DE3813538A1 - Circuit arrangement for the monitored operation of two AC loads via a common supply line - Google Patents

Abstract

A circuit arrangement is specified which enables the supply and monitoring of two AC loads (rtH, rtN), of which the second comes into operation automatically in the event of the first failing, from an actuating mechanism via a common two-wire supply line. The two loads are supplied asymmetrically with respect to the polarity of the AC half-cycles. The actuating mechanism tests for the presence and the orientation of the asymmetry in the supply current. The asymmetry is achieved by means of devices in separate current paths for positive and negative AC half-cycles and by different attenuation or different transmission factors in these current paths. When the loads are switched over, the assignment of the AC half-cycle polarities to the current paths is also interchanged. <IMAGE>

Description

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

A circuit arrangement that provides feedback from Operating states of AC consumers over whose feed line permits, e.g. from the DE-OS 19 57 781 known. It is there from page 5, the last one Paragraph describes how the feedback from the Operating states of two signal lamps via the separate supply circuits of these. Signal lamps reach an assigned center. It rectified voltage is used for feedback, their polarity depending on which signal lamp thread in Operation is positive or negative.

In the known circuit arrangement, two completely separate supply circuits needed to enable the feedback. Furthermore become frame shorts or yourself accordingly  impacting wire contacts in the on the route located part of the circuit arrangement, in the signal box not recognized with certainty.

The invention has for its object in a Circuit arrangement of the type described above the number the cable cores required for supply and feedback to reduce and in addition to the feedback of the Operating states also the reporting of faults such as To allow socket shorts.

The object of the invention is achieved by the characterizing part of claim 1 specified Features solved.

The circuit arrangement according to the invention allows the Operating states of both consumers in terms of signals to report safely to the signal box. It is e.g. possible without additional signal lines from the signal box from determining whether a double-stranded Signal lamp of the main thread or, after breaking the Main thread, the secondary thread is in operation or whether a Total failure due to interruption of both threads or due to of a short circuit. Operation of the Main thread and the operation of the secondary thread call in Interlocking an asymmetrical supply alternating current certain, different phases. Disruptions, such as failure of both consumers or Version short, on the other hand, always lead to one symmetrical feed current, which, depending on its strength, associated with a short circuit or an interruption can be. With the circuit arrangement according to the Invention are therefore only per consumer pair two cable wires required for supply and monitoring.  

With more than two consumers, the Set up supply circuits with a common return line, so that for each additional consumer pair only one additional cable wire is required. A main signal with Double filament lamps for red, green and yellow light therefore only requires four wires for a safe, monitored operation. The signal lamps additionally monitored for socket short circuit.

The object of the invention is also achieved by the characterizing part of claim 2 specified Features solved. In contrast to the im Claim specified solution here is the Unbalance in the alternating current supply not with the help different windings of the lamp transformer but generated with the help of a special circuit, which are the AC half-waves of one polarity influenced. Such a circuit can, as in claim 5 and claim 6 described, from two in series lying, mutually connected Z diodes or a DIAC, or it can be one according to claim 7 Be leading edge circuit.

Claims 3 and 4 give exemplary embodiments for the part of the signal in use Circuit arrangement according to the invention, claims 8, 9 and 10 embodiments for one in the signal box detector circuit located on.

Based on 4 figures, embodiments of the Circuit arrangement according to the invention described will.  

Fig. 1 shows a solution in which a two-filament lamp is operated via a transformer tapped on the primary side.

FIG. 2 shows the solution corresponding to FIG. 1 with Z diodes on the primary side for influencing the amplitude of an AC half-wave

Fig. 3 is a two-filament lamps interface showing a tapped transformer on the secondary side

Fig. 4 shows current and voltage profiles in a signal box monitoring circuit.

In Fig. 1, a circuit arrangement for operating a dual-string signal lamp rtH, RTN is shown a lamp transformer T 1. Of this circuit arrangement, a part shown in the figure below a broken line is located in a so-called signal insert in the external system of a signal box, a part shown above is in the signal box itself and is used to monitor the operating state of the double-filament lamp.

