Circuit assembly for the state monitoring and logging of overvoltage protection devices or overvoltage protection systems

Abstract

The invention relates to a circuit assembly for the state monitoring and logging of overvoltage protection devices or overvoltage protection systems by means of pulse current monitoring, comprising at least one passive RFID transponder having an inductively coupled voltage supply, wherein in the case of an event of the overvoltage protection device or the overvoltage protection system, the RFID transponder antenna circuit is influenced, in particular interrupted, short circuited, or detuned, so that disturbance processes can be identified. According to the invention, a coil L2 is provided on a discharge line of the overvoltage protection device or the overvoltage protection system that carries pulse currents that occur, which coil L2 is oriented in such a way that the field caused by pulse current passes through the coil winding surface, wherein the coil L2 is connected to at least one switching device, which is connected on the antenna circuit of the RFID transponder to the inductor L1 there in order to influence the antenna circuit at least at times.

Claims

1. Circuit arrangement for the status check and logging of overvoltage protection devices or overvoltage protection systems by means of monitoring pulsed currents, comprising at least one RFID transponder having an inductively coupled voltage supply, wherein, in the event case of the overvoltage protection device or the overvoltage protection system, the RFID transponder antenna circuit is influenced, in particular interrupted, short-circuited or detuned so that interfering events are identifiable, wherein a down conductor of the overvoltage protection device or the overvoltage protection system, which carries occurring pulsed currents, is provided with a coil which is oriented such that the field induced by the pulsed currents penetrates the winding surface of the coil, wherein the coil (L2) is in communication with at least one switching device which is connected to the antenna circuit of the RFID transponder with the inductor (L1) provided there so as to periodically influence the antenna circuit.

2. Circuit arrangement according to claim 1, wherein the coil (L1) forming the inductor has an orientation which ensures that there is no induction or only little induction when pulsed currents occur.

3. Circuit arrangement according to claim 1, wherein the coil (L2) is connected to a Graetz rectifier bridge (G1) which is connected, on the output side, by a diode (D1) to the switching element or switching device (S1), wherein the switching element (S1) keeps the antenna circuit of the RFID transponder, comprising the coil (L1) and a capacitor (C1), closed in the initial state.

4. Circuit arrangement according to claim 3, wherein if the switching element (S1) is triggered, a half-wave of the voltage generated by the coil (L1) is blocked by the rectifier bridge (G1) and the diode (D1), so that the sensitivity of the RFID communication is influenced, in particular reduced.

5. Circuit arrangement according to claim 1, wherein the coil (L2) is configured as a toroidal core coil or as an air-cored coil, in particular a Rogowski coil.

6. Circuit arrangement according to claim 3, wherein several diodes (D1.1 to D1.x) are provided on the output side of the Graetz rectifier bridge (G1), each of which lead via a resistor (R2.1 to R2.x) to an associated switching element (S1.1 to S1.x), wherein minimum triggering levels for the associated switching elements (S1.1 to S1.x) can be predefined based on the values of the resistors (R2.1 to R2.x) so as to accomplish an evaluation of occurring pulsed currents or impulse currents and, to this end, each of the switching elements (S1.1 to S1.x) is in communication with an own RFID transponder (IC1.1 to IC1.x) and the respective antenna circuit thereof.

7. Circuit arrangement according to claim 1, wherein the switching elements or switching devices are configured as fuses.

8. Circuit arrangement according to claim 1, wherein the switching elements are configured as transistors (T), in particular MOSFETs, wherein a time constant can be set by means of an RC element arranged in the control branch of the respective transistor (T) in order to close the interrupted antenna circuit again or cancel the influence acting on the antenna circuit.

9. Circuit arrangement according to claim 1, wherein if the switching device is triggered it is possible to build up a communication connection by an increased coupling between a transponder reading device and the antenna circuit so as to read out information stored in the transponder.

10. Circuit arrangement according to claim 9, wherein the coupling can be enhanced by an increased transmitting power.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS(S)

(1) FIG. 1 shows a schematic circuit diagram of a first embodiment of the solution according to the invention for the status check and logging of overvoltage protection devices, having a fuse as switching element or switching device;

(2) FIG. 2 shows a schematic circuit arrangement of the solution according to the invention, in which energy generated by coil L2 is divided to several switching devices, in particular fuses, for the easier evaluation of the impulse current having occurred in the conductor;

(3) FIG. 3 shows a schematic circuit arrangement including an electronic switch as the switching device, by means of which the RFID antenna circuit can be interrupted for a certain time so as to realize a counting device for the occurrence of pulses, and

(4) FIG. 4 an exemplary arrangement of the inventive pulsed current coil and the RFID antenna circuit coil on an air-termination device for the monitoring of same.

DETAILED DESCRIPTION OF THE INVENTION

(5) As illustrated in FIGS. 1, 2 and 3, the pulsed current i flowing through a down conductor generates an induction voltage in a coil L2 arranged on or near the down conductor.

(6) Via a Graetz rectifier bridge G1 and a diode D1 connected in the forward direction, this induction voltage is applied to a switching device configured as fuse S1.

(7) If the energy applied to coil L2 is higher than the melting integral of the fuse S1, the fuse is triggered.

(8) The fuse S1 is unloaded in the initial state. Thus, the antenna circuit, formed by the RFID coil L1 and the RFID capacitor C1, the latter establishing the RFID transmission with the transponder IC1, is closed.

(9) If S1 is triggered, a half-wave of the voltage generated by the RFID coil L1 is blocked by the rectifier bridge G1 and the diode D1.

(10) As a consequence, the sensitivity of the transmission channel to a (non-illustrated) reading station is reduced. If the coupling between the reading device and the transponder circuit is reduced, the transmission is switched off when the fuse S1 opens.

(11) By an enhanced coupling, e.g. increase of the transmitting power of the reading device, a communication to the transponder, respectively, reading device can be reestablished although the fuse S1 is interrupted. The advantage of this is that the information stored in the transponder can still be read out even though the monitoring of the pulsed current is activated.

(12) In one embodiment a toroidal core may be used for the coil L2 so as to increase the sensitivity for the pulsed current detection. The toroidal core may also be hinged or configured with a mobile leg, as is known in connection with so-called current probes. Equally suited is an air-cored coil, in particular a Rogowski coil, to realize the inductor L2 as user-friendly as possible.

(13) An exemplary dimensioning for monitoring the discharge current in overvoltage protection devices is based on an RFID coil L1 with L=7.4 mH and N=480 windings.

(14) The coil L2 has, for instance, an inductance L=1.1 pH with N=12 windings on the toroidal core.

(15) A Schurter MAG FF, 200 mA is used as a fuse.

(16) The above-described dimensioning results in a triggering of the fuse at a pulsed current 8/20 s at a level of approximately 4.3 kA.

(17) According to the invention, the minimum triggering level can be varied over a broad range by selecting specific fuse types with regard to release current and characteristic. Another essential parameter is the number of windings, the surface of the winding, the core material for coil L2 and the specification of the resistor value R1 connected on the output side of the Graetz bridge G1.

(18) The separated arrangement of the antenna circuit coil L1 and the pulsed current coil L2 according to FIG. 1 allows, in the different embodiments, the coupling of the discharge path for the pulsed current to the evaluation unit according to the invention.

(19) In order not to be committed to a threshold of the impulse current i flowing in the conductor there is proposed, according to FIG. 2, a distribution of the energy generated by coil L2 to several switching elements, respectively, fuses S1.1 to S1.x so as to allow an easy evaluation of the impulse current occurring in the conductor.

(20) According to the illustration in FIG. 2 a node is formed on the output side of the Graetz rectifier bridge, downstream of the resistor R1, on which, in the example shown, three diodes D1.1, D1.2 and D1.x are provided. A resistor R2.1, R2.2 and R2.x is respectively connected in series to diodes D1.1, D1.2 and D1.x. Each resistor then leads to the fuse S1.1, S1.2 and S1.x provided in each branch. An independent RFID circuit IC1.1, IC1.2 and IC1.x is formed for each of the aforementioned fuses. Each RFID circuit includes an RFID coil L1.1, L1.2 and L1.x with a corresponding antenna circuit capacitor C1.1, C1.2 and C1.x.

(21) A parallel connection of fuses as switching devices with different release currents alone does not allow the setting of thresholds. The reason for this is the inverse proportionality between the release current and the resistance of a fuse. In order to realize the necessary threshold switches all fuses S1.x are then configured with the same release current, the distribution of the release current being realized by resistors R2.1, R2.2 and 2.x. The lower the resistor value R2.x, the higher is the partial current flowing in this branch, so that the associated fuse is then triggered at the lowest threshold.

(22) The response of the individual RFID circuits can be realized by the so-called AOR (Answer On Request) function which is offered by transponders available on the market. Alternatively, a different dimensioning of the carrier frequency for the different RFID circuits is conceivable.

(23) The above-explained embodiments according to FIGS. 1 and 2 allow the nonrecurring registration of the exceedance of one or more threshold stages. A counting of events is impossible, however.

(24) If one replaces the fuse by an electronic switch, configured as a self-conducting MOSFET T1, as is shown in FIG. 3, the antenna circuit of the transponder IC1 can be interrupted for a certain period. After a time which can be set by the time constant R2, C2 the antenna circuit is closed again.

(25) If a continuous interrogation of the transponder IC1 is carried out by a reading device it is possible to realize a counting device for the occurrence of pulses, provided that the reading and evaluation unit works with an interrogation interval smaller than the time constant of the electronic switch T1. C2 and R2 are arranged as parallel circuits at the control input of the electronic switch T1.

(26) The schematic circuit according to FIG. 3 allows a registration of the discharge current in an air-termination device of a lightning protection system. To this end, the pulse monitoring by an RFID transponder is accommodated in a housing which can be fixed to an air-termination device or a corresponding down conductor.

(27) The orientation of the coil L2 is chosen such that magnetic field H (also see FIG. 4), caused by the impulse current i, penetrates the winding surface of the coil.

(28) The winding surface of the RFID antenna circuit coil L1 is arranged such that preferably no induction is caused by the magnetic field H of the pulsed current.

(29) A schematic arrangement of coils L1 and L2 of this type is illustrated in FIG. 4.

(30) Here, the winding surface planes of coils L1 and L2 are substantially perpendicular to one another.

(31) The magnetic field H penetrates the plane of the coil surface of coil L2 quasi perpendicularly, so that the induction is at a maximum.

(32) The present passive RFID transponder is read out by means of an inductively coupled voltage y through L1 and a non-illustrated reading device.

(33) This measure does not require electrical connections. Hence, the circuit for the pulse monitoring can be accommodated in a housing, hermetically sealed and weather-protected, which is a particular advantage for the arrangement on air-termination devices.

(34) The evaluation and reading unit is accommodated separately, in a separate housing. Depending on the selected transmission method and the characteristics of the coil L1 it is possible to bridge defined distances. If RFID transponders having an AOR function are used the interrogation of several air-termination devices can be accomplished by a single evaluation unit.

SEQUENCE LISTING

(35) Not Applicable