CN220711100U - Low-voltage relay protection device for communication external wiring loop against strong current interference - Google Patents
Low-voltage relay protection device for communication external wiring loop against strong current interference Download PDFInfo
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- CN220711100U CN220711100U CN202321459902.2U CN202321459902U CN220711100U CN 220711100 U CN220711100 U CN 220711100U CN 202321459902 U CN202321459902 U CN 202321459902U CN 220711100 U CN220711100 U CN 220711100U
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- 238000004891 communication Methods 0.000 title claims abstract description 38
- 230000001052 transient effect Effects 0.000 claims abstract description 101
- 230000000903 blocking effect Effects 0.000 claims abstract description 34
- 230000001629 suppression Effects 0.000 claims abstract description 31
- 238000002955 isolation Methods 0.000 claims abstract description 25
- 239000003990 capacitor Substances 0.000 claims description 6
- 230000002093 peripheral effect Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- MLLUMKXNINTJAC-UHFFFAOYSA-N 1,3-dioxoisoindole-4-sulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC2=C1C(=O)NC2=O MLLUMKXNINTJAC-UHFFFAOYSA-N 0.000 description 1
- 208000025274 Lightning injury Diseases 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
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Abstract
The utility model discloses a low-voltage relay protection device for resisting strong current interference of a communication external wiring loop, which comprises a CPU module, a first protection unit, a second protection unit, a first unit output terminal and a second unit output terminal, wherein the first unit output terminal and the second unit output terminal are connected with a field communication bus of external controlled equipment; the first protection unit comprises a photoelectric isolation circuit I, a differential level converter, a transient current blocking unit TBU I and a transient voltage suppression unit TVSI. The utility model cuts off the external strong current interference from the internal weak current system, prevents overvoltage or overcurrent from being connected into each weak current functional module in the low-voltage protection device in series, reduces economic loss and ensures safe operation of the device.
Description
Technical Field
The utility model relates to the technical field of communication protection devices, in particular to a low-voltage relay protection device for resisting strong electric interference of a communication external wiring loop.
Background
The low-voltage 380V relay protection device (hereinafter referred to as a protection device) generally has the functions of field bus communication and analog 4-20mA output, and the field bus communication and the analog 4-20mA output send information to a remote electric monitoring system and a remote process control system through long wiring. The protection device belongs to electric secondary equipment, is often not arranged in an independent electric secondary cell in a switch cabinet like a high-voltage relay protection device, but is generally arranged in a drawer cabinet space, and is positioned in a closed and compact environment space together with various electric primary equipment such as a circuit breaker, a contactor, a fuse switch and the like; various secondary devices inside the drawer also usually directly take one phase from three-phase voltage of the alternating current system as a control power supply, and an independent control power supply which is completely electrically isolated from the alternating current system is not provided; the field bus communication cable of the protection device and the 4-20mA output signal line cable are connected with a plurality of links through the device wiring terminal, the drawer internal wiring, the drawer secondary plug and the drawer external wiring, and are sent to the far end through the long-distance signal line. When the alternating current system suffers lightning stroke, short circuit fault, switching operation and other transient overvoltage possibly generated at moment, in view of the complicated and unfavorable electrical environment factors, various links of the transient alternating current overvoltage transmitted from the communication and 4-20mA are connected into the relay protection device, the communication and 4-20mA belong to weak current functional parts in the device, and under the working condition, the device is easy to be irreversibly damaged for a short time or a long time.
In practical application, because the external wiring of field bus communication is often star-shaped and connected in series, overvoltage affects a plurality of protection devices through one same communication bus, and the problem of 'one bad and one bad' occurs sometimes, so that economic loss is brought to enterprises, great hidden danger is brought to safe and stable operation of power plants and enterprises, and it is important to improve the strong electric interference resistance of the communication channels of the low-voltage protection devices.
Therefore, a low-voltage relay protection device for resisting strong electric interference of a communication external wiring loop is needed to be designed so as to solve the problems.