During normal operation of the signal lamp, its main thread, which is located between connections 0 and 1, is switched on. It is fed from the secondary winding of the lamp transformer T 1 via primary windings of two further transformers T 2 and T 3 . The supply current for the lamp transformer is taken from an AC network N (switch contacts and fuse element are not shown). It flows through a monitoring transformer ÜT in the signal box and via a changeover circuit in the signal insert , which switches the individual AC half-waves according to their polarity and depending on the position of two changeover switches HÜ 2, NÜ 1 on separate paths of the full primary winding or a shortened primary winding formed by tapping of the lamp transformer T 1 supplies. The changeover switches are contacts of two relays, a main thread monitor HÜ and a secondary thread monitor NÜ. They are switched so that when the main thread monitor is energized (main thread in operation), the positive half-waves of the feed current flow through the shortened primary winding, but the negative half-waves of the feed current flow through the full primary winding of the lamp transformer, so that an asymmetrical feed current with larger positive current amplitudes and smaller negative current amplitudes can be observed. If the secondary thread (between connections 0 and 2 ) is in operation (secondary thread monitor NÜ excited, main thread monitor HÜ dropped), the changeover switches HÜ 2 and NÜ 1 are in a position opposite to that shown in FIG. 1. The positive half-waves of the supply current thus flow over the full, the negative half-waves over the shortened primary winding. An asymmetrical supply current with larger negative current amplitudes is observed in the signal box.

The observation and evaluation of the current amplitudes can be carried out by means of a circuit shown in FIG. 1, above, connected to a secondary winding of the monitoring transformer UT .

This consists of two diodes D 5 and D 6 , which rectify positive voltage half-waves induced by the supply current in oppositely polarized, symmetrical partial windings of the secondary winding of the monitoring transformer and thus charge capacitors C 1 and C 2 bridged by load resistors R 1 , R 2 . A comparator K compares the voltages present at the capacitors and controls a display device AZ, not shown.

For example, is the positive current half-wave of Feed currents are more developed than the negative ones Current half-wave, the more positive when passing Current half-wave capacitor to be charged a higher Have charging voltage. The output of the comparator is according to the voltage difference at its inputs assume high or low level. In order to avoid, that even the smallest voltage differences on the comparator can lead to asymmetry displays on the input side Threshold circuits are provided which cause that the comparator only for voltage differences responds to a predetermined minimum value exceed. It can also be used instead of a simple one Comparator provided a digital circuit be recorded numerically and depending on its value and polarity Controls display device.

The main thread monitor HÜ and secondary thread monitor NÜ have the task of monitoring the operating status of the individual signal lamp threads, ie to report their operating status and their failure. This is done, as already described above, using the changeover switches HÜ 2 and NÜ 1. However, it must be ensured that the main thread monitor is energized only when the main thread is in operation and working properly. The same applies to the secondary thread monitor. In the exemplary embodiment shown in FIG. 1, the two monitors are controlled via thyristors Th 1, Th 2 and are parallel to the lamp threads rtH, rtN . The control voltages for the thyristors are generated with the aid of the two transformers T 2 and T 3 , depending on the respective lamp filament operating current. The monitors can therefore only be excited when both voltage is present on the lamp thread to be monitored and current flows through the lamp thread. As a result, both a break in the lamp filament and a socket short circuit cause the respective monitor to fall off. If the lamp filament breaks, sufficient current does not flow through the transformer generating the thyristor control voltage, the thyristor therefore does not switch through. In the event of a short circuit in the socket (eg between connections 1 and 0 ), the operating voltage for the monitoring relay (eg HV ) is missing. Therefore, this is not excited.

In the circuit shown in FIG. 1, the operation of the secondary thread is additionally dependent on the state of the main thread, so that the secondary thread is automatically put into operation if the main thread breaks. This dependency is realized in a known manner by a contact HÜ 1 of the main thread monitor HÜ , which is in the feed line to the secondary thread and its monitor relay NÜ and keeps it switched off as long as the main thread monitor HÜ is energized.

If voltage is applied from the AC network N to the circuit arrangement shown in FIG. 1, both lamp threads initially go into operation for a short time, since the voltage induced in the secondary winding of the lamp transformer both at connection 1 and because the main thread monitor has not yet responded and therefore contact HÜ 1 is still closed, is present at connection 2 .

