Vibrating wire sensor acquisition terminal multichannel lightning protection circuit

Abstract

The utility model relates to the technical field of data acquisition equipment. The multi-channel lightning protection circuit comprises a plurality of first-stage TVS protection circuits, a current limiting device, a second-stage MOV protection circuit, a third-stage GDT protection circuit, a grounding circuit and a channel selection circuit, the second-stage MOV protection circuit, the third-stage GDT protection circuit and the current limiting device are connected in parallel and then are connected in series with the first-stage TVS protection circuit; a vibrating wire signal anti-surge protection circuit composed of a first-stage TVS protection circuit, a current limiting device, a second-stage MOV protection circuit and a third-stage GDT protection circuit bears surge pulses induced on a vibrating wire sensor signal line, prevents the surge pulses from entering the channel selection circuit, and discharges surge pulse energy through a grounding circuit. According to the utility model, the problems of slow surge pulse energy release, large equipment size and the like of the existing vibrating wire sensor acquisition terminal can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of data acquisition equipment, in particular to a multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal. Background Art

[0002] In the current dam safety monitoring data acquisition system, the sinusoidal quantity data acquisition terminal is responsible for connecting to the vibrating string sensor and vibrating the string piece in the sensor through a specific method, so that the coil in the sensor emits a sinusoidal quantity, and then collects the frequency of the sensor's sinusoidal quantity. At present, most vibrating string sensors are installed outdoors and connected to the vibrating string acquisition terminal through wires. They are easily affected and damaged by lightning, which can cause damage to the vibrating string acquisition terminal and equipment failure.

[0003] Although most of the current multi-channel vibrating string acquisition terminals have built-in lightning protection devices or use external lightning arresters, and have certain lightning protection and surge resistance capabilities, the multi-channel vibrating string acquisition terminal products in the industry generally have the following problems in product design:

[0004] 1. The surge pulse energy is discharged slowly, with only one-level TVS (transient voltage suppression diode) protection or two-level TVS plus GDT (ceramic gas discharge tube) protection. For example: the existing Chinese patent CN210111604U discloses a lightning protection circuit for the signal interface of a vibrating string collector. This solution is designed as a two-level surge protection circuit from the perspective of the electrical characteristics of the vibrating string signal and the requirements of the post-stage protection circuit. It can match the surge protection requirements of the vibrating string signal and the vibrating string collection system. In the actual surge level test, it also fully meets the surge protection requirements of LPZ0B-3. However, the surge pulse energy is discharged slowly.

[0005] 2. The equipment with multi-channel acquisition is large in size and high in production cost. Because the sinusoidal quantity generated by the vibrating string sensor is relatively weak, an operational amplifier is needed to amplify the signal, and each acquisition channel needs to be equipped with a data conversion channel, which greatly increases the production cost and size of the equipment. Utility Model Content

[0006] The utility model aims to solve at least one of the technical problems raised in the above-mentioned background technology, and provides a multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal with strong lightning protection capability and multi-channel protection, which can solve the problems of slow surge pulse energy discharge and large equipment size in the existing vibrating string sensor acquisition terminal.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is:

[0008] A multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal, the interface of which has multiple acquisition channels, including multiple first-level TVS protection circuits, current limiting devices, second-level MOV protection circuits, third-level GDT protection circuits, grounding circuits and channel selection circuits; multiple first-level TVS protection circuits are respectively connected to multiple acquisition channels; the second-level MOV protection circuit, third-level GDT protection circuit and current limiting device are connected in parallel and then connected in series with the first-level TVS protection circuit; a vibrating string signal anti-surge protection circuit composed of the first-level TVS protection circuit, the current limiting device, the second-level MOV protection circuit and the third-level GDT protection circuit withstands surge pulses induced on the vibrating string sensor signal line, prevents surge pulses from entering the channel selection circuit, and discharges surge pulse energy through the grounding circuit.

[0009] As a further improvement of the utility model, the first-level TVS protection circuit adopts a TVS transient voltage suppression diode of model SMAJ13CA.

[0010] As a further improvement of the utility model, the second-level MOV protection circuit adopts a varistor with a model of 05D390K.

[0011] As a further improvement of the utility model, the third-level GDT protection circuit is a ceramic gas discharge tube.

[0012] As a further improvement of the utility model, the channel selection circuit adopts a relay of model HFD4 / 5.

[0013] As a further improvement of the present invention, the signal lines of the vibrating-string sensor are respectively connected to a plurality of the first-level TVS protection circuits.

