JP2011091915A - Lighting arrester - Google Patents

Abstract

A lightning arrester that can use a varistor until the end of its life and can reliably protect each terminal from surge while maintaining communication between the lightning arrester and each terminal.
A lightning arrester 1 connected to a communication line L in a communication system in which terminals 2 to 4 are connected via a pair of communication lines L conducts a surge current when a surge occurs in the communication line L. A varistor 11 connected to the communication line L bypassed to ground, a CPU 14 that detects the occurrence of a surge from the surge current flowing through the varistor 11, generates surge information, and calculates the life of the varistor 11 based on the surge information; A communication drive circuit 16 that is connected to the communication line L and exchanges signals with each of the terminals 2 to 4 via the communication line L, and a normally closed connection between the varistor 11 and the communication drive circuit 16 on the communication line L. And a relay drive circuit 18 that opens the relay 17 when the lifetime falls below the threshold value by comparing the lifetime with a predetermined threshold value.
[Selection] Figure 1

Description

  The present invention relates to a lightning arrester.

  Conventionally, when a surge voltage exceeding a predetermined voltage is applied to a pair of communication lines in a communication system in which one or more terminals are connected via a communication line, a surge current is grounded. A lightning arrester is provided to bypass.

  As an example of the lightning arrester, a varistor having one end connected to the communication line and the other end connected to the ground, a temperature fuse interposed between the communication line and the varistor, and fusing detection for detecting fusing of the temperature fuse 2. Description of the Related Art A lightning arrester including a circuit and a notification device that issues an alarm when a fusing detection circuit detects fusing of a thermal fuse is known (see, for example, Patent Document 1).

  The lightning arrester increases the leakage current when the varistor deteriorates due to an increase in the number of surge absorption of the varistor, etc., and the varistor abnormally generates heat as the leakage current increases, and the heat is transferred to the thermal fuse. Fuse the thermal fuse. Then, the fusing detection circuit detects the fusing of the thermal fuse, and the alarm notifies the alarm of the varistor abnormality, prompting the user to replace the varistor.

  However, since the lightning arrester is disconnected from the communication line when the varistor is damaged and an alarm is issued, before the varistor is replaced, a surge occurs and a surge voltage is applied to the communication line. Each terminal is damaged when the surge voltage is applied.

  Therefore, as a lightning arrester that can protect each terminal connected to one end of the communication line from a surge input from the other end of the communication line at the lifetime of the varistor, one end is connected to the communication line and the other end is connected to the ground Connected to a communication line, a current sensor that detects a surge current flowing through the varistor, measures and outputs a current value of the surge current, a comparison circuit that compares the current value with a predetermined threshold value, and a communication line A communication drive circuit that transmits / receives signals to / from each terminal via the communication line, and one end side (surge application area) of the communication line that is provided between the communication drive circuit and the terminal to input a surge and each terminal There is known a lightning arrester having a normally closed switch element that is switched off when a surge current flowing through a varistor is larger than a threshold value by switching a conduction state with the other end side of the communication line to which the

  The surge arrester protects each terminal from surge by bypassing the surge current to ground when a surge voltage is applied to the communication line, and when the surge current flowing through the varistor exceeds a predetermined threshold once The switch element is opened and each terminal is disconnected from the surge application area. Thereby, even if the varistor is damaged by a surge current exceeding the first threshold, each terminal can be prevented from being damaged by the second and subsequent surges.

JP 2008-295254 A

  However, in the lightning arrester in the above conventional example, when a surge current exceeding the threshold value flows once through the varistor, the switch element is opened regardless of the life of the varistor and the varistor needs to be replaced. Even if this is the case, the varistor was replaced and was not economical. Thus, it has been desired to improve the life judgment accuracy of the varistor.

  In addition, since the communication drive circuit is connected to the surge application area side of the communication line, there is a risk that the communication drive circuit may be damaged by a surge when the switch element is opened. Further, when the switch element is opened, the lightning arrester There is a problem that communication with each terminal becomes impossible.