The current for the main thread flows through the primary windings of the transformers T 2 and T 3 , the current for the secondary thread only through the primary winding of the transformer T 2 . The voltages induced in the secondary windings of the two transmitters are in phase with the voltages applied to the switching paths of the two thyristors and control them during each half-wave polarized in the thyristor flow direction via their control electrodes protected by diodes D 3 and D 4 against negative voltages. If both lamp threads are in order, both monitors will respond. However, the secondary thread monitor NÜ falls off again after a short time because the contact HÜ 1 of the main thread monitor disconnects the secondary thread and thus also the secondary thread monitor from each voltage supply. The main thread monitor remains energized as long as voltage is applied to the main thread and operating current flows through the primary winding of the transformer T 3 .

The proper operation of the main yarn (tightened main filament monitor, fallen secondary filament monitor) is in the position shown in Fig. 1, the changeover switch HÜ 2 and NÜ 1 result and causes an asymmetry in the feed stream, which are characterized by higher amplitudes of the positive current half-waves and smaller amplitudes of the negative current half-waves and is determined in the signal box as described above. This causes the message "main thread intact and in operation" without using a special message line. If the main thread burns out, the current through the primary winding of the transformer T 3 breaks down except for a small remainder flowing over the winding of the main thread monitor. The voltage induced in the secondary winding of the transmission T 3 is no longer sufficient to drive a control current necessary to control the thyristor Th 1 via the control electrode of the thyristor Th 1 . The main thread monitor thus drops and its contact HÜ 1 switches on the secondary thread. Now, if the secondary thread is intact, the secondary thread monitor picks up because the thyristor Th 2, which receives a control current in phase with the operating voltage of the secondary thread from the secondary winding of the transformer T 2 , switches through. The status "secondary thread intact and in operation - main thread defective" is also reported to the signal box via the feed line. An asymmetrical feed current is again determined in the signal box, which, however, since the changeover switches HÜ 2 and NÜ 1 are now in the opposite position to the position shown in FIG. 1, has larger negative and smaller positive half-wave amplitudes. If the secondary thread also burns out, the thyristor Th 2 is also no longer activated, since no lamp current flows through the transformer T 2 . The secondary thread monitor drops out, its changeover contact NÜ 1 switches to the position shown. This means that both half-waves of the remaining feed current are conducted over the full primary winding of the lamp transformer. The feed current is therefore symmetrical and significantly weaker than when operating a lamp filament.

Both are noticed in the signal box and the total failure of the signal lamp can be displayed. However, in contrast to conventional wire-saving signal lamp circuits, the circuit shown in FIG. 1 is also able to report short circuits that occur, for example, to the lamp holder, to the signal box. If connections 1 and 0 or, in the case of secondary thread operation, 2 and 0 are connected to each other with low resistance, the voltage at the monitoring relay that is switched on breaks down, which causes its dropout. Such a short circuit is then also noticed in the event that a fuse provided for such short circuits in the signal box does not respond, for example during night operation and lower mains voltage. The drop in both monitoring relays (contact HÜ 2 in opposite position) causes positive and negative supply current half-waves to be conducted over the full primary winding, so that the supply current is symmetrical. In contrast to a failure due to an interruption of both lamp threads, however, a greatly increased supply current can be determined here as a result of the short circuit.

If a socket short circuit occurs between lamp connections 1 and 2 - this would have caused the operation of both lamp threads at the same time and, due to the current-limiting properties of the lamp transformer, would be associated with an impermissibly strong reduction in light radiation - both monitors are excited at the same time. Contact HÜ 1 is irrelevant because of the short circuit. In this case, the changeover switch NÜ 1 assumes a position opposite to the position shown in FIG. 1 and the feed current half-waves of both polarities are conducted via the shortened primary winding of the lamp transformer. A symmetrical feed current is determined in the signal box, which has approximately the same current intensity as would be found in the event of a socket short circuit between the lamp connections 1 and 0 or 2 and 0 .

The embodiment shown in Fig. 2 differs from that shown in Fig. 1 only in that the lamp transformer instead of a tapped primary winding, the various partial windings of which the differently polarized supply current half-waves can be supplied, contains a conventional primary winding, which supplies the supply current half-waves either directly or via two Z diodes Z 1 , Z 2 connected to each other can be supplied. A resistor can also be used instead of the two Zener diodes.

In FIG. 4, obtained with the tapped primary winding and with the Z-diode unbalanced current waveforms are illustrated schematically. FIG. 4a shows the curve I a prepared with tapped primary winding asymmetrical current waveform with larger positive current half-waves as a curve II a corresponding current waveform with larger negative current half-waves. FIG. 4b shows an asymmetrical current profile with larger positive current half-waves produced with Z-diodes connected to one another.

The voltages induced in the secondary winding of the monitoring transformer ÜT are proportional to the current profiles . After their rectification, different voltages VP +, VN +, VP -, VN - are set at the capacitors C 1 , C 2 in FIGS. 1 and 2, C 3, C 4 in FIG. 4, which are evaluated by the comparator K. and which are also shown in Fig. 4.

In an exemplary embodiment according to FIG. 3, instead of a tapped primary winding, a tapped secondary winding of the lamp transformer is provided for asymmetrizing the supply current. Instead of two thyristor-controlled main thread monitors, four AC relays are used, two of which (main thread monitor HÜ and secondary thread monitor NÜ ) are low-resistance and are located in the lamp thread circuits, the other two (main thread parallel relay HP and secondary thread parallel relay NP ) are designed with high resistance and the lamp thread is connected in parallel. This circuit also reports both thread breaks and socket short-circuits due to asymmetrical feed current. A thread break causes the respective monitoring relay in the lamp circuit to drop and thus the thread changeover and / or the signal to the signal box with the help of the switches HÜ 2 and NÜ 1. Socket shorts that bridge a lamp thread drop the respective parallel relay. This bridges the associated monitoring relay with a contact HP 2 or NP 2 and causes it to drop out. In the event of a short circuit between the connections 1 and 2 , the contacts NP 1 and NP 2, which change their position due to excitation of the secondary thread parallel relay NP , also excite the secondary thread monitor in addition to the main thread monitor. This causes symmetrical lamp current through the tapping of the secondary winding of the lamp transformer. Symmetrical feed current is therefore determined in the signal box. FIG. 3 shows in the part of the circuit on the interlocking side a monitoring circuit different from the monitoring circuit shown in FIG. 1 for evaluating the asymmetry of the feed current. In addition, a lamp monitoring circuit which is already present in conventional circuits and consists of a monitoring transformer ÜT 2 and a signaling relay M is provided here.

A contact M 1 of the signal relay switches on a signal lamp L 1 when the supply current falls below a minimum.

Claims (10)