[0014] Due to the adoption of the above technical solution, the utility model has the following beneficial effects:

[0015] The utility model adopts a three-level lightning protection and surge resistance design for a multi-channel lightning protection circuit of a vibrating string sensor acquisition terminal, which can solve the problem that the equipment is easily damaged and the surge pulse energy is slowly discharged when the vibrating string acquisition terminal is installed outdoors and struck by lightning, thereby ensuring the safety of the equipment and facilities and greatly reducing the risk of safety accidents. By sharing the second and third level lightning protection circuits through multiple acquisition channels, the production cost and volume of the equipment are greatly reduced while ensuring the function.

[0016] The connection between the signal line of the vibrating string sensor and the acquisition terminal of the utility model is in a disconnected state when the vibrating string sensor is not working, thereby ensuring the safety of the acquisition terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a circuit block diagram of a multi-channel lightning protection circuit for a vibrating-string sensor acquisition terminal proposed by the utility model;

[0018] Figure 2 This is a circuit schematic diagram of a multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal proposed by the utility model. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] In the description of the present utility model, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present utility model; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0021] See also Figure 1-Figure 2A multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal, the interface of which has multiple acquisition channels, is characterized in that: it includes multiple first-level TVS protection circuits, current limiting devices, second-level MOV protection circuits, third-level GDT protection circuits, grounding circuits and channel selection circuits; multiple first-level TVS protection circuits are respectively connected to multiple acquisition channels; the second-level MOV protection circuit, the third-level GDT protection circuit and the current limiting device are connected in parallel and then connected in series with the first-level TVS protection circuit; that is, the second-level MOV protection circuit, the third-level GDT protection circuit and the current limiting device are arranged in parallel, and then connected to the rear stage of the multiple first-level TVS protection circuits, and connected to the grounding circuit; the vibrating string signal anti-surge protection circuit composed of the first-level TVS protection circuit, the current limiting device, the second-level MOV protection circuit and the third-level GDT protection circuit withstands the surge pulse induced on the vibrating string sensor signal line, prevents the surge pulse from entering the channel selection circuit, and discharges the surge pulse energy through the grounding circuit. The utility model increases multi-stage lightning protection devices at the signal interface and enables multiple channels to share a group of lightning protection devices, thereby achieving good lightning protection effect while reducing the volume of the equipment and lowering the production cost.

[0022] In the utility model, the three-level lightning protection circuit is composed of a third-level GDT protection circuit, a second-level MOV protection circuit, and a first-level TVS protection circuit which is connected in parallel and then in series with a current limiting device, wherein the first-level TVS protection circuit includes at least two TVSs, the channel selection circuit is connected with 2 or 4 signal lines, and each signal line is connected in parallel with the TVS; the second-level MOV protection circuit includes an MOV, the third-level GDT protection circuit includes a GDT, the current limiting device is a current limiting resistor, the MOV, GDT, and current limiting resistor are arranged in parallel, one end of which is connected to the TVS of multiple channel selection circuits, and the other end is connected to the grounding circuit.

[0023] The signal lines of the multi-channel vibrating string sensor are respectively connected to multiple first-level TVS protection circuits. Due to the conduction response speed of the first-level TVS protection circuit> the second-level MOV protection circuit> the third-level GDT protection circuit, when the surge pulse energy passes through the lightning protection and surge protection circuit, the voltage first reaches the clamping voltage of the first-level TVS protection circuit, and the first-level TVS protection circuit is turned on first. However, due to the existence of the current limiting device, the voltage across the current limiting device will gradually increase. When it reaches the clamping voltage of the second-level MOV protection circuit, the second-level MOV protection circuit is then turned on and begins to discharge the surge pulse energy. If the energy cannot be discharged in a very short time, the voltage across the current limiting device continues to increase until it reaches the breakdown voltage of the third-level GDT protection circuit. At this time, the third-level GDT protection circuit is turned on to discharge a large amount of surge pulse energy.

[0024] In the embodiment of the utility model, the first-level TVS protection circuit includes at least two TVS transient voltage suppression diodes of model SMAJ13CA. On the basis of lightning protection, a transient voltage suppression diode (TVS) is added to absorb the surge power that may be generated, ensure the voltage stability between the two poles, and avoid damage to the precision devices in the electronic circuit. The signal lines of the vibrating string sensor are respectively connected to multiple first-level TVS protection circuits. In this embodiment, each signal line of the vibrating string sensor is connected in parallel to the first-level TVS protection circuit, and then connected in series to the second and third-level protection circuits. Because the clamping voltage of the first-level TVS protection circuit is greater than the signal voltage of the vibrating string sensor, it will not have any effect on the channel selection circuit during normal use. When the signal line of the vibrating string sensor is entangled with the induced surge pulse, the voltage between the signal line and the ground is higher than the clamping voltage of the first-level TVS protection circuit, and the first-level TVS protection circuit is turned on, and the surge pulse energy is diverted to the second and third-level protection circuits, thereby protecting the safety of the channel selection circuit.