Disclosure of Invention
The utility model aims to provide a low-voltage relay protection device which reduces the overall damage of a corresponding weak current functional circuit and the device, reduces economic loss and ensures the strong current interference resistance of a communication external wiring circuit for safe operation of the device.
In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:
the low-voltage relay protection device comprises a CPU module, a first protection unit, a second protection unit, a first unit output terminal and a second unit output terminal, wherein the first unit output terminal and the second unit output terminal are connected with a field communication bus of an external controlled device; the first protection unit comprises a photoelectric isolation circuit I, a differential level converter, a transient current blocking unit TBU I and a transient voltage suppression unit TVS I, one end of the photoelectric isolation circuit I is connected with the UART module, and the other end of the photoelectric isolation circuit I is connected with the transient current blocking unit TBU I in series through the differential level converter; one end of the transient voltage suppression unit TVSI is connected in parallel between the differential level converter and the transient current blocking unit TBU I, and the other end of the transient voltage suppression unit TVSI is connected with signal ground.
Preferably, the transient current blocking unit TBU i is two in parallel connection.
Preferably, the second protection unit includes a photoelectric isolation circuit ii, a DAC converter, a transient current blocking unit TBU ii, and a transient voltage suppression unit TVS ii, one end of the photoelectric isolation circuit ii is connected to the SPI module, the other end of the photoelectric isolation circuit ii is connected in series with one end of the transient current blocking unit TBU ii through the DAC converter, the other end of the transient voltage suppression unit TVS ii is connected in parallel between the DAC converter and the transient current blocking unit TBU ii, and the other end of the transient voltage suppression unit TVS ii is connected to a signal ground.
Preferably, the first unit output terminal includes a connection terminal a 'and a connection terminal B' disposed in parallel.
Preferably, the TVS unit TVS i includes a TVS1, a TVS2, a TVS3, and a TVS4, where an anode of the TVS1 is connected to the connection terminal a', a cathode of the TVS1 is connected to a cathode of the TVS2, and an anode of the TVS2 is connected to a signal ground; the anode of the transient diode TVS3 is connected with the connecting terminal B', the cathode of the transient diode TVS3 is connected with the cathode of the transient diode TVS4, and the anode of the transient diode TVS4 is connected with signal ground.
Preferably, the TVS ii includes a TVS5 and a TVS6, an anode of the TVS5 is connected between the DAC converter and the TBU ii, a cathode of the TVS is connected to an anode of the TVS6, and an anode of the TVS6 is connected to the signal ground.
Preferably, the resistor further comprises resistors R1 and R2 and a capacitor C1, one end of the resistor R1 is connected with a wiring terminal A ', one end of the resistor R2 is connected with a wiring terminal B', and the other ends of the resistor R2 and the resistor R3 are grounded through the capacitor C1.
Due to the adoption of the technical scheme, the utility model has the following beneficial effects:
(1) The low-voltage relay protection device for resisting strong current interference of the communication external wiring loop disclosed by the utility model is matched with the transient current blocking unit TBU through the transient voltage suppression unit TVS of the first protection unit and the transient voltage suppression unit TVS of the second protection unit, so that the external strong current interference is blocked from an internal weak current system, and overvoltage or overcurrent is prevented from being connected into each weak current functional module in the low-voltage protection device in series, so that short-term or long-term irreversible damage is caused, and the stable operation of the device is influenced.
(2) The R1 and the R2 are matched resistors, impedance between a signal source and a transmission line is matched, reflection is reduced, oscillation is avoided, meanwhile, an RC filter is formed by the RC filter, the distributed capacitance of the signal line and the input capacitance C1 of a later-stage circuit, the steepness of the signal edge can be effectively weakened, and overshoot is prevented.
(3) The low-voltage relay protection device for resisting strong current interference of the communication external wiring circuit can effectively reduce the integral damage of the corresponding weak current functional circuit and the device, reduce economic loss and ensure the safe operation of the device.
Drawings
Fig. 1 is a block diagram of the structure of embodiment 1 of the present utility model.
Fig. 2 is a block diagram of the structure of embodiment 2 of the present utility model.
