APL surge protection device

Abstract

The invention discloses an APL surge protection device, which comprises a surge protection circuit and a leakage current alarm circuit, and is characterized in that the surge protection circuit comprises a coupling assembly and a transient suppression diode which are connected in parallel between an APL signal input end and an APL signal output end; the leakage current alarm circuit comprises an alarm indication circuit and an alarm output circuit, and the alarm indication circuit is connected in parallel with the two ends of the transient suppression diode and is used for detecting the leakage current of the transient suppression diode and sending out a photoelectric alarm; and the alarm output circuit is connected with the current output end of the transient suppression diode, and when the leakage current of the transient suppression diode reaches the effect of driving the contact of the alarm output circuit to be closed, the alarm output circuit outputs an alarm signal to the outside. According to the invention, a transient suppression diode is designed to protect various APL devices on an APL bus from being harassed by lightning, and a set of life cycle detection and alarm indication circuit is designed for a failure mode of the transient suppression diode, so that a user can timely find potential abnormal risks and quickly take measures at the initial stage of failure.

Description

Technical Field

[0001] The invention belongs to the technical field of lightning protection, and in particular relates to an APL surge protector. Background Art

[0002] APL (Advanced Physical Layer)-two-wire (single-pair) Ethernet physical layer designed for process industry, based on IEEE 802.3cg 10BASE-T1L (IEEE802.3cg-2019) standard, 10Mbps communication speed, maximum communication distance 1000 meters, two-wire communication cable can simultaneously power field equipment, explosion-proof design specifications are applicable to the star topology of trunk (Trunk) plus spur (Spur) in hazardous areas, standard IEC61158-2 cable, terminal wiring, user-friendly installation and maintenance.

[0003] In the application of APL bus network architecture, the longest communication distance from the power switch to the field switch trunk is 1000 meters, and the longest communication distance from the field switch to the field APL instrument branch (Spur) is 200 meters. Such long field wiring is very susceptible to lightning strikes during actual operation, which may affect the normal communication of signals at the least, or even damage the APL switch or field instruments and other equipment. Therefore, a lightning protection solution based on APL equipment is needed. Summary of the invention

[0004] The purpose of the present invention is to provide an APL surge protector to protect various APL devices on the APL bus from lightning strikes, and to design a set of circuits for life cycle detection and alarm indication of transient suppression diodes according to the failure mode of the transient suppression diodes, so that users can promptly discover potential abnormal risks in the early stage of failure and take quick measures.

[0005] To solve the above problems, the technical solution of the present invention is:

[0006] An APL surge protector comprises: a surge protection circuit and a leakage current alarm circuit;

[0007] The surge protection circuit includes a coupling component and a transient suppression diode connected in parallel between the APL signal input terminal and the signal output terminal;

[0008] The leakage current alarm circuit includes an alarm indication circuit and an alarm output circuit. The alarm indication circuit is connected in parallel to both ends of the transient suppression diode and is used to detect the leakage current of the transient suppression diode and issue a photoelectric alarm.

[0009] The alarm output circuit is connected to the current output end of the transient suppression diode, and when the leakage current of the transient suppression diode reaches the level driving the contact of the alarm output circuit to close, the alarm output circuit outputs an alarm signal to the outside;

[0010] Wherein, the alarm indication circuit includes a diode bridge, a resistor and a photodiode, the first end of the diode bridge is connected to the current output end of the transient suppression diode, the second end of the diode bridge is connected to the APL signal output end, the third end of the diode bridge is connected to the resistor, and the fourth end of the diode bridge is connected to the current input end of the transient suppression diode; the resistor is connected in series with the photodiode and then connected to the current input end of the transient suppression diode.

[0011] According to an embodiment of the present invention, two ends of the transient suppression diode are connected to a diode assembly, and the diode assembly is used to achieve normal output of the APL signal without distinguishing between positive and negative poles.

[0012] According to an embodiment of the present invention, the diode assembly includes a first diode group, a second diode group, a third diode group, and a fourth diode group, wherein the first diode group connects a first end of an APL signal input and a current input end of the transient suppression diode, the second diode group connects a second end of an APL signal input and a current input end of the transient suppression diode, the third diode group connects a current output end of the transient suppression diode and a first end of an APL signal output, and the fourth diode group connects a current output end of the transient suppression diode and a second end of an APL signal output; wherein the first end and the second end of the APL signal input are positive and negative ends of the APL signal input, and the first end and the second end of the APL signal output are two ends corresponding to the first end and the second end of the APL signal input, respectively.