[0025] Current limiting devices usually use large-value resistors. The main function of the current limiting device is to raise the voltage across the current limiting device, so that the voltage across the parallel second-stage MOV protection circuit and the third-stage GDT protection circuit is higher than the clamping voltage of the second-stage MOV protection circuit and the breakdown voltage of the third-stage GDT protection circuit, thereby making the second-stage and third-stage protection circuits conductive and discharging energy.

[0026] The second-stage MOV protection circuit uses a varistor model 05D390K. When the voltage across the second-stage MOV protection circuit is higher than the clamping voltage of the second-stage MOV protection circuit, the response time of the second-stage MOV protection circuit is tens of nanoseconds, and the second-stage MOV protection circuit changes from a high-resistance state to a conducting state, thereby allowing the surge pulse energy to flow into the grounding circuit.

[0027] The third-level GDT protection circuit is a ceramic gas discharge tube. The GDT device has the characteristics of large discharge current, small inter-electrode capacitance, and high insulation resistance, which can effectively realize lightning protection. When the voltage across the third-level GDT protection circuit is higher than the breakdown voltage of the third-level GDT protection circuit, the response time of the third-level GDT protection circuit is several hundred nanoseconds, and the third-level GDT protection circuit changes from a high-resistance state to a conducting state, thereby allowing the surge pulse energy to flow into the grounding circuit. The response speed of the third-level GDT protection circuit is slower than that of the second-level MOV protection circuit, but the discharge speed is higher than that of the second-level MOV protection circuit. Therefore, GDT acts as the third-level protection and cooperates with the second-level MOV protection circuit to discharge the surge pulse energy.

[0028] The grounding circuit can divert surge pulse energy to the ground, protecting the safety of equipment and lines.

[0029] The channel selection circuit uses a relay of model HFD4 / 5. The relay is used to control the connection between the vibrating string sensor signal line and the acquisition terminal. When the vibrating string sensor is not needed to work, the signal line is disconnected from the acquisition terminal. Even if there is surge pulse energy coming from the signal line, the safety of the acquisition terminal can be guaranteed. The acquisition terminal actively controls the connection between the sensor signal line and the acquisition terminal. When the value of the channel needs to be collected, the control relay connects the signal line and the acquisition terminal. After the collection is completed, the control relay disconnects the sensor signal line from the acquisition terminal.

[0030] The above description is a detailed description of the preferred feasible embodiment of the utility model, but the embodiment is not used to limit the scope of the patent application of the utility model. All equivalent changes or modified changes completed under the technical spirit suggested by the utility model should fall within the patent scope covered by the utility model.

Claims

1. A multi-channel lightning protection circuit for a vibrating string sensor acquisition terminal, wherein the interface of the vibrating string sensor acquisition terminal has multiple acquisition channels, characterized in that: It includes multiple first-level TVS protection circuits, current limiting devices, second-level MOV protection circuits, third-level GDT protection circuits, grounding circuits and channel selection circuits; multiple first-level TVS protection circuits are respectively connected to multiple acquisition channels; the second-level MOV protection circuit, the third-level GDT protection circuit and the current limiting device are connected in parallel and then in series with the first-level TVS protection circuit; the vibrating string signal anti-surge protection circuit composed of the first-level TVS protection circuit, the current limiting device, the second-level MOV protection circuit and the third-level GDT protection circuit withstands the surge pulse induced on the vibrating string sensor signal line, prevents the surge pulse from entering the channel selection circuit, and discharges the surge pulse energy through the grounding circuit.

2. A multi-channel lightning protection circuit for a vibrating-wire sensor acquisition terminal according to claim 1, characterized in that: The first-level TVS protection circuit uses a TVS transient voltage suppression diode model SMAJ13CA.

3. A multi-channel lightning protection circuit for a vibrating-wire sensor acquisition terminal according to claim 1, characterized in that: The second-level MOV protection circuit uses a varistor model 05D390K.

4. A multi-channel lightning protection circuit for a vibrating-wire sensor acquisition terminal according to claim 1, characterized in that: The third level GDT protection circuit is a ceramic gas discharge tube.

5. The multi-channel lightning protection circuit of a vibrating-wire sensor acquisition terminal according to claim 1 is characterized in that: The channel selection circuit uses a relay model HFD4 / 5.

6. A multi-channel lightning protection circuit for a vibrating-wire sensor acquisition terminal according to claim 1, characterized in that: The signal lines of the vibrating-string sensor are respectively connected to a plurality of the first-level TVS protection circuits.

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