identify the respective drive position, characterized
in that, to identify the respective drive positions two sensors (Ml, M2) are provided which respond to different potentials, are monitored jointly and are at a common reference-earth potential for the sensors and the actuating current supply, in that two DC sources (U3, U4) are provided for supply-ing the sensors, one (U3) of which is connected to one pole (-) and the other of which (U4) is connected to the other pole (+) on the common reference-earth potential of the sensors, and
in that the respectively other poles of the two DC sources and of the two sensors are routed indirectly via supply lines, through which current passes when the drive is moving, to the drive contacts (AK1 to AK4) , the two sensors in each case being connected between one or the other drive contact pair (AK2, AK4 or AK1, AK3, respectively) which can be moved jointly while the drive is moving and are in each case adjacent, and the two DC sources in each case being connected between the one or the other drive contact pair (AK4, AK3 or AK2, AK1, respectively) which can be moved successively while the drive is moving and are in each case adjacent, in that the circuit is split into an actuating current section (SB), which accommodates at least the switching means (Rl/1, Ll/1, R2/l, L2/1) for presetting the respective running direction and the circuit breaking means (Hll/1, H12/1, H21/1, H22/1), and into a monitoring

- 18 -
section (UB) which accommodates at least the sensors (Ml, M2), the inputs and outputs of which sections are routed independently of one another out of an actuating section module (SM) which contains both circuit sections, and in that the outputs of the two circuit sections are connected by switching links (Bl to B6) in order to produce the abovementioned relationships between the actuating and monitoring function for all drive modes which arise.
2. Circuit according to Claim 1,
wherein
the circuit breaking means can be operated from different computer channels of a controlling computer system, the channel allocation being made such that circuit breakers (Hll/1, H22/1; H12/1, H21/1) , which are in each case controlled from different channels, are arranged in the supply lines {LI, L2, L3, N) which are connected via the motor windings (Wl, W2, W3), and actuating current can flow only when both computer .' channels have been jointly involved with switching the supply circuits through.
3. Circuit according to Claim 2,
wherein
contactors (Hll, H12, H21, H22) are provided for controlling the circuit breaking means, and in that switches {S1, S2) are arranged in the supply circuits of these contactors, can be temporarily connected from the computer channels of the controlling computer system and, in doing so, operate the contactors, and in that a running current monitor (LU) is provided, in conjunction with the switches, in order to detect the progressive forced tripping of the switches, which running current, monitor (LU) detects the actuating current, switches the switches off on reaching the new limit position of the drive - controlled by at least one drive contact (AK3) -and disconnects the supply circuit of the circuit breakers.
4. Circuit according to Claim 3,
wherein
the running current monitor (LU) is represented

- 19 -
by a transformer, through whose at least one primary winding (Tl, Tl.l, Tl.2) actuating current, which flows via at least one motor winding and at least one drive contact, flows when the drive is moving, and whose secondary winding (T2) in this case makes available a control and supply voltage which is used to control the switches (S1, S2).
5. Circuit according to Claim 4,
wherein
the transformer has two primary windings (Tl.l, Tl.2), one (Tl.2) of which is connected in the common return conductor (N) of the motor windings, and the other is connected between the circuit breaking means (H12/1) and the switching means (L2/l, R2/1) for presetting the direction in that input conductor (L2) which is connected to the return conductor (N) via the drive contacts (AK2; AK1) on reaching the new limit position, and in that the two primary windings (Tl.l, Tl.2) form mutually opposing magnetic fields, of equal magnitude, via the supply current which then flows.
6. Circuit according to one of Claims l to 5,
wherein
a time switch is provided which can be set at the
start of each movement and disconnects the switches when a maximum permissible movement time for the railway switch movement elapses.
?. Circuit according to Claim 1 or 5, wherein the switching means (Rl/1, R2/1, Ll/1, L2/1) can be controlled at least indirectly by relays (R, L) in order to preset the respective running direction of the drive, which relays (R, L) can be operated from different computer channels of a controlling computer system.
8. Circuit according to Claim 7, wherein
the switching means for presetting the respective running direction of the drive are represented by the contacts of bistable relays (Rl, R2, LI, L2) each having only a single winding, and in that the connection of

- 20 -
these bistable relays takes place via relays (R, L) which are controlled from both computer channels, such that the current direction in the bistable relays in each case reverses when the running direction of the drive is reversed.
9. Circuit according to Claim 2,
wherein
the circuit breakers are represented by the contacts (Hll/1, H12/1, H21/1, H22/1) of contactors (Hll, H12, H21, H22), or by electronic switches.
10. Circuit according to Claim 9,
wherein
that each contactor has only a single switching contact, and in that at least two contactors (Hll, H12; H21, H22) can in each case be connected from the same computer channel.
11. Circuit according to Claim 1,
wherein
the DC sources (U3, U4) and the sensors (Ml, M2) are each connected via separate lines to the common reference-earth potential.
12. Circuit according to Claim 1,
wherein
the computer channels do not assess the signal potentials, which are offered to them from the sensors (Ml, M2), while the railway switch is moving.
13. Circuit according to Claims 3 and 12,
wherein
the computer channels identify the necessity to assess signal potentials from the presence/absence of the running current monitoring. 14 Circuit according to Claim 1,
wherein
the computer system continuously detects the signal potentials of the sensors (Ml, M2) and uses the occurrence of preset signal potentials on both sensors to identify that the new limit position has been reached, and thus the necessity for drive monitoring. 15. Circuit according to Claims 1 to 3,

- 21 -
wherein
the output voltage of the running current monitor
acts on the sensors and switches their inputs or outputs
to be ineffective while the railway switch is moving.
The circuit according to the invention is split into a circuit section for actuating current connection and into a circuit section for monitoring the respective drive position. The drive motor is supplied from a single-phase or multi-phase AC mains power supply; two DC sources (U3, U4) are provided for supplying the sensors (Ml, M2) for monitoring the respective drive position. The two DC sources are connected by different poles to a common reference-earth potential, to which the AC supply voltage is also connected; this reference-earth potential also forms the reference-earth potential for the sensors. The monitoring voltages are routed via drive contacts (AK1 to AK4). to the sensors, the installation of separate switching links (Bl to B6) between the two circuit sections being required when the drive contacts are included in the supply circuits. The circuit according to the invention can be used in conjunction with any desired railway switch control circuits.

Documents:

00236-cal-1997-abstract.pdf

00236-cal-1997-claims.pdf

00236-cal-1997-correspondence.pdf

00236-cal-1997-description(complete).pdf

00236-cal-1997-drawings.pdf

00236-cal-1997-form-1.pdf

00236-cal-1997-form-2.pdf

00236-cal-1997-form-3.pdf

00236-cal-1997-form-5.pdf

00236-cal-1997-g.p.a.pdf

00236-cal-1997-priority document others.pdf

00236-cal-1997-priority document.pdf

236-cal-1997-granted-abstract.pdf

236-cal-1997-granted-acceptance publication.pdf

236-cal-1997-granted-claims.pdf

236-cal-1997-granted-correspondence.pdf

236-cal-1997-granted-description (complete).pdf

236-cal-1997-granted-drawings.pdf

236-cal-1997-granted-form 1.pdf

236-cal-1997-granted-form 2.pdf

236-cal-1997-granted-form 3.pdf

236-cal-1997-granted-form 5.pdf

236-cal-1997-granted-gpa.pdf

236-cal-1997-granted-letter patent.pdf

236-cal-1997-granted-priority document.pdf

236-cal-1997-granted-reply to examination report.pdf

236-cal-1997-granted-specification.pdf

236-cal-1997-granted-translated copy of priority document.pdf

« Previous Patent

Next Patent »

Patent Number

193826

Indian Patent Application Number

236/CAL/1997

PG Journal Number

30/2009

Publication Date

24-Jul-2009

Grant Date

01-Apr-2005

Date of Filing

11-Feb-1997

Name of Patentee

SIEMENS AKTIENGESELLSCHAFT

Applicant Address

WITTELSBACHERPLATZ 2, 80333 MUNCHEN

Inventors:

#	Inventor's Name	Inventor's Address
1	JÜRGEN KLAUS	GERSTÄCKERSTRAßE 21, D-38102 BRAUNSCHWEIG

PCT International Classification Number

B61L 19/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	19606895.9	1996-02-13	Germany