[0013] According to an embodiment of the present invention, the coupling component includes a gas discharge tube and a varistor connected in parallel, the first inductor and the third inductor are connected in series at both ends of the gas discharge tube and the varistor respectively, and the second inductor and the fourth inductor are connected in series at both ends of the varistor and the transient suppression diode respectively.

[0014] According to one embodiment of the present invention, when a forward lightning current is input, the discharge current path flowing through the transient suppression diode is: APL signal input first end → first inductor → second inductor → first diode group → transient suppression diode → alarm output circuit → fourth diode group → fourth inductor → third inductor → APL signal input second end.

[0015] According to one embodiment of the present invention, when a negative lightning current is input, the discharge current path flowing through the transient suppression diode is: APL signal input second end → third inductor → fourth inductor → second diode group → transient suppression diode → alarm output circuit → third diode group → second inductor → first inductor → APL signal input first end.

[0016] According to one embodiment of the present invention, if the transient suppression diode is damaged, leakage current will be generated when the APL signal flows in, and the flow path of the APL signal is: APL signal input first end → first inductor → second inductor → second end and third end bridge arm of the diode bridge → resistor → light emitting diode → transient suppression diode → alarm output circuit → first end and fourth end bridge arm of the diode bridge → fourth inductor → third inductor → APL signal input second end.

[0017] According to one embodiment of the present invention, if the transient suppression diode is damaged, leakage current will be generated when the APL signal flows in, and the flow path of the APL signal is: the second end of the APL signal input → the third inductor → the fourth inductor → the fourth end and the third end bridge arm of the diode bridge → the resistor → the light emitting diode → the transient suppression diode → the alarm output circuit → the first end and the second end bridge arm of the diode bridge → the second inductor → the first inductor → the first end of the APL signal input.

[0018] According to an embodiment of the present invention, the protection voltage of the transient voltage suppressor diode is greater than 50V.

[0019] According to an embodiment of the present invention, the APL surge protector is installed on a trunk line from a power switch to a field switch, and / or installed on a branch line from a field switch to a field APL instrument.

[0020] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0021] The APL surge protector in one embodiment of the present invention includes: a surge protection circuit and a leakage current alarm circuit, wherein the surge protection circuit includes a coupling component and a transient suppression diode connected in parallel between the APL signal input terminal and the signal output terminal; the leakage current alarm circuit includes an alarm indication circuit and an alarm output circuit, the alarm indication circuit is connected in parallel to the two ends of the transient suppression diode, and is used to detect the leakage current of the transient suppression diode and issue a photoelectric alarm; the alarm output circuit is connected to the current output end of the transient suppression diode, and when the leakage current of the transient suppression diode reaches the contact closure of the driving alarm output circuit, the alarm output circuit outputs an alarm signal to the outside. In order to protect various APL devices on the APL bus from lightning harassment, and in view of the failure mode of the transient suppression diode, a set of circuits for its life cycle detection and alarm indication are designed, so that users can timely discover potential abnormal risks in the early stage of its failure and take measures quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an application scenario diagram of an APL surge protector in one embodiment of the present invention;

[0023] Figure 2 is a basic principle diagram of a surge protector in one embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of an APL surge protector in one embodiment of the present invention;

[0025] Figure 4 It is a structural schematic diagram of a signal adaptive APL surge protector in one embodiment of the present invention;

[0026] Figure 5 A schematic diagram of a current path when lightning strikes in one embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of a forward APL signal path when a transient suppression diode is damaged in one embodiment of the present invention;

[0028] Figure 7 FIG. 4 is a schematic diagram of a negative APL signal path when a transient suppression diode is damaged in one embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following is a further detailed description of an APL surge protector proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0030] Please see Figure 1In the application of APL bus network architecture, APL surge protectors can be added to the trunk (Trunk) from the power switch to the field switch and the branch (Spur) from the field switch to the field APL instrument to achieve the effect of lightning protection for APL bus related equipment.

