JP4196026B2 - Lightning strike detection circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention discriminates a lightning approaching state used in a lightning protection device for protecting a device connected to a communication signal line and / or a low voltage power line from a lightning surge entering from the communication signal line or the low voltage power line. The present invention relates to an improved lightning strike detection circuit.
[0002]
[Prior art]
Commercial frequency low-voltage power lines are usually stepped down from high-voltage distribution lines to 100V by pole transformers and wired into buildings such as ordinary households, and are connected to electrical equipment and communication signal lines such as refrigerators, washing machines, and air conditioners. It also supplies electricity to connected electrical equipment such as TVs, telephones, facsimiles and personal computers.
Lightning surges occur in low-voltage power lines or communication signal lines due to lightning strikes on high-voltage distribution lines, etc., and lightning surges propagate through power lines or communication lines and enter buildings, and are connected to these lines. It is known to destroy existing electrical equipment.
In order to protect these electric devices, for example, a lightning surge protection device that detects an abnormal voltage caused by a lightning surge and sends a control signal to display a lightning strike alarm or the like has been proposed. (For example, refer to Patent Document 1.)
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-326108 (page 2-3, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, lightning discharges may occur not only from those approaching from a distance, but also suddenly, and it is determined whether there is lightning approach that can handle both those approaching from a distance and this sudden close lightning discharge. What is desired is a lightning protection device having a discriminating circuit.
[0005]
In addition, if a failure occurs in the intrusion detection circuit from the detection circuit that detects lightning discharge to the determination circuit that determines the approach of lightning, erroneous detection may occur and the protected device may be damaged or unnecessary operations may occur. May occur,
Therefore, an inexpensive self-diagnosis circuit that can make a self-judgment of whether or not the entire circuit is faulty is desired, but when the lightning surge detection means receives lightning noise radio waves using a grounded antenna, the antenna is included. There is a problem that it is difficult to easily self-diagnose the presence or absence of a failure in the entire lightning strike detection circuit.
[0006]
[Means for Solving the Invention]
The present invention has been made to solve the above problems,
In the lightning strike detection circuit used in the lightning protection device that compares the lightning surge detection signal detected by the lightning surge detection means with the judgment value to determine the approach of lightning,
A first discriminating circuit for discriminating that a lightning is approaching when the judgment value is greater than or equal to a predetermined first level value and a predetermined number of lightning surges occur within a predetermined time; and the determination value is greater than the first level value A second discrimination circuit that is set to a high predetermined second level value and immediately discriminates that lightning is approaching when a lightning surge of the second level or higher occurs, the first discrimination circuit and the second discrimination circuit When one of them is determined to be approaching lightning, it is determined that lightning is approaching, and the detection means is a grounded antenna, and a simulated signal generation circuit for confirming the presence or absence of failure of the lightning detection circuit is connected to the antenna. An attack used for a lightning protection device, characterized in that a simulated signal is generated between the connection point and the ground by inserting and connecting between the connection point of the received tank circuit for receiving tuning and the ground. It is a lightning detection circuit.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the lightning strike detection circuit 1 includes a lightning surge detection circuit 2, a first discrimination circuit 3 for discriminating lightning approach to a lightning approaching gradually from a distance, and a lightning strike against a rapidly developed thundercloud. It comprises a discrimination circuit 5 provided with a second discrimination circuit 4 for discriminating approach,
The lightning surge signal detected by the lightning surge detection circuit 2 is sent to the discrimination circuit 5, and the discrimination circuit 5 discriminates the presence or absence of lightning, and the discrimination result is transmitted to the output circuit 6.
[0010]
The output circuit 6 performs a lightning approach notification, a protection operation of the protected device, etc., based on the output signal of the lightning approach state transmitted from the lightning detection circuit 1.
Examples include a lightning strike alarm, disconnection of protected equipment from a power line or communication line, switching to an emergency power source, insertion of a lightning resistant transformer into the power line, and the like.
When the lightning approach is released, alarm stop, connection of protected equipment to the power line and communication line, disconnection of the lightning resistant transformer to the power line, etc. are automatically performed.
[0011]
The operation of the determination circuit 5 will be described.
A lightning surge signal as shown in FIGS. 3 and 4 is detected by the lightning surge detection circuit 2 and sent to the first determination circuit 3 and the second determination circuit 4 simultaneously.
