Abstract
A circuit arrangement for revealing light signal errors, in particular for railway safety systems, includes an electronic signal generator, which can be disconnected in a reversible manner in the event of an error, and a control part, configured for incandescent lamps, for controlling and monitoring the signal generator. The device for revealing errors includes an error differentiator between the line-related interference voltage and error of the signal generator. The reliability of the error differentiation is improved and rendered independent of capacitive intermediate energy storage devices, in that the signal generator is connected to a resistance arrangement such that the signal generator voltage is greater, in high-resistance signal generators, than an interference voltage.
Claims
1. A circuit arrangement for revealing errors in a signaling light, the circuit arrangement comprising: an electronic signal transmitter configured to disconnect itself reversibly in the event of an error; and an actuating part, configured for incandescent lamps, for actuating and monitoring said signal transmitter; a resistor configuration connected to said signal transmitter to enable a revelation of errors to differentiate between line-conditioned influencing voltage and errors in the signal transmitter in that a high-impedance signal transmitter prompts a signal transmitter voltage to be higher than the line-conditioned influencing voltage; and wherein a voltage threshold value is provided for error differentiation between the signal transmitter voltage and the influencing voltage, and wherein a rise above the voltage threshold value indicates an error in the signal transmitter and a drop below the voltage threshold value indicates a presence of an influencing voltage.
2. The circuit arrangement according to claim 1, wherein the signaling light is a light signal for a railway safety installation.
3. The circuit arrangement as claimed in claim 1, wherein said resistor configuration is a disconnectable resistor configuration.
4. The circuit arrangement as claimed in claim 3, wherein said resistor configuration is disconnected when errors are revealed.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) The invention is explained in more detail below with reference to illustrations in the figures, in which:
(2) FIG. 1 shows the basic principle of a signal circuit,
(3) FIG. 2 shows a simplified illustration of the basic principle shown in FIG. 1,
(4) FIG. 3 shows a signal circuit with an erroneous signal transmitter in the manner of illustration shown in FIG. 2,
(5) FIG. 4 shows a graph for the switch-on behavior of an error-free signal transmitter,
(6) FIG. 5 shows a graph for the switch-on behavior with an erroneous signal transmitter, and
(7) FIG. 6 shows a graph of the switch-on behavior in the event of influencing.
DESCRIPTION OF THE INVENTION
(8) FIG. 1 illustrates the connection of a signal transmitter 1 via a signal line 2, which is connected via a switch S1 to a signal voltage U1 that is provided by an actuating part, which is usually a long way away from the signal transmitter 1, but that has a voltage source 3. In this case, U2 is the signal transmitter voltage and U3 is a line-conditioned influencing voltage. The signal transmitter 1 has the signal transmitter voltage U2 and the impedance Z3 associated with it. The signal voltage U1 is connected to the signal transmitter 1 by the actuating part via S1 and the signal line 2 with the impedance Z1. The influencing voltage U3 is permanently applied to the signal transmitter 1 via Z2.
(9) An appropriately simplified circuit illustration is shown in FIG. 2. The impedance Z1 of the signal voltage U1 is much lower than the impedance Z2 of the influencing voltage U3. Hence,
(10)
for the signal transmitter voltage and
(11)
for the influencing voltage.
(12) U2 for the signal transmitter voltage is much higher than U2 for the influencing voltage.
(13) FIG. 3 additionally shows a signal transmitter error as Z3.1. This supplementary impedance Z3.1 of the signal transmitter 1 means that U2 for the signal transmitter voltage falls to the value of U2 for the influencing voltage. Hence,
(14)
(15) Consequently, when measuring the voltage U2 across the signal transmitter 1 that is not switched to high impedance, it is not possible to distinguish between influencing voltage and signal transmitter voltage.
(16) In order to produce distinguishability, the signal transmitter 1 has, according to the invention, a connected resistor arrangement that reduces the influencing voltage.
(17) The graphs in FIGS. 4 to 6 each show 33 successfully measured current/voltage value pairs. Current and voltage are not normalized. The measured value 637 in the three graphs denotes a voltage threshold value 4 for distinguishing between influencing voltage and signal transmitter voltage in the high-impedance state of the signal transmitter.
(18) In FIG. 4, the signal transmitter 1 operates in error-free fashion at low voltage, as a result of which, in stable continuous operation, the signal transmitter 1 has a voltage drop across it that results from Z1 and Z3. Since the signal transmitter 1 is not at high impedance, there is a larger voltage drop across Z1 than in the high-impedance state of Z3. For this reason, the measured voltage is lower than the threshold value 4. Signal transmitter voltage and influencing voltage are distinguished only when the signal transmitter is at high impedance.
(19) FIGS. 5 and 6 show different error states, wherein the current/voltage value pairs with voltage value 0 indicate a collapsed signal transmitter voltage, which means that the current values of these value pairs are also invalid.
(20) FIG. 5 shows a typical measured value characteristic for a low-impedance error Z3.1 in the signal transmitter 1 and a connected signal voltage U1. It can be seen that the voltage of the value pairs 1, 7, 8, 13, 14, 19 and 20 is very low, whereas the current is very high. The high current values in connection with the high voltage values of the value pairs 6, 12 and 18 exceed the threshold value 4, since the signal transmitter 1 has switched to the high-impedance state for these value pairs 6, 12 and 18. The high-impedance state for the cited value pairs 6, 12 and 18 and for the rise above the threshold value 4 restarts the signal transmitter 1. Following repeated false starts for the value pairs 1, 7 and 19, the signal transmitter 1 switches to high impedance for the value pairs greater than 22 and thus reports its error to the actuating part. In this case, the signal transmitter voltage is higher than the threshold value 4.
(21) FIG. 6 shows the switch-on behavior at influencing voltage (U3). In the case of influencing, the signal transmitter 1 first of all starts and then switches to the high-impedance state. From the fifth value pair onwards, the signal transmitter 1 is at high impedance and the voltage remains below the threshold value 4, as a result of which the influencing voltage is identified. The switch S1 of the actuating part is open in this state.
(22) When the switch S1 of the actuating part closes, the voltage rises above the threshold value 4 and the signal transmitter 1 starts as in FIG. 4.