In the drawings, a 1-CPU module, a 2-UART module, a 3-SPI module, a 4-photoelectric isolation circuit I, a 5-photoelectric isolation circuit II, a 6-differential level converter, a 7-DAC converter, an 8-transient voltage suppression unit TVAI, a 9-transient voltage suppression unit TVAI, a 10-transient current blocking unit TBU I, an 11-transient current blocking unit TBU II, a 12-connection terminal A ', a 13-connection terminal B', and a 14-Iout signal line
Detailed Description
In order to make the objects, technical solutions and advantages of the present utility model more apparent, the present utility model will be further described in detail below by referring to the accompanying drawings and by illustrating preferred embodiments. It should be noted, however, that many of the details set forth in the description are merely provided to provide a thorough understanding of one or more aspects of the utility model, and that these aspects of the utility model may be practiced without these specific details.
Example 1
As shown in fig. 1, the low-voltage relay protection device for resisting strong current interference of a communication external wiring loop comprises a CPU module, a first protection unit, a second protection unit, a first unit output terminal and a second unit output terminal, wherein the first unit output terminal and the second unit output terminal are connected with a field communication bus of an external controlled device; the first protection unit comprises a photoelectric isolation circuit I, a differential level converter, a transient current blocking unit TBU I and a transient voltage suppression unit TVS I, wherein one end of the photoelectric isolation circuit I is connected with the UART module, and the other end of the photoelectric isolation circuit I is sequentially connected with the differential point level converter and the transient current blocking unit TBU I in series; the transient voltage suppression unit TVSI is connected in parallel between the differential level converter and the transient current blocking unit TBU I, and the other end of the transient voltage suppression unit TVSI is connected with signal ground.
The transient current blocking units TBU I are two in parallel connection. The second protection unit comprises a photoelectric isolation circuit II, a DAC converter, a transient current blocking unit TBU II and a transient voltage suppression unit TVS II, one end of the photoelectric isolation circuit II is connected with the SPI module, the other end of the photoelectric isolation circuit II is sequentially connected with the DAC converter and the transient current blocking unit TBU II in series, the transient voltage suppression unit TVS II is connected between the DAC converter and the transient current blocking unit TBU II in parallel, and the other end of the transient voltage suppression unit TVS II is connected with signal ground.
The first unit output terminal comprises a wiring terminal A 'and a wiring terminal B' which are arranged in parallel; the communication data to be transmitted in the CPU module is directly converted into an RS232 serial port signal, then the RS232 serial port signal is converted into a pair of differential level signals A and B through a photoelectric isolation circuit and a differential level converter, the rear end of each signal wire is connected in parallel with a pair of transient voltage suppression units TVSI, and then is connected in series with a transient current blocking unit TBU I, and then is connected to an external system field communication bus through connection terminals A 'and B' of a low-voltage protection device.
The transient voltage suppression unit TVS I comprises a transient diode TVS1, a transient diode TVS2, a transient diode TVS3 and a transient diode TVS4, wherein the anode of the TVS1 is connected with the wiring terminal A', the cathode of the TVS1 is connected with the cathode of the TVS2, and the anode of the transient diode TVS2 is connected with signal ground; the anode of the transient diode TVS3 is connected with the connecting terminal B', the cathode of the transient diode TVS3 is connected with the cathode of the transient diode TVS4, and the anode of the transient diode TVS4 is connected with signal ground.
The transient voltage suppression unit TVS II comprises a transient diode TVS5 and a transient diode TVS6, wherein the anode of the transient diode TVS5 is connected between the DAC converter and the transient current blocking unit TBU II, the cathode of the transient diode is connected with the anode of the transient diode TVS6, and the anode of the transient diode TVS6 is connected with signal ground.
The data quantity of 4-20mA which is required to be output in the CPU module is transmitted to the DAC converter through the photoelectric isolation module by the SPI bus, and the DAC converter converts the 4-20mA into a current signal from a digital signal and outputs the current signal through an Iout signal line of the DAC converter.
The external communication of the low-voltage relay protection device mainly comprises two functions of field bus communication and 4-20mA output. The CPU module is the core of the device and is connected with other modules, and the CPU module adopts TMS320F28334. The embedded processor is a 32-bit high-performance embedded processor, has 256KFlash,34K SARAM,12 bit A/D on a main frequency 150M chip, and has rich peripheral equipment: UART module, SPI module, 88 programmable multiplexing GPIO pins etc. satisfies relay protection device's function and performance requirement comprehensively.
Devices in the fieldbus and 4-20mA functional loop that are resistant to external strong current disturbances are a transient voltage suppression unit TVS and a transient current blocking unit TBU. The TBU adopts R3777 which is a single-channel bidirectional high-speed overcurrent protection element, the transient overcurrent starting threshold is 300mA, the blocking action time is 0.8us, the TBU can work under the maximum 425V alternating current voltage, and the current flowing through a line during blocking is less than 10mA; the TVS employs CDSOT23-SM712 with an asymmetric breakdown voltage of +13.3v and-7.5V that matches the common mode range of the transceiver of +12v to-7V in conventional communication differential level conversion to provide optimal protection.
Example 2
The utility model is identical to the other circuits and structural connections of embodiment 1, except that: the resistor is characterized by further comprising resistors R1 and R2 and a capacitor C1, wherein one end of the resistor R1 is connected with a wiring terminal A ', one end of the resistor R2 is connected with a wiring terminal B', and the other ends of the resistor R2 and the resistor R3 are grounded through the capacitor C1.
The UART module of the low-voltage protection device is connected with the CPU module through a peripheral bus, communication data to be transmitted in the CPU module is directly converted into RS232 serial port signals, the RS232 serial port signals are converted into a pair of differential level signals A and B through a photoelectric isolation circuit and a differential level, the rear end of each signal wire is connected with a pair of transient voltage suppression units TVS in parallel, a transient current blocking unit TBU is connected in series, and the signal wires are connected to an external system field communication bus through connection terminals A 'and B' of the low-voltage protection device. Normally, the TVS has a very high impedance to ground and the TBU has a low impedance, so both have little effect on normal circuit operation. When a transient alternating current voltage greater than the breakdown voltage of the TVS exists in an external system at the rear end of the terminal, the TVS clamps the voltage within a voltage limit value within 1 nanosecond; meanwhile, when the TVS breaks down, the current flowing through the signal line is instantaneously increased to the current limiting threshold value of the TBU, the TBU unit has high impedance to block transient energy, the channel where the TBU unit is located can be disconnected within 1us, and in the rest time of the transient, the TBU is kept in a blocking state, and only the current smaller than 1mA flows through the signal line. The cooperation of the units cuts off the external strong current interference from an internal weak current system, prevents overvoltage or overcurrent from being connected into each weak current functional module in the low-voltage protection device in series, and causes short-term or long-term irreversible damage to influence the stable operation of the device. When the over-current amplitude is reduced below the threshold voltage, the TBU unit can automatically return to a low-resistance state, the line connection is restored, the communication module of the low-voltage protection device is restored to be connected with an external system, and the communication function is restored to operate.
The SPI module of the low-voltage protection device is connected with the CPU module through a peripheral bus, 4-20mA data quantity required to be output in the CPU module is transmitted to the DAC converter through the photoelectric isolation module by the SPI bus, and the DAC converter converts 4-20mA into a current signal from a digital signal and outputs the current signal through an Iout signal line of the DAC converter. Similarly, a pair of transient voltage suppression units TVS are connected in parallel to the rear end of the Iout signal line, and a transient current blocking unit TBU is connected in series, and then connected to an external system through a terminal Iout' of the low voltage protection device. When the external system has transient overvoltage or overcurrent, the TVS instantly clamps the overvoltage and the TBU blocks the overcurrent to be protected by the combination, so that the external transient strong current alternating current interference is isolated from a weak current functional loop in the device, and the device is prevented from being damaged; when the transient strong current is disturbed, the TBU unit can automatically recover the low-resistance state, the DAC module of the low-voltage protection device is recovered to be connected with an external system, and the 4-20mA function is recovered to be output.
