JP2004194409A - Lightning damage protection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact lightning damage protection system of low cost wherein thunder attack information is detected from a low voltage line without using an especially expensive coupling capacitor, and connection/isolation of a thunder resistant transformer are performed to an electric path, so that power dissipation of the thunder resistant transformer can be eliminated. <P>SOLUTION: The lightning damage protection system is provided with the thunder resistant transformer, an opening and closing mechanism which performs connection/isolation of the thunder resistant transformer to the electric path, and a lightning surge detector for detecting approach of thunder attack. The system operates the opening and closing mechanism by a signal from the lightning surge detector, performs connection/isolation of the thunder resistant transformer to the electric path, and grounds a shield and a core of the thunder resistant transformer. In the system, the lightning surge detector is arranged on an earthing wire of the shield and/or the core. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning protection system provided with a lightning protection transformer for protecting electronic devices from lightning surge generated by a lightning strike that enters from a commercial frequency power supply line. The present invention relates to an improvement of a lightning protection system in which a lightning protection transformer is connected to an electric circuit when lightning is approaching, so that power loss of the lightning protection transformer is minimized.
[0002]
[Prior art]
Conventionally, it has been known that a lightning surge generated by a lightning strike propagates through a commercial frequency power supply line and enters a building, thereby destroying electrical devices and the like connected to the power supply line. Various protection systems have been proposed in order to protect a computer.
As one of them, a protection system has been proposed in which a lightning-resistant transformer is installed at an entrance of a commercial frequency power supply line into a room to prevent a lightning surge from entering the building from the power supply line. (For example, refer to Patent Document 1.)
[0003]
However, since the power loss due to iron loss and the like in the above lightning-resistant transformer is as large as about 3 to 10% of the transformer capacity, there is a demand that the lightning-resistant transformer be disconnected from the power supply line except when the lightning is approaching and when the lightning is approaching. is there.
[0004]
Accordingly, the present applicant has proposed in Japanese Patent Application No. 2002-204756 a lightning proof system in which the lightning storm is detected first, and the lightning proof transformer is connected to the electric circuit only when the lightning is approaching, thereby eliminating the power loss of the lightning proof transformer. I have.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 7-89712 (Pages 4-5, Fig. 1)
[0006]
[Problems to be solved by the invention]
As a method of detecting a lightning strike in the lightning resistant system, there are a method of measuring lightning light, thunder, electromagnetic waves, an electrostatic field, and the like with various sensors, and a method of providing a lightning surge propagating on the low-voltage line between the low-voltage line and the ground. It is generally known to perform detection by a detector such as CT via a capacitor.
[0007]
By the way, in the above-mentioned detection method in which the coupling capacitor is provided, the lightning surge flowing through the low-voltage line is directly detected through the coupling capacitor. When a lightning surge overvoltage is directly applied to the power supply, an insulation breakdown may occur and the power supply may be damaged, and as a countermeasure, an expensive capacitor having a high withstand voltage has been used.
At the same time, there is a problem that the size of the device is increased due to the coupling capacitor.
[0008]
The present invention has been made in order to solve the above-mentioned problems in the detection method provided with the coupling capacitor, and reliably detects lightning strike information from a low voltage line without using an expensive coupling capacitor. Another object of the present invention is to provide an inexpensive and compact lightning protection system capable of connecting / disconnecting a lightning-resistant transformer to / from an electric circuit and eliminating power loss of the lightning-resistant transformer.
[0009]
Means for Solving the Invention
The present invention has been made to solve the above problems,
The invention according to claim 1 includes a lightning proof transformer, an opening / closing mechanism for connecting / disconnecting the lightning proof transformer to / from an electric circuit, and a lightning surge detector for detecting approach of a lightning strike,
The lightning surge detector operates the switching mechanism in response to a signal from the lightning surge detector to connect / disconnect the lightning proof transformer to / from an electric circuit, and further grounds a shield wire and an iron core of the lightning proof transformer with a ground wire. In the harm protection system,
The lightning protection system is characterized in that the surge detector is provided on the ground wire.
[0010]
According to a second aspect of the present invention, a shield provided between the primary coil and the secondary coil and a primary coil and a secondary coil are wound to prevent lightning surge from propagating from the primary coil to the secondary coil. A lightning proof transformer comprising a mounted iron core, an opening / closing mechanism for connecting / disconnecting the lightning proof transformer to / from an electric circuit, and a lightning surge detector for detecting approach of a lightning attack,
The lightning surge detector operates the switching mechanism in response to a signal from the lightning surge detector to connect / disconnect the lightning proof transformer to / from an electric circuit, and further grounds a shield wire and an iron core of the lightning proof transformer with a ground wire. In the harm protection system,
A lightning protection system, wherein a detector for detecting a lightning surge flowing through the ground line is provided on the ground line.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an embodiment (normal state) of the present invention,
Reference numeral 10 denotes a low-voltage service line, which is connected to a low-voltage distribution line that is stepped down to a commercial frequency of 100 V or 200 V by a transformer installed on a pole installed outdoors.