1.Circuit arrangement for operating two AC consumers via a common feed line and at least one transformer from a signal box and for reporting back the operating states via the common feed line, characterized in that diodes ( D 1 , D 2 ; D 7 , D 8 ) are provided, via which the positive and negative current half-waves of the alternating current are separated from one another, differently designed windings of the transformer ( T 1 ) are supplied on the primary side or are removed on the secondary side such that the AC consumers ( rtH, rtN ) are connected to the transformer ( T 1 ) are switched on, that they can only be operated in certain mutually opposite phase positions of the alternating current and that there is a detector circuit ( DE ) in the signal box, which detects and evaluates the presence and polarity of an asymmetry in the alternating current and g If applicable, indicates which of the two consumers is in operation. 2.Circuit arrangement for operating two AC consumers via a common feed line and at least one transformer from an interlocking and for reporting the operating states via the common feed line, characterized in that antiparallel connected diodes ( D 1 , D 2 ) are provided for generating an asymmetry in the alternating feed current are, via the positive and negative current half-waves of the alternating current, separated from one another, fed to at least one winding of the transformer ( T 1 ) on the primary side or removed from the secondary side, with either the positive or the negative current half-waves being conducted via a circuit influencing their shape or their amplitude, that the alternating current consumers ( rtH, rtN ) are connected to the transformer ( T 1 ) in such a way that they can only be operated in certain mutually opposite phases of the alternating current and that a detector circuit ( DE ), which detects and evaluates the presence and polarity of an asymmetry in the alternating current and, if necessary, indicates which of the two consumers is in operation. 3. Circuit arrangement according to claim 1, characterized in that the transformer ( T 1 ) has a tapped primary winding, which is completely flowed through by feed alternating current half-waves of one polarity, partially by feed-alternating current half-waves of the other polarity via the tap, so that an asymmetrical one on the secondary winding AC voltage is present that the consumers ( rtH, rtN ) are assigned monitoring relays ( HÜ, NÜ ), each of which has a changeover contact ( HÜ 2, NÜ 1 ) one of the anti-parallel diodes ( D 1 , D 2 ), and that of the diode leading to the primary winding leads can switch from one of the winding connections used to feed the AC half-waves into the primary winding of the transformer to the other so that the monitoring relays ( HÜ, NÜ ) are switched so that they are energized as soon as the respectively assigned consumer ( rtH , rtN ) is in operation and that the changeover contacts ( HÜ 2, NÜ 1 ) are switched in such a way that current half-waves of different polarity are connected to different connections of the primary winding when one of the consumers is in operation and to the same connection in each case when no consumer is in operation or both consumers are in operation. 4. Circuit arrangement according to claim 1, characterized in that the transformer ( T 1 ) has a tapped secondary winding, the half waves of the one polarity of the consumers via the antiparallel diodes ( D 7 , D 8 ) alternating current, half waves of the other Polarity via the tapping, partially flowed through, that the consumers ( rtH, rtN ) are assigned monitoring relays ( HÜ, NÜ ), each of which has a changeover contact ( HU 2, NÜ 1 ) in one of the from the secondary winding to the anti-parallel diodes ( D 7 , D 8 ) leading supply lines is arranged so that it can switch the relevant supply line from one of the winding connections used to remove the AC half-waves from the secondary winding to the other, so that the monitoring relays ( HÜ, NÜ ) are switched so that they are excited , as soon as the respectively assigned consumer ( rtH, rtN ) is in operation and that the changeover contacts ( HÜ 2 , NÜ 1 ) are switched in this way are that current half-waves of different polarity flow over different connections of the secondary winding when one of the consumers is in operation and via the same connection when no consumer is in operation or both consumers are in operation. 5. Circuit arrangement according to claim 2, characterized characterized in that the amplitude of the positive or negative half-wave influencing circuit two Z-diodes in opposite polarity is formed. 6. Circuit arrangement according to claim 2, characterized in that a circuit influencing the amplitude of the positive or negative half-waves is formed by a DIAC . 7. Circuit arrangement according to claim 2, characterized characterized that a the form of positive or circuit influencing negative half-waves Gating circuit is. 8. Circuit arrangement according to one of the preceding claims, that the interlocking detector circuit ( DE ) contains at least one transformer ( ÜT ), the primary winding of which is alternating current flow, that the voltages induced by the positive and negative current half-waves in a secondary winding of the transformer are separated from one another , smoothed by means of capacitors ( C 1 , C 2 ; C 3 , C 4 ) and fed to the inputs of a comparator ( K ) and that the output of the comparator is dependent on the occurrence of a difference between the smoothed voltages and the direction of the voltage gradient Display device ( AZ ) controls. 9. A circuit arrangement according to claim 8, characterized in that the voltages induced on the secondary side are supplied to the smoothing capacitors ( C 3 , C 4 ) connected to one another and to a connection of the secondary winding via diodes ( D 9 , D 10 ) which are polarized in opposite directions so that the the diodes-connected connections of the capacitors are connected to one another via a load resistor ( R 3 ) and that the comparator ( K ) is connected to a first input with a center tap of the load resistor and with a second input to the connections of the smoothing capacitors connected to the secondary winding. 10. Circuit arrangement according to claim 9, characterized in that in the connection between the center tap of the load resistor ( R 3 ) and the comparator input to form a voltage threshold, a parallel connection of oppositely polarized diodes or a series connection of oppositely polarized Z diodes is provided.