[0031] In the APL bus, the maximum power of the Trunk network connecting the power switch and the field switch is 57.5W / 50V, and the maximum power of the Spur network connecting the field switch and the field APL instrument is 1.11W / 12V. Therefore, the protection voltage of the selected transient suppression diode must be greater than the maximum voltage of 50V and have a certain margin so as not to affect normal signal transmission. Figure 2 The basic working principle of APL surge protector: When the surge voltage is applied to the input of the protection circuit, the fastest responding transient suppression diode (TVS1) will act first. By selecting appropriate coupling element (inductor or resistor) parameters, the circuit design can be designed before the transient suppression diode may be damaged. As the discharge current increases, the voltage drop on L2 and L4 plus the voltage drop on TVS1 reaches the breakdown voltage of the varistor (RVS1), and then RVS1 starts to discharge. Similarly, as the discharge current further increases, the voltage drop on L1 and L3 plus the breakdown voltage of MOV1 reaches the action voltage of the gas discharge tube (GDT1), and finally GDT1 releases a larger surge current. When transmitting normal APL signals, these protection devices are equivalent to open circuits and will not perform any actions.

[0032] The surge protector and its internal lightning protection devices have a lifespan, which is related to the number of discharges and the size of the lightning energy. The gas discharge tube (GDT1) and the varistor (RVS1) have slow response and high withstand voltage, and are generally not easy to fail; relatively speaking, the transient suppression diode (TVS1) with the fastest response time and the lowest withstand voltage is the most likely to fail. The failure of the transient suppression diode (TVS1) is a slow gradual process. This embodiment provides an APL surge protector while utilizing the characteristics of the internal transient suppression diode (TVS1) that is most prone to failure. After being damaged and degraded, it begins to leak current until it completely short-circuit fails. A leakage current detection circuit is designed to provide an alarm indication to the user and an alarm output to the system.

[0033] Please see Figure 3The APL surge protector includes: a surge protection circuit and a leakage current alarm circuit. The surge protection circuit includes a coupling component and a transient suppression diode TVS1 connected in parallel between the APL signal input terminal and the signal output terminal. The leakage current alarm circuit includes an alarm indication circuit and an alarm output circuit. The alarm indication circuit is connected in parallel to both ends of the transient suppression diode TVS1 to detect the leakage current of the transient suppression diode TVS1 and issue a photoelectric alarm. The alarm output circuit is connected to the current output end of the transient suppression diode TVS1. When the leakage current of the transient suppression diode TVS1 reaches the contact closure of the driving alarm output circuit, the alarm output circuit outputs an alarm signal to the outside.

[0034] from Figure 3 It can be seen that the alarm output circuit is a relay SW1, the coil of the relay is connected to the current output end of the transient suppression diode TVS1 and the APL signal output end. When an alarm signal is generated, ALM1 and ALM2 of the relay output an alarm signal to the external system.

[0035] The alarm indication circuit includes a diode bridge U1, a resistor R1 and a photodiode LED1, wherein the first end of the diode bridge U1 is connected to the current output end of the transient suppression diode TVS1, the second end of U1 is connected to the APL signal output end, the third end of U1 is connected to the resistor R1, and the fourth end of U1 is connected to the current input end of the transient suppression diode TVS1. The resistor R1 is connected in series with the photodiode LED1 and then connected to the current input end of the transient suppression diode TVS1.

[0036] The coupling component includes a gas discharge tube GDT1 and a varistor RVS1 connected in parallel. The two ends of the gas discharge tube and the varistor are respectively connected in series with a first inductor L1 and a third inductor L3. The two ends of the varistor and the transient suppression diode are respectively connected in series with a second inductor L2 and a fourth inductor L4.

[0037] Through the above-mentioned APL surge protector, various APL devices on the APL bus can be protected from lightning disturbances; and based on the alarm indication and alarm output when the transient suppression diode in the APL surge protector is damaged, full life cycle detection can be achieved.

[0038] In order to facilitate the installation of the APL surge protector and to achieve the goal of not distinguishing between positive and negative poles in both lightning current signal and APL signal transmission, this embodiment provides the following signal adaptive APL surge protector. Figure 4 , the APL surge protector is Figure 3 On this basis, a gating diode component is connected at both ends of the transient suppression diode TVS1, and the gating diode component is used to achieve the normal output of the APL signal without distinguishing between the positive and negative poles.

[0039] Specifically, the gate diode assembly includes a first diode group D1, a second diode group D2, a third diode group D3, and a fourth diode group D4, wherein the first diode group D1 connects the first end (IN1) of the APL signal input and the current input end of the transient suppression diode, the second diode group D2 connects the second end (IN2) of the APL signal input and the current input end of the transient suppression diode, the third diode group D3 connects the current output end of the transient suppression diode and the first end (OUT1) of the APL signal output, and the fourth diode group D4 connects the current output end of the transient suppression diode and the second end (OUT2) of the APL signal output. The first end and the second end of the APL signal input are the positive and negative ends of the APL signal input, and the first end and the second end of the APL signal output are the ends corresponding to the first end and the second end of the APL signal input, respectively.

[0040] Please see Figure 5 The working principle of the above signal adaptive APL surge protector during lightning current discharge is as follows: When a positive (IN1+, IN2-) lightning current strikes, the discharge current path through the transient suppression diode TVS1 is as shown by the solid arrow: port IN1→inductor L1, L2→diode group D1→transient suppression diode TVS1 and relay SW1 coil→diode group D4→inductor L4, L3→port IN2. When a negative (IN1-, IN2+) lightning current strikes, the discharge current path through the transient suppression diode (TVS1) is as shown by the dotted arrow: port IN2→inductor L3, L4→diode group D2→transient suppression diode TVS1 and relay SW1 coil→diode group D3→inductor L2, L1→port IN1. Since the lightning current is a μs-level fast pulse, it will not drive the ms-level relay SW1 coil to cause the contact to operate, nor will it trigger the alarm indication circuit (U1, R1, LED1) to work.

[0041] Please see Figure 6, when a normal signal with a positive direction (IN1+, IN2-) is input to the input end, such as a 4-20mA APL signal, if the transient suppression diode TVS1 is not damaged, it will be completely open circuit. At this time, the signal is positive with OUT1 and negative with OUT2, and the output is normal. The surge protector will not produce any action and will not have any impact on the normal signal. If the transient suppression diode TVS1 is damaged, leakage current will be generated when the normal signal passes through. The normal signal flows through the following route: port IN1→inductor L1, L2→lower right arm of bridge U1→R1 and LED1→APL transient suppression diode TVS1 and relay SW1 wire package→upper left arm of bridge U1→inductor L4, L3→port IN2, thus forming a current loop. At this time, the conduction voltage drop required for the selection diode group (D1~D4) is too high and it will not conduct. Instead, the leakage current passes through the alarm indicator light to light it up. Its brightness is determined by the size of the leakage current. When the leakage current reaches the level that can drive the relay SW1 contact to close, ALM1 and ALM2 output an alarm signal to the subsequent system.

[0042] Please see Figure 7 , when a negative (IN1-, IN2+) normal signal, such as 4-20mA, is input to the input terminal, if the transient suppression diode TVS1 is not damaged, it will be completely open circuit. At this time, the signal is negative with OUT1 and positive with OUT2, and the output is normal. The surge protector will not produce any action, nor will it have any impact on the normal signal. If the transient suppression diode TVS1 is damaged, leakage current will be generated when the normal signal passes through. The leakage current flows through the following route: port IN2 → inductor L3, L4 → the lower left arm of the bridge U1 → R1 and LED1 → transient suppression diode TVS1 and relay SW1 wire package → the upper right arm of the bridge U1 → inductor L1, L2 → port IN1, thus forming a current loop. At this time, the conduction voltage drop required for the selection diode group (D1~D4) is too high and it will not conduct. Instead, the leakage current passes through the alarm indicator light to light it up. Its brightness is determined by the size of the leakage current. When the leakage current reaches the level that can drive the relay SW1 contact to close, ALM1 and ALM2 output an alarm signal to the subsequent system.

[0043] In this way, alarm indication and alarm output based on damage of transient suppression diode in the APL surge protector are realized, and full life cycle detection is realized. In addition, due to the symmetrical circuit design, there is no need to distinguish polarity for both lightning current signal discharge and normal APL signal transmission, which makes installation and maintenance more convenient.

[0044] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. An APL surge protector, characterized in that: include: Surge protection circuit and leakage current alarm circuit; The surge protection circuit includes a coupling component and a transient suppression diode connected in parallel between the APL signal input terminal and the signal output terminal; The leakage current alarm circuit includes an alarm indication circuit and an alarm output circuit. The alarm indication circuit is connected in parallel to both ends of the transient suppression diode and is used to detect the leakage current of the transient suppression diode and issue a photoelectric alarm. The alarm output circuit is connected to the current output end of the transient suppression diode, and when the leakage current of the transient suppression diode reaches the level driving the contact of the alarm output circuit to close, the alarm output circuit outputs an alarm signal to the outside; Wherein, the alarm indication circuit includes a diode bridge, a resistor and a photodiode, the first end of the diode bridge is connected to the current output end of the transient suppression diode, the second end of the diode bridge is connected to the APL signal output end, the third end of the diode bridge is connected to the resistor, and the fourth end of the diode bridge is connected to the current input end of the transient suppression diode; the resistor is connected in series with the photodiode and then connected to the current input end of the transient suppression diode.

2. The APL surge protector according to claim 1, characterized in that: Two ends of the transient suppression diode are connected to a diode assembly, and the diode assembly is used to achieve normal output of the APL signal without distinguishing between positive and negative poles.

3. The APL surge protector according to claim 2, characterized in that: The diode assembly includes a first diode group, a second diode group, a third diode group, and a fourth diode group. The first diode group connects the first end of the APL signal input and the current input end of the transient suppression diode. The second diode group connects the second end of the APL signal input and the current input end of the transient suppression diode. The third diode group connects the current output end of the transient suppression diode and the first end of the APL signal output. The fourth diode group connects the current output end of the transient suppression diode and the second end of the APL signal output. The first end and the second end of the APL signal input are the positive and negative ends of the APL signal input, and the first end and the second end of the APL signal output are the two ends corresponding to the first end and the second end of the APL signal input, respectively.

4. The APL surge protector according to claim 1 or 3, characterized in that: The coupling component includes a gas discharge tube and a varistor connected in parallel, wherein the first inductor and the third inductor are connected in series at both ends of the gas discharge tube and the varistor, and the second inductor and the fourth inductor are connected in series at both ends of the varistor and the transient suppression diode.

5. The APL surge protector according to claim 4, characterized in that: When a forward lightning current is input, the discharge current path flowing through the transient suppression diode is: APL signal input first end→first inductor→second inductor→first diode group→transient suppression diode→alarm output circuit→fourth diode group→fourth inductor→third inductor→APL signal input second end.

6. The APL surge protector according to claim 4, characterized in that: When a negative lightning current is input, the discharge current path flowing through the transient suppression diode is: APL signal input second end→third inductor→fourth inductor→second diode group→transient suppression diode→alarm output circuit→third diode group→second inductor→first inductor→APL signal input first end.

7. The APL surge protector according to claim 5, characterized in that: If the transient suppression diode is damaged, leakage current will be generated when the APL signal flows in. The flow path of the APL signal is: APL signal input first end → first inductor → second inductor → second end and third end bridge arm of the diode bridge → resistor → light emitting diode → transient suppression diode → alarm output circuit → first end and fourth end bridge arm of the diode bridge → fourth inductor → third inductor → APL signal input second end.

8. The APL surge protector according to claim 6, characterized in that: If the transient suppression diode is damaged, leakage current will be generated when the APL signal flows in. The flow path of the APL signal is: the second end of the APL signal input → the third inductor → the fourth inductor → the fourth end and the third end bridge arm of the diode bridge → the resistor → the light-emitting diode → the transient suppression diode → the alarm output circuit → the first end and the second end bridge arm of the diode bridge → the second inductor → the first inductor → the first end of the APL signal input.

9. The APL surge protector according to claim 1, characterized in that: The protection voltage of the transient suppression diode is greater than 50V.

10. The APL surge protector according to claim 1, characterized in that: The APL surge protector is installed on the trunk line from the power switch to the field switch, and / or installed on the branch line from the field switch to the field APL instrument.

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