[0012]
Reference numeral 20 denotes an indoor wiring in a building, which is connected to a power terminal of an electric device used in a general home or office, such as a TV, a video, a telephone, a facsimile, a computer, a washing machine, a microwave oven, and an air conditioner.
[0013]
Numeral 30 denotes a lightning-resistant transformer having a shield wire 33, as shown in FIG. 4, having a structure in which a primary coil 31, a shield 33, and a secondary coil 32 are wound around an iron core 30b.
[0014]
As shown in FIG. 1, the lightning transformer 30 is connected / disconnected between the primary coil 31 of the lightning transformer 30 and the low-voltage drop wire 10 and between the secondary coil 32 of the lightning transformer 30 and the indoor wiring 20 as shown in FIG. A switching device 40 provided with contacts 41 and 42 and a bypass line 43 for performing the operation is provided.
[0015]
The contacts 41 and 42 are operated in conjunction with each other by a drive mechanism (not shown) of a switchgear 40 which is operated by a signal from a control device 55 to be described later, and connects the low-voltage drop wire 10 and the indoor wiring 20 to the lightning transformer 30 by a bypass line 43. The electrical equipment connected to the indoor wiring 20 can be switched between a normal state in which the electrical equipment is connected without any intervention and a lightning-resistant state in which the electrical equipment is connected via the lightning-resistant transformer 30 without interruption.
[0016]
Note that switching in the uninterruptible state refers to a state in which information in a memory or the like of an electric device is switched without being erased or in a reset state after switching.
[0017]
Further, the secondary side N-phase terminal 32b of the lightning protection transformer 30, the bypass line secondary side N-phase terminal 43b of the switchgear 40, and the N-phase 20b of the indoor wiring 20 are electrically connected without any contact. Has become.
[0018]
In this embodiment, the secondary-side N-phase terminal 32b of the lightning protection transformer 30, the bypass-line secondary-side N-phase terminal 43b of the switchgear 40, and the N-phase 20b of the indoor wiring 20 are always electrically connected without providing a contact. Although they are connected, the phases that are always connected are not limited to the present embodiment, and the secondary U phase 32a, the secondary V phase 32c, the primary U phase 31a, and the primary V phase Any of the primary phase 31c and the primary-side N phase 31b may be used, and any one phase can be used.
[0019]
In this case, since there is only one connection point (one phase) to the lightning protection transformer 30, no current flows through the primary coil 31 or the secondary coil 32 of the lightning protection transformer 30 even if the connection is made. Thus, even if the connection is always made, the lightning-resistant transformer 30 does not cause power loss.
[0020]
The shield wire 33 is electrically connected to a ground 60 and a ground wire 39, and a detector 50 is connected to the ground wire 39.
[0021]
The detector 50 has a configuration in which the ground wire 39 is connected to the primary terminal of the current transformer 51, and the resonance circuit 52 is provided in the secondary terminal of the current transformer 51. It detects a lightning surge signal.
[0022]
That is, as shown in FIG. 3, since the stray capacitance 30 a exists between the primary coil 31 or the secondary coil 32 of the lightning protection transformer 30 and the shielded wire 33,
The lightning surge signal that has entered from the low-voltage drop line 10 is transmitted to the primary coil 31 of the lightning protection transformer 30 that is always directly connected to the low-voltage drop line 10 or the secondary coil 32 that is connected to the low-voltage drop line 10 via the bypass line 43. Since the light enters the shield wire 33 via the stray capacitance 30a, it can be easily detected by providing the detector 50 on the ground wire 39 connecting the shield wire 33 and the ground 60.
[0023]
Since the withstand voltage between the primary coil 31 or the secondary coil 32 of the lightning protection transformer 30 and the shielded wire 33 is extremely high, the dielectric breakdown does not occur due to the invading lightning surge overvoltage.
[0024]
Further, in the present embodiment, the detector 50 is provided on the ground wire 39 connecting the shield wire 33 and the ground 60, but the iron core 30b of the lightning protection transformer 30 is connected to the ground 60 as shown in FIG. A lightning surge current flowing through the iron core 30b may be provided on the ground wire 38 to detect the surge current.
[0025]
That is, similarly to the shield 33, the stray capacitance 30a exists between the primary coil 31 or the secondary coil 32 of the lightning protection transformer 30 and the iron core 30b for the iron core 30b. The surge signal also flows to the iron core 30b via the primary coil 31 or the secondary coil 32 and the stray capacitance 30a, and the detector 50 is provided on the ground wire 38 connecting the iron core 30b and the ground 60. This is because it can be easily detected.
[0026]
Since the withstand voltage between the primary coil 31 or the secondary coil 32 of the lightning-resistant transformer 30 and the iron core 30b is extremely high similarly to the shield 33, the dielectric breakdown is caused by the invading lightning surge overvoltage. Nothing.