The foregoing is merely a preferred embodiment of the present utility model and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present utility model, which are intended to be comprehended within the scope of the present utility model.
Claims (7)
1. A low-voltage relay protection device for resisting strong electric interference of a communication external wiring loop is characterized in that: the low-voltage relay protection device comprises a CPU module, a first protection unit, a second protection unit, a first unit output terminal and a second unit output terminal, wherein the first unit output terminal and the second unit output terminal are connected with a field communication bus of external controlled equipment; the first protection unit comprises a photoelectric isolation circuit I, a differential level converter, a transient current blocking unit TBU I and a transient voltage suppression unit TVS I, one end of the photoelectric isolation circuit I is connected with the UART module, and the other end of the photoelectric isolation circuit I is connected with the transient current blocking unit TBU I in series through the differential level converter; one end of the transient voltage suppression unit TVSI is connected in parallel between the differential level converter and the transient current blocking unit TBU I, and the other end of the transient voltage suppression unit TVSI is connected with signal ground.
2. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 1, wherein the low-voltage relay protection device is characterized in that: the transient current blocking units TBU I are two in parallel connection.
3. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 2, wherein the low-voltage relay protection device is characterized in that: the second protection unit comprises a photoelectric isolation circuit II, a DAC (digital-to-analog converter), a transient current blocking unit TBU II and a transient voltage suppression unit TVS II, one end of the photoelectric isolation circuit II is connected with the SPI module, the other end of the photoelectric isolation circuit II is connected with one end of the transient current blocking unit TBU II in series through the DAC, the other end of the transient voltage suppression unit TVS II is connected between the DAC and the transient current blocking unit TBU II in parallel, and the other end of the transient voltage suppression unit TVS II is connected with signal ground.
4. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 1, wherein the low-voltage relay protection device is characterized in that: the first unit output terminal includes a connection terminal a 'and a connection terminal B' arranged in parallel.
5. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 4, wherein the low-voltage relay protection device is characterized in that: the transient voltage suppression unit TVS I comprises a transient diode TVS1, a transient diode TVS2, a transient diode TVS3 and a transient diode TVS4, wherein the anode of the TVS1 is connected with the wiring terminal A', the cathode of the TVS1 is connected with the cathode of the TVS2, and the anode of the transient diode TVS2 is connected with signal ground; the anode of the transient diode TVS3 is connected with the connecting terminal B', the cathode of the transient diode TVS3 is connected with the cathode of the transient diode TVS4, and the anode of the transient diode TVS4 is connected with signal ground.
6. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 3, wherein: the transient voltage suppression unit TVS II comprises a transient diode TVS5 and a transient diode TVS6, wherein the anode of the transient diode TVS5 is connected between the DAC converter and the transient current blocking unit TBU II, the cathode of the transient diode is connected with the anode of the transient diode TVS6, and the anode of the transient diode TVS6 is connected with signal ground.
7. The low-voltage relay protection device for resisting strong electric interference of a communication external wiring circuit according to claim 5, wherein the low-voltage relay protection device is characterized in that: the resistor is characterized by further comprising resistors R1 and R2 and a capacitor C1, wherein one end of the resistor R1 is connected with a wiring terminal A ', one end of the resistor R2 is connected with a wiring terminal B', and the other ends of the resistor R2 and the resistor R3 are grounded through the capacitor C1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321459902.2U CN220711100U (en) | 2023-06-08 | 2023-06-08 | Low-voltage relay protection device for communication external wiring loop against strong current interference |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321459902.2U CN220711100U (en) | 2023-06-08 | 2023-06-08 | Low-voltage relay protection device for communication external wiring loop against strong current interference |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220711100U true CN220711100U (en) | 2024-04-02 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321459902.2U Active CN220711100U (en) | 2023-06-08 | 2023-06-08 | Low-voltage relay protection device for communication external wiring loop against strong current interference |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220711100U (en) |
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2023
- 2023-06-08 CN CN202321459902.2U patent/CN220711100U/en active Active
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