  The present invention has been made in view of the above reasons, and its purpose is to accurately determine the life of a varistor and use the varistor until the end of its life, and maintain communication between the lightning arrester and each terminal. On the other hand, it is an object of the present invention to provide a lightning arrester capable of reliably protecting each terminal from surge until the varistor is replaced.

  The invention of claim 1 is connected to a pair of communication lines in a communication system in which one or more terminals are connected via a pair of communication lines, and a surge voltage exceeding a predetermined voltage is applied to the communication lines. A lightning arrester that bypasses the surge current to the ground in the case, and circuit protection means connected to the communication line that conducts and bypasses the surge current to the ground when a surge voltage exceeding a predetermined voltage is applied to the communication line; A life calculation means for detecting the occurrence of a surge from a surge current flowing through the circuit protection means, generating surge information relating to the surge, and calculating a life of the circuit protection means based on the surge information; and connected to a communication line A communication means for exchanging signals with each terminal via the communication line; a normally closed switch means provided between the circuit protection means and the communication means on the communication line; Characterized in that the lifetime of the device is composed of a connection switching means for opening the switch means when it reaches a predetermined threshold.

  According to this invention, the circuit protection means can be used until the end of the life by accurately obtaining the life of the circuit protection means based on the history of surge information, and the life is smaller than a predetermined threshold value. In this case, by automatically opening the switch means provided between the circuit protection means and the communication means, each terminal is reliably protected from surge until the varistor is replaced while maintaining the communication between the lightning arrester and each terminal. can do.

  According to a second aspect of the present invention, in the first aspect of the present invention, the switching means is switched between open and closed states based on a switching signal transmitted from a terminal.

  According to the present invention, the switch means can be opened and closed by the user's intention by remote operation from the terminal, and communication can be intentionally disconnected / recovered.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the connection switching means sets the threshold based on a threshold setting signal transmitted from a terminal.

  According to the present invention, the threshold value can be appropriately set according to the environment where the lightning arrester is installed and the performance of the circuit protection means by remote control from the terminal.

  As described above, in the present invention, each varistor can be used until the varistor is replaced while maintaining the communication between the lightning arrester and each terminal while maintaining the communication between the lightning arrester and each terminal by accurately obtaining the lifetime of the varistor. It is possible to provide a lightning arrester capable of reliably protecting against surge.

The schematic block diagram of the communication system with which the lightning arrester of this embodiment was connected is shown.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
For example, as shown in FIG. 1, the lightning arrester 1 of the present embodiment includes a display terminal 2 that displays the state of the lightning arrester 1, an operation terminal 3 that performs operation input to the lightning arrester 1, Used in a communication system including a transmission unit 4 connected via a pair of communication lines L and controlling communication between the terminals 2 and 3, a surge voltage exceeding a predetermined voltage is applied to the communication lines L When conducting, bypass the surge current to ground. Here, the lightning arrester 1 is connected to one end side of the communication line L, and the terminals 2 and 3 and the transmission unit 4 are connected to the other end side of the communication line L. The lightning arrester 1 protects the terminals 2 and 3 and the transmission unit 4 from a surge input to the communication line L from one end of the communication line L.

  As shown in FIG. 1, the lightning arrester 1 detects a surge current value by detecting a surge current flowing through the varistor 11 and a varistor (circuit protection means) 11 having one end connected to the communication line L and the other end connected to the ground. Based on the current sensor 12 that is measured and output, the A / D converter 13 that converts analog data of the surge current value output from the current sensor 12 into digital, and the surge current value output from the A / D converter 13 Communication having an interface function for exchanging signals between the CPU 14 that calculates the lifetime of the varistor 11 and generates surge information including the lifetime information, a memory (storage means) 15 that stores surge information, and the communication line L Drive circuit 16, relay 17 (switch means) provided between varistor 11 and communication drive circuit 16 on communication line L, and life of varistor 11 There consists advance relay driving circuit (connection switching means) for driving the relay 17 when below a set threshold 18..

  The varistor 11 is connected to the communication line L and the ground. When the surge voltage higher than a predetermined voltage is applied to the communication line L, the varistor 11 is turned on and bypasses the surge current to the ground, thereby being applied to the communication line L. Surge voltage is suppressed, and the terminals 2, 3 and the transmission unit 4 are protected from the surge. Here, the circuit protection element such as the varistor 11 deteriorates as the number of surge absorption increases, and the surge absorption capability decreases. Therefore, it is necessary to replace the circuit protection element before the surge cannot be absorbed (the varistor reaches the end of its life).

  The current sensor 12 is composed of, for example, a coil surrounding a lead wire connecting the other end of the varistor 11 and the ground, and outputs an analog signal of a surge current value flowing through the lead wire.

  The A / D converter 13 digitally converts an analog signal of a surge current value input from the current sensor 12 and outputs the analog signal.

  The CPU 14 determines the remaining life (lifetime) of the varistor 11 obtained by calculation from the surge current value input from the A / D converter 13, the surge occurrence time, the number of surge detections, the history of surge information stored in the memory 15, and the like. Information) is generated (life calculation means). Here, the CPU 14 determines that the varistor 11 is damaged according to the magnitude of the surge current flowing through the varistor 11, and performs an operation so that the longer the damage is, the shorter the remaining life is.

  Then, the CPU 14 compares the remaining life with a preset threshold value. When the remaining life is larger than the threshold value, the CPU 14 outputs surge information to the memory 15 and then inputs the surge current value. Wait until.

  Further, when the remaining life becomes smaller than a preset threshold value, the CPU 14 outputs a drive signal to the relay drive circuit 18. In the present embodiment, the remaining life of the varistor 11 is compared with the threshold value. However, the cumulative damage of the varistor 11 is obtained by calculation based on the surge information, and the relay is relayed when the cumulative damage exceeds the threshold value. A drive signal may be output to the drive circuit 18.

  The relay drive circuit 18 is connected to an excitation winding of a relay 17 having a so-called normally closed contact 171 and an excitation winding 172. When a drive signal is inputted, the excitation winding 172 is energized by energization. Each contact 171 provided on each of the pair of communication lines L is opened.

  For this reason, the communication line L includes a region where the surge voltage on the varistor 11 side is applied across the contact 171 (surge application region) across the contact 171 when the life of the varistor 11 approaches and a surge occurs. Since the contacts 171 closer to the terminals 2 and 3 than the terminal 171 are opened, the terminal is divided into regions where no surge voltage is applied (surge non-application region). Therefore, when the life of the varistor 11 approaches, the contact 171 is opened, so that even if a surge is input to the communication line L, a surge voltage is applied to the communication line L on the terminals 2 and 3 side. Instead, each terminal 2, 3 and the transmission unit 4 are protected from surges.

  In addition, since the communication drive circuit 16 is connected to the communication line L on the terminals 2 and 3 side (surge non-applying region) from the contact 171, even after the contact 171 is opened, the lightning arrester 1 and Communication with each terminal 2, 3 and transmission unit 4 is maintained.

  Therefore, the lightning arrester of the present embodiment can use the varistor 11 until the end of its life, and when the life of the varistor 11 becomes smaller than a predetermined threshold (when the life of the varistor 11 approaches), And the communication drive circuit 16 are automatically opened, so that the communication between the lightning arrester 1 and each of the terminals 2 and 3 and the transmission unit 4 is maintained and the varistor 11 is replaced until the varistor 11 is replaced. The terminals 2 and 3 and the communication drive circuit 16 can be reliably protected from surge.

  In addition, when a surge occurs and a surge current value is input, the CPU 14 sends surge information including updated life information to the communication line L via the communication drive circuit 16. The surge information sent to the communication line L is sent to the display terminal 2 via the transmission unit 4. In the present embodiment, surge information including the life information of the varistor 11 is transmitted from the lightning arrester 1 to the display terminal 2, but for a server (not shown) that integrates a plurality of lightning arresters 1 connected to the communication line L. By transmitting the surge information, it is possible to update only the life information of the varistor 11 that has been exchanged from the life information of each varistor 11 stored in the server.

  The display terminal 2 includes a communication drive circuit 21 having an interface function for transmitting and receiving signals to and from the communication line L, a control unit 22 that controls each unit in the display terminal 2, an LCD displayed by the control unit 22, and the like And a memory 24 for storing surge information received via the communication drive circuit 21, and the control unit 22 generates display data based on the surge information input via the communication drive circuit 21. Then, the remaining life of the varistor 11 is displayed on the display unit 24 based on the display data.

  Then, the user can confirm the state of the varistor 11 by confirming the display unit 24 of the display terminal 2, and when the display indicating that the life of the varistor 11 is approaching is made, Exchange. After replacing the varistor 11, the user can press the reset button (not shown) provided on the lightning arrester 1 to close the contact 171 and restore communication, and is stored in the memory 15. Surge information can be initialized. Further, when the reset switch is pressed, the lightning arrester 1 resets the surge information related to the exchanged varistor 11 stored in each of the display terminal 2 and the server to the display terminal 2 and the server. A signal is transmitted.

  The operation terminal 3 includes a communication drive circuit 31 having an interface function for transmitting and receiving signals to and from the communication line L, an operation unit 32 including switches and buttons operated by a user, and control of each unit in the operation terminal 3 A control unit 33 that performs switching, and when the switch of the operation unit 32 is turned on / off by the user, an open / close switching signal that instructs the lightning arrester 1 to open / close the contact 171 from the operation terminal 3 via the transmission unit 4 Sent. In the lightning arrester 1 that has received the open / close switch signal, the drive signal output from the CPU 14 to the relay drive circuit 18 is turned on / off based on the open / close switch signal, and the contact 171 is opened / closed. Thus, the contact 171 can be opened and closed by the user's intention by remote operation from the operation terminal 3 to switch the communication recovery / disconnection, and the contact 171 can be opened proactively or as described above. When the contact 171 is automatically opened, the contact 171 can be intentionally closed to restore communication.

  Further, the threshold used by the CPU 14 when determining the life can be changed by a dial switch or the like provided in the operation unit 32 of the operation terminal 3. Specifically, each time the user operates the dial switch, a threshold setting signal corresponding to the position of the dial switch is transmitted to the lightning arrester 1 via the transmission unit 4, and the lightning arrester 1 receives the received threshold setting signal. The threshold value is changed accordingly. Thereby, the threshold value can be appropriately set according to the environment in which the lightning arrester 1 is installed and the performance of the varistor 11 by remote control from the operation terminal 3.

1 Lightning Arrester 2 Display Terminal 3 Operation Terminal 4 Transmission Unit 11 Varistor (Circuit Protection Means)
12 Current sensor 13 A / D converter 14 CPU (lifetime calculation means)
15 Memory (memory means)
16 Communication drive circuit (communication means)
17 Relay (switch means)
18 Relay drive circuit (connection switching means)
L Communication line

Claims (3)

When one or more terminals are connected to a pair of communication lines in a communication system connected via a pair of communication lines and a surge voltage exceeding a predetermined voltage is applied to the communication lines, the surge current is grounded. A lightning arrester to bypass,
Circuit protection means connected to the communication line that bypasses surge current to ground when a surge voltage exceeding a specified voltage is applied to the communication line, and the occurrence of surge is detected from the surge current flowing in the circuit protection means Generating surge information related to the surge, calculating the lifetime of the circuit protection means based on the surge information, and transmitting and receiving signals to and from each terminal connected to the communication line A communication means, a normally closed switch means provided between the circuit protection means and the communication means on the communication line, and a connection switching means for opening the switch means when the life of the circuit protection means reaches a predetermined threshold value. A lightning arrester characterized by comprising.   2. The lightning arrester according to claim 1, wherein the switch means is switched between open and closed states based on a switching signal transmitted from a terminal. The lightning arrester according to claim 1 or 2, wherein the connection switching means sets the threshold based on a threshold setting signal transmitted from a terminal.

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