[0027]
The detector 50 extracts a signal of a frequency component having a center frequency of 12 kHz and a bandwidth of 1.1 kHz from the current flowing through the shield wire 33 and sends the signal to the control device 55.
[0028]
Note that the signal taken out by the detector 50 is not limited to the frequency band of the above-described embodiment, as long as it is a signal generated with a lightning discharge. Is also good.
[0029]
The lightning surge signal refers to a signal generated with a lightning discharge, such as a surge signal generated at the time of a precursory phenomenon of lightning discharge or a surge signal generated at the time of lightning strike.
[0030]
The control device 55 performs a lightning strike determination based on the signal detected by the detector 50, and gives a switching command to the switching device 40. The switching device 40 changes from a normal state to a lightning-resistant state by a command from the control device 55, Alternatively, the switching operation from the lightning-resistant state to the normal state is performed.
[0031]
The control device 55 compares the signal with a signal transmitted from the detector 50 in accordance with a judgment condition such as exceeding a preset danger level set value (size, duration, frequency, etc.) to determine the approach of lightning. Do.
As a result, when it is determined that there is danger, an operation command is given to the switchgear 40 to switch the contacts 41 and 42 of the switchgear 40 to the lightning proof transformer side, and the lightning proof transformer 30 shown in FIG. Switch to lightning proof.
[0032]
After a predetermined time has elapsed, the control device 55 determines that the lightning surge signal is undetected or the lightning surge signal has become equal to or less than the danger level set value and determines that the safety is safe, and switches the switching device 40 to the normal state. , An operation command is given to the switchgear 40 to disconnect the lightning proof transformer 30 from the electric circuit and return to the normal state shown in FIG.
[0033]
Note that the operation of connecting or disconnecting the lightning-resistant transformer 30 from or to the electric circuit by the switching device 40 needs to be performed in an uninterrupted state so that the electrical equipment connected to the load side does not stop. It is preferable that the instantaneous power failure time of the load-side indoor wiring 20 accompanying the operation be performed within one cycle of the commercial frequency, and more preferably within １ ／ cycle.
By performing switching within such a time period, switching can be performed in an uninterruptible state without erasing or resetting information in the memory or the like of the load-side electric device.
[0034]
As shown in FIG. 1, a surge absorber 90 made of a ZnO element may be provided between the low-voltage drop wire 10 and the indoor wiring 20 between the lines or the ground, and the surge absorber on the indoor wiring 20 side may be omitted, or a lightning-resistant transformer may be used. A surge absorber may be provided for the secondary side coil 32 of 30.
[0035]
As described above, according to the present invention, the detector 50 provided on the ground wire 39 or 38 that connects the shield wire 33 or the iron core 30b to the ground 60 converts the lightning surge signal caused by the lightning strike that enters through the low-voltage drop wire 10 into the lightning transformer. Since detection is performed using stray capacitance, lightning surge can be detected without providing a coupling capacitor for detection.
[0036]
In order to directly detect a dangerous lightning surge overvoltage signal generated in a low-voltage service line connected to a building, a lightning protection system free from erroneous detection and malfunction due to noise or the like can be provided.
[0037]
The present invention is not limited to this embodiment, and can be used to detect the approach of lightning in all lightning protection devices and lightning protection systems using transformers.
[0038]
【The invention's effect】
According to the present invention, the stray capacitance of the lightning proof transformer is used, and this is used as a substitute for the coupling capacitor for detection. Therefore, it is not necessary to use an expensive coupling capacitor having a particularly high withstand voltage performance. .
At the same time, since a coupling capacitor is not required, the size may be the same as that of the conventional lightning proof transformer, and the device can be downsized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a normal state of an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a lightning-resistant state according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing the operation principle of the present invention.
FIG. 4 is a structural sectional view of a lightning proof transformer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Low-voltage service wire 20 Indoor wiring 30 Lightning-resistant transformer 40 Switchgear 50 Detector 55 Control device 90 Surge absorber

Claims (2)

Lightning-resistant transformer,
An opening / closing mechanism for connecting / disconnecting the lightning-resistant transformer to / from an electric circuit, and a lightning surge detector for detecting approach of a lightning strike;
The lightning surge detector operates the switching mechanism in response to a signal from the lightning surge detector to connect / disconnect the lightning proof transformer to / from an electric circuit, and further grounds a shield wire and an iron core of the lightning proof transformer with a ground wire. In the harm protection system,
A lightning protection system, wherein the surge detector is provided on the ground line. Consists of a shield provided between the primary coil and the secondary coil to prevent lightning surge from propagating from the primary coil to the secondary coil, and an iron core wound with the primary coil and the secondary coil Lightning-resistant transformer,
An opening / closing mechanism for connecting / disconnecting the lightning-resistant transformer to / from an electric circuit, and a lightning surge detector for detecting approