Title of Invention

CIRCUIT FOR MONITORING LIGHT SIGNALS BY MEANS OF A SINGLE MONITOR

Abstract

Instead of signal relays, control relays (SO, S1) with non-mechanically coupled changeover contacts (SO/1, SO/2, Sl/1) are used to switch the signal lamps of a reliable light signal (LS). The control relays are designed mechanically such that should the individual changeover contacts be welded in one position they no longer change upon changeover of the relevant relay. The contacts are arranged in the supply leads to the signal lamps (LR, LG) such that mechanical fixing of one of the contacts is indicated by the next control operation at the latest during the stressing following the occurrence of this fault. This is brought about because the relevant signal lamp can no longer be switched on or that specific monitoring signals are lacking. The circuit according to the invention is intended, in particular, for controlling and monitoring light signals in rail transport.

Full Text

-1A- Co-pending application Nos. 236/CAL/97 and 237/CAL/97 both filed on February 11, 1997 are hereby incorporated by reference. Application No- 236/CAL/97 provides a circuit for controlling and monitoring railway switch mechanisms 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. 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/contactors 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 monitoring light [signals. Such a circuit is disclosed in DE-C 22 55 200. A circuit arrangement is disclosed there for relay-monitored circuits for detecting wire contacts, which manages with only a single monitoring relay for monitoring the stop signal lamps and proceed signal lamps of a light signal. In order to switch on the proceed signal lamp, two successively switchable actuators are provided, of which, when it is actuated, the one responding first -1B- disconnects the monitor relay switched into the stop, signal, circuit, and connects a voltage to the proceed signal loop, which is to be switched on, in a single-pole fashion via the winding of the monitor relay, which is still disconnected. The deliberate disconnection, of the monitor relay upon changing from the stop indication to a proceed indication subjects this monitor relay to a drop-out test. Shortly after the switching of the first actuatar, the second actuator also switches. By means of one contact, it interrupts the supply circuit, still closed up till now, for the stop signal lamp, and switches the second wire to the proceed signal lamp. In the case of a proper operating state of the light signal, the monitor relay now responds again, the flow direction in the monitor relay having changed as against that when the stop signal lamp is switched on. If the proceed signal circuit is in contact with a wire of the stop signal lamp at an arbitrary instant with the proceed signal lamp switched on, monitor relay drops out owing to a short circuit. In order to realise the abovementioned operating cycle, this known circuit depends on the contacts of the respective actuators switching at the same instant. This means that the actuators must be constructed as signalling relays with mechanically—coupled contacts. 2 It is the object of the present Invention to develop the known circuit 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. The invention achieves this object by the circuit of the present invention. Advantageous refinements and developments of the circuit according to the invention are described hereinafter. The invention is explained in more detail below with the aid of exemplary embodiments represented in the accompanying drawing, in which : Figure 1 shows the incorporation of the circuit according to the invention into the control and monitoring circuit of a light signal having a stop signal lamp and a proceed signal lamp; Figures 2 to 5 show representations of the circuit with in each case one switching contact, assumed to be welded and Figure 6 shows a light signal having a plurality of stop signal lamps and proceed signal lamps which are controlled and monitored by assigned signal modules of uniform construction. The light signal LS represented diagrammatically in Figure 1 is provided with a proceed signal lamp LG and a stop signal lamp LR, which can be switched on alternately by an interlocking cabin. For this purpose, the two signal lamps are connected to the indoor equipment of the interlocking cabin via diagrammatically indicated, also relatively long supply lines L1, L2. Acutators SO and S1 which can be connected alternately from the interlocking cabin are used in a way known per se in order to switch the signal lamps. The interlocking cabin is represented by a fait sage computer system of which one channel serves one actuator and the other channel serves.......... - 3 - the other actuator. The channel separation is illustrated in Figure 1 by a dotted line. Dashed lines indicate captive electrical isolation between the individual components of the circuit. In a departure from the prior art, the two actuators SO and S1 are constructed not as signalling relays with mechanically coupled contacts and break contacts, but as control relays with non-mechanically coupled changeover contacts SO/1 and SO/2 or Sl/1. They are designed mechanically such that should the individual changeover contacts weld in one position they can no longer change upon changeover of the relevant relay; the break contact remains closed and the make contact remains open; this means that in the event of a fault one of the considered changeover contacts is fixed mechanically, while the other changeover contact of the relay continues to operate properly. It is assumed in Figure 1 that the stop signal lamp LR of the light signal LS is switched on. The signal lamp is supplied from an alternating-source operated in a fashion free from earth. The supply current leads via the contact Sl/1, closed in the basic position of the actuator S1, of the actuator S1, the lines L2 to the stop signal lamp LR, the stop signal lamp LR, a monitor U switched into the supply circuit, and the contacts SO/2 and SO/1, closed in the basic position of the actuator S1, of the actuator SO. In this arrangement, a signalling "voltage which is fed via an optocoupler 0K3 for electrical isolation to a window discriminator FD for evaluation is generated in the monitor U via a resistor Rx. More detail will be given on this window discriminator later. It is assumed below that the light signal LS is to display the proceed indication. For this purpose, the controlling computer system firstly connects the actuator SO via one channel, and later connects the actuator S1 via the other channel. Upon connection of the actuator SO2its changeover contacts SO/1 and SO/2 change into the respective other switch position. In this case, tne two -4- switching contacts interrupt the supply circuit, led via the monitor U, for the stop signal lamp LR, which has so far been switched on and does not, however, go out because the supply continues to be maintained via the switching contact SO/1 bridging the switching contact SO/2 and the monitor U. However, the signalling voltage collapses across the resistor Rx, which is now short circuited, with the result that the monitoring device U changes into the de-energized state (drop-out test). The signal lamp LG is now switched on in a single-pole fashion via the contact SO/1, the resistor Rx and the contact SO/2. If, owing to a wire contact, for example with a wire leading to the stop signal lamp, or to coupled-in interference voltages, there is a back-voltage at this instant on one of the wires leading to the proceed signal lamp, a signalling voltage which is detected by the window discriminator would occur across the resistor Rx. Thereupon, the window discriminator transmits a corresponding monitoring signal to the evaluating computer system, which deduces a fault from the wrongly timed monitoring signal and thereupon causes a specific reaction, which can consist, inter alia, in disconnecting the actuator SO. In this case, the supply circuit, switched through in a single-pole fashion, to the proceed signal lamp LG is then opened, and the stop signal lamp LR is switched on again. If the abovementioned event of a fault does not occur, that is to say the monitor U has been subjected to a proper drop-out test after the connection of the actuator SO, the computer system also connects the actuator S1, with a delay, the changeover contact Sl/1 of said actuator S1 changing. In this process, the still existing stop signal circuit is opened, and the second wire to the proceed signal lamp LG is switched through. The supply and monitoring circuit for this signal lamp leads via the contact Sl/1, closed in the working position of the second actuator, of the actuator S1, the lines L1 and the signal lamp LG, the contact SO/2, closed in the working position of the first actuator, of the GR 96 P 4017 DE - 5 - actuator SO, the resistor Rx and the contact SO/1 of the first actuator. The use of control relays with non-mechanically coupled contacts can give rise to the case that the contacts controlled by the relay SO no longer operate synchronously. This is the case whenever one of the contacts SO/1, SO/2 welds. This contact is then fixed mechanically, while the other relay contact continues to operate properly. It is to be set forth below with the aid of Figures 2 to 5 what happens if one of the contacts is fixed in one or the other position; the relevant contact and its respective contact position are emphasized in the figures by thicker lines. The monitor U is illustrated symbolically by a relay winding. In the signalling module SM represented in Figure 2, it is assumed that the contact SO/1 of the actuator SO is welded in the position which it reached upon switching- on of the stop signal lamp LR. If the actuator SO for switching on the proceed signal position is connected, only the contact SO/2 changes. In this process, the supply circuit for the stop signal lamp LR, which has so far been switched on, is interrupted and the monitor U drops out (as expected) . When the actuator S1 is connected, its switching contact Sl/1 changes. In this process, the second wire to the stop signal lamp is also opened and, at the same time, the corresponding wire to the proceed signal lamp LG is switched through. However, the proceed signal lamp cannot light up, because the supply circuit is interrupted via the mechanically fixed contact SO/1 of the first actuator. The monitor U signals the operating state it has detected to the interlocking cabin, which is thus informed about the presence of a signal fault. It is assumed in Figure 3 that the same switching contact is fixed in the other position. In this position, the monitoring signal of the monitor U is absent, with the result that the interlocking cabin can deduce the fault which has occurred, and gives no proceed command to this signal. 6 In Figure 4, the changeover contact SO/2 of the first actuator is to be mechanically fixed in the position which is reached when the proceed signal lamp LG was switched on in a single-pole fashion. As a consequence of this, the corresponding monitoring signal of the monitor is lacking upon the later switching-off of the proceed signal lamp LG and the switching-on of the stop signal lamp LR; the interlocking cabin is informed of the occurrence of the fault by the missing monitoring signal. In Figure 5, the same switching contact is assumed to be permanently in the other position. It reaches this position when the proceed signal lamp LG is switched off. As a consequence for the assumed mechanical fixing of the contact SO/2, the proceed signal lamp is not switched on. The corresponding monitoring signal is lacking; the fault is therefore detectable. If the contact S1/1 welds in one or the other position, it prevents the stop signal lamp LR or the proceed signal lamp LG from being switched on. A corresponding monitoring signal from the monitor informs the interlocking cabin of the fault occurring. It has been demonstrated with the above assumptions that the claimed monitoring circuit with its non-mechanically coupled changeover contacts is equally as reliable as the circuit previously known from DE-C 22 55 200, in which signal relays with mechanically coupled break contacts and make contacts are used. A contact fault shows up at the latest during the stressing, following the occurrence of the fault, of the signal lamp in the operation of which the fault was produced. As already set forth, the lamp current flowing via the lamp filament respectively connected generates in a resistor Rx a signalling voltage which is connected via an optocoupler OK3 to a window discriminator FD. The mode of operation of this window discriminator is explained in detail in German Utility Model 94 11 807. The window discriminator is supplied with power from a direct-voltage source. The monitoring signal, that is to say - 7 - information as to whether the respectively detected lamp current is within prescribed tolerances or not, is transmitted via a further optocoupler OK1 to the evaluating computer system and processed there in two computer channels independently of one another. The window discriminator can be set to different operating points in order to monitor different current windows for day operation and night operation. This is performed via an optocoupler 0K2 to which appropriate control potentials can be fed from the interlocking cabin. The window discriminator can be subjected to a functional test by temporarily varying the operating points monitored by it, a check being made as to whether the lamp current flowing is within the current window for night operation or within the current window for day operation and has not migrated beyond the defined operating points. The optocouplers for captive electrical isolation of the circuit from the computer channels have a safety design. Earth faults in the light signal circuits operated in a fashion free from earth can be detected by an earth fault detector (not represented). Different lamp currents flow, depending on the lamp power of the signal lamps respectively used, different signalling voltages also occurring across the measuring shunt Rx. The measuring shunt Rx is of adjustable design in order to adjust these signalling voltages to a prescribed value identical for all lamp powers; the magnitude of said resistor decreases with increasing lamp power. It had been assumed in the exemplary embodiment of the circuit according to the invention which was explained in more detail above that the light signal to be controlled and to be monitored should have a stop signal lamp and a proceed signal lamp capable of being switched on alternately, and that a window discriminator is assigned to this light signal for the purpose of monitoring one or other of the lamp currents. In fact, however, light signals can have more than two signal lamps capable of being switched on alternately, in - 8 - parficular if these light signals comprise both main signals and distant signals. In order to keep the outlay for monitoring the lamp currents respectively flowing as low as possible, a development of the circuit according to the invention provides for feeding the signalling voltages of a multiplicity of signal lamps cyclically to a common window discriminator and storing the measured values respectively determined in the evaluating computer system until they are updated by new measurement results. It is to be ensured in this case by means of special circuit measures that the cyclic connection of the signalling voltages derived from different lamp currents actually does take place. According a preferred embodiment of the invention, the discriminator is to be used for cyclic monitoring of a total of four signalling submodules having in each case one or two signal lamps which can be switched on alternately. The wiring of such signalling submodules is represented in Figure 6. Each signalling submodule SMI to SM4 has the changeover contacts, already explained, S01/1, S01/2, S011/1; S02/1, S02/2, S012/1; S03/1, S03/2, S013/1; S04/1, S04/2, S014/1 of two control relays and an associated monitor Ul to U4, which is represented by the measuring shunts at which the signalling voltages, derived from the lamp currents, for the window discriminator can be tapped. The contacts of the control relays are denoted in the same way as those in Figure 1, merely supplemented by a serial number behind the designation of the respective control relay to which they belong. As is to be seen, a stop signal lamp LR1 and a proceed signal lamp LG1 are connected to the signalling submodule SM1, as is also the case in Figure 1. The signalling voltage to be evaluated can be uniquely assigned to one or the other of the signal lamps owing to the alternate switching on of one or other of the signal lamps. Only a single signal lamp LG2, LR2 and LG3 is respectively provided in the case of the remaining signalling submodules. Depending respectively on whether a proceed signal lamp or a stop signal lamp is involved - 9 - in this case, the supply leads to the signal lamps are connected to one or other of the pairs of output terminals of the relevant signalling submodule, specifically in exactly the same way as the signal lamps according to Figure 1. It is achieved thereby that it is always possible to have recourse to the same signalling sub-modules in order to control and monitor arbitrarily configured light signals. Each signalling submodule is capable of controlling and monitoring the respectively associated signal lamp or the associated signal lamps, conventional control relays having changeover contacts being used as switching means. Possible contact welds become noticeable at the latest when a control operation is initiated for which the contact weld previously occurred. With respect to the monitoring signals, the contact welds act in the same way as wire contacts between wires, at back-potential, of stop signal circuits and proceed signal circuits of the same light signal or different light signals. Instead of a controlling and monitoring interlocking cabin, it is also possible to provide another control and monitoring device, for example a computer system remote from the interlocking cabin. - 10 - Patent Claims 1. Circuit for monitoring light signals by means of a single monitor for a stop signal lamp and/or a proceed signal lamp, which monitor needs to be switched via contacts of two successively switching actuators in the forward and return lines of the signal lamp or lamps, in the stop signal circuit or proceed signal circuit, the monitor being subjected in each case upon the switching-off of a stop signal lamp or upon the switching-on of a proceed signal lamp in a single-pole fashion to a drop-out test via the contacts of the successively switching actuators, in which drop-out test the contacts of the respectively initially switching actuator reverse the flow direction for the monitor in preparation for switching on a proceed signal lamp, characterized in that at least the initially switchable actuator is designed as a control relay (SO) with non-mechanically coupled changeover contacts (SO/1, SO/2) , of which a first changeover contact (SO/1) is used to reverse the flow direction for the monitor (U) and of which a second changeover contact (SO/2), arranged between the first changeover contact (SO/1) and the monitor (U) in addition to the first changeover contact (SO/1) opens the relevant stop signal circuit upon the switching-of f of the stop signal lamp (LR) or upon switching-on the proceed signal lamp (LG) in a single-pole fashion, and switches the relevant proceed signal circuit through in a single-pole fashion by switching a connection to the monitor. 2. Circuit according to Claim 1, characterized—in- that the two actuators are designed as control relays (SO, S1) with non-mechanically coupled changeover contacts (SO/1, SO/2, Sl/1). 3. Circuit according to Claim 1 or 2, character-i-zed- in that each control relay (SO, S1) is designed mechan ically such that should a changeover contact be welded in one position it no longer changes upon changeover of the - 11 - relevant relay: the break contact remains closed and the make contact remains open. 4. Circuit according to Claim 1, 2 or 3, character ized—in that for the purpose of alternate and individual switching of proceed signal lamps and stop signal lamps (LG1, LR1, LG2, LR2, LR3) there is provided in a control and monitoring station an appropriate number of similarly-constructed signalling submodules (SM1 to SM4) to which either at least one proceed signal lamp and one stop signal lamp (LG1, LRl) or only at least one stop signal lamp or one proceed signal lamp (LG2, LR2, LR3) are connected towards the outdoor equipment via corresponding supply leads. 5. Circuit according to Claim 1, 2 or 3, character- zed—in- that the control relays (SO, S1) cooperating in pairs can be controlled by one or the other channel of a double computer system. 6. Circuit according to Claim 1, characterized in that the monitor (U) can be set to different operating points if required. 7 . Circuit according to Claim 6, characterized in that the monitor (U) is represented by a resistor (Rx), which can be set if required, in the supply circuit of the signal lamp (LR, LG) respectively to be monitored, the signalling voltage of which is fed to a window discriminator (FD) for evaluation. 8. Circuit according to Claim 7, charaterized in that the window discriminator (FD) is set up by cyclic connection of signalling voltages, detected in different signalling submodules (SM1 to SM4) , for monitoring the signal lamps (LRl, LG1, LG2, LR2, LG3) of a plurality of signalling submodules. 9. Circuit according to Claim 7 or 8, characterized i-n that the coupling-out of the signalling voltages to the discriminator, and the transmission of the respective evaluation result of the latter to an evaluation computer system is respectively performed via optocouplers (0K3, OKI) in a fail safe design. 10. Circuit according to one of Claims 1 to 9, - 12 - characterized in that the signal lamps are operated in a fashion free from earth, and in that at least one earth-fault detector is provided to monitor earth faults in the lamp circuits. Instead of signal relays, control relays (SO, S1) with non-mechanically coupled changeover contacts (SO/1, SO/2, Sl/1) are used to switch the signal lamps of a reliable light signal (LS). The control relays are designed mechanically such that should the individual changeover contacts be welded in one position they no longer change upon changeover of the relevant relay. The contacts are arranged in the supply leads to the signal lamps (LR, LG) such that mechanical fixing of one of the contacts is indicated by the next control operation at the latest during the stressing following the occurrence of this fault. This is brought about because the relevant signal lamp can no longer be switched on or that specific monitoring signals are lacking. The circuit according to the invention is intended, in particular, for controlling and monitoring light signals in rail transport.

Documents:

00235-cal-1997 abstract.pdf

00235-cal-1997 claims.pdf

00235-cal-1997 correspondence.pdf

00235-cal-1997 description(complete).pdf

00235-cal-1997 drawings.pdf

00235-cal-1997 form-1.pdf

00235-cal-1997 form-2.pdf

00235-cal-1997 form-3.pdf

00235-cal-1997 form-5.pdf

00235-cal-1997 gpa.pdf

00235-cal-1997 priority document.pdf

235-CAL-1997-CORRESPONDENCE 1.1.pdf

235-CAL-1997-FORM 27.pdf

235-CAL-1997-FORM-27.pdf

235-cal-1997-granted-abstract.pdf

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

235-cal-1997-granted-claims.pdf

235-cal-1997-granted-correspondence.pdf

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

235-cal-1997-granted-drawings.pdf

235-cal-1997-granted-examination report.pdf

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

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

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

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

235-cal-1997-granted-gpa.pdf

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

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

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

235-cal-1997-granted-specification.pdf

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