[0012]
For example, the first determination circuit 3 uses the L1 level of the lightning surge signal level as a determination value as shown in FIG. 3, determines whether the lightning surge signal is equal to or higher than a predetermined L1 level as shown in FIG. When the level is equal to or higher than the level, measurement of a predetermined time Ta (10 minutes) is started, and the number of occurrences of lightning surge signals of the L1 level or higher occurring within the time Ta is counted by a counter. 3) When it becomes above, it judges that it is a thunder approaching state and sends an output signal.
The counter is reset after the time Ta has elapsed.
[0013]
The time Ta and the determination value n are a time and count value for discriminating lightning surge and noise, and it is sufficient that the time Ta and the determination value n are set to the time and number that can identify the lightning surge that occurs continuously. It is not limited to the numerical values in the examples.
Further, the count value can be multiplied by a coefficient set in advance according to the signal level, and the magnitude of each signal level can be added to the determination of the lightning approaching state.
[0014]
In this way, the first discrimination circuit 3 can discriminate lightning approach to lightning that gradually approaches from far away, and protect the protected device from lightning damage.
Next, the second determination circuit 4 uses, for example, the L2 level at which the lightning surge signal level is set higher than the L1 level as shown in FIG. 4 as the determination value, and the lightning surge signal as shown in FIG. Is determined to be equal to or higher than the L2 level, and if it is equal to or higher than the L2 level, it is immediately determined that the lightning is approaching and an output signal is transmitted.
[0016]
As described above, the second determination circuit 4 can determine that the lightning is approaching even for a suddenly developed lightning, and can output an output signal, thereby protecting the protected device from lightning damage. .
[0017]
Based on the output of the lightning approaching state from the first discrimination circuit 3 or the second discrimination circuit 4, the lightning strike detection circuit 1 has no lightning surge signal of the L1 level or more and is equal to or longer than the time Ta. A lightning approaching state signal is transmitted to the output circuit 6 until a predetermined time Tb has elapsed.
[0018]
The time Tb is a time for stopping the alarm and returning the protected device, and is set to a time when the safety time is expected after the lightning surge disappears.
After the time Tb has elapsed, the lightning approach is released.
Time Ta and time Tb are measured by the timer A, and the timer A is reset every time a signal of the L1 level or higher is detected.
[0019]
In this embodiment, the time Ta and the time Tb are timed by the timer A, but the time is not limited to the timer as long as the predetermined time can be measured, and a known time measuring means can be used. Time Ta and time Tb may be measured separately.
Further, in this embodiment, the relationship of time Tb ≧ time Ta is established, but time Tb <time Ta may be set.
[0020]
Although FIG. 1 shows the case of the grounded antenna 11 as the lightning surge detection circuit 2, the lightning surge detection circuit 2 includes a method for detecting a lightning surge signal flowing in the line by CT or PT, a thundercloud electric field, and the like. It is also possible to use a detection circuit such as a method for detecting a lightning with an electrostatic field sensor, as long as it can detect a lightning surge and is not limited to FIG.
[0021]
Next, it will be described that the failure of the entire circuit including the connection with the grounded antenna 11 can be confirmed by the simulation signal E2 generated by the simulation signal generation circuit 16. FIG.
When the antenna 11 is receiving a lightning surge signal, as shown in FIG. 5, the reception tuning tank circuit 13 from the grounded antenna 11 is received by the received signal E1 received by the grounded antenna 11. Current i will flow through.
Rr represents the radiation resistance of the antenna, and Xa represents the reactance of the antenna.
[0022]
Similarly, as shown in FIG. 1, the simulation signal E2 generated by the simulation signal generation circuit 16 inserted and connected to the grounding antenna 11 and the ground line of the reception tuning tank circuit 13 is generated as shown in FIG. As shown sometimes, since a signal can be generated between the tank circuit 13 and the ground line, the value of the simulation signal E2 is set to an appropriate value, so that Rr and Xa of the antenna 11 pass through the tank circuit 13. The same current i as in reception can be passed through the closed circuit.
[0023]
That is, when the antenna 11 is out of order, the numerical values of the radiation resistance Rr and the reactance Xa of the antenna 11 change. Therefore, even if the same simulated signal E2 is generated, the numerical value of the current i flowing through the closed circuit changes. The presence or absence of a failure can be easily confirmed.
Therefore, the simulation signal generation circuit 16 can confirm whether or not the entire circuit including the connection state of the antenna 11 has a failure, thereby preventing erroneous determination due to the circuit failure.
[0024]
A specific circuit example of the simulation signal generating circuit 16 is shown in FIG.
Normally, the switch S is connected to the e side, and when diagnosing the presence or absence of a failure, the switch S is switched to the k side.
By switching to the k side, the simulation signal E2 is inserted between the tank circuit 13 and the ground line, and the reception signal E1 generated by reception is generated regardless of the connection length with the antenna 11. Exactly the same phenomenon can be generated in the circuit.
[0025]
R1 and R2 are resistances for adjusting the simulation signal E2 value. Since a voltage shared by R1 and R2 of the voltage E3 is generated at both ends of the resistance R1, an arbitrary simulation signal E2 is generated by a combination of R1 and R2. Can be generated.
The capacitor C1 is for limiting the rise of the rectangular wave voltage to prevent the generation of an unnecessarily high frequency component, and may be omitted.
[0026]
The simulation signal E2 is not limited to a DC voltage, and a voltage having an arbitrary waveform such as a sine wave voltage or a rectangular wave voltage can be used.
In particular, by using a sine wave voltage, there is an advantage that sensitivity characteristics including the antenna 11 and the tank circuit 13 can be easily measured.
[0027]
7 and 8 show another embodiment.
In FIG. 7, a tank circuit 13 is provided immediately below the antenna 11, and a circuit 17 for lowering the output side of the tank circuit is inserted and connected to the connection cable 12. The amplifier circuit 14, the detection circuit The received lightning surge signal is sent to the discrimination circuit 16 via the circuit 15.
The simulation signal generation circuit 16 is connected to a ground line connected to the connection cable 12, and the same components as those in FIG.
[0030]
【The invention's effect】
In the present invention, by providing a first determination circuit that determines a lightning approach when the determination value is equal to or higher than the first level value and a predetermined number of lightning surges occur within a predetermined time, the distance is gradually increased. It is possible to discriminate lightning approach without making a misjudgment with respect to a lightning approaching from the first, and to immediately determine that lightning is approaching when a lightning surge exceeding a second level value higher than the first level value occurs. Because the two-discriminating circuit can immediately determine the approach of lightning even to a rapidly developed thundercloud, the protected device can be more reliably protected from lightning damage.
Furthermore, by inserting and connecting the simulated signal generation circuit between the ground side connection point of the tank circuit connected to the antenna and the ground, it is possible to easily check whether there is a failure in the entire circuit including the connection state of the antenna. It is possible to detect a failure of the lightning detection circuit early.
Therefore, misjudgment due to failure can be prevented in advance, a lightning detection circuit free from misjudgment due to failure can be provided, and the protected device can be more reliably protected from lightning damage.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of a determination circuit 5;
FIG. 3 is an operation explanatory diagram of FIG. 2;
FIG. 4 is another operation explanatory diagram of FIG. 2;
FIG. 5 is a diagram illustrating the principle of a simulation signal generation circuit 16;
FIG. 6 is a circuit explanatory diagram of a simulation signal generation circuit 16;
FIG. 7 is an explanatory diagram of another embodiment.

Claims (1)

In the lightning strike detection circuit used in the lightning protection device that compares the lightning surge detection signal detected by the lightning surge detection means with the judgment value to determine the approach of lightning,
A first discriminating circuit for discriminating that a lightning is approaching when the judgment value is greater than or equal to a predetermined first level value and a predetermined number of lightning surges occur within a predetermined time; and the determination value is greater than the first level value A second discrimination circuit that is set to a high predetermined second level value and immediately discriminates that lightning is approaching when a lightning surge of the second level or higher occurs, the first discrimination circuit and the second discrimination circuit When one of them is determined to be approaching lightning, it is determined that lightning is approaching, and the detection means is a grounded antenna, and a simulated signal generation circuit for confirming the presence or absence of failure of the lightning detection circuit is connected to the antenna. An attack used for a lightning protection device, characterized in that a simulated signal is generated between the connection point and the ground by inserting and connecting between the connection point of the received tank circuit for receiving tuning and the ground. Lightning detection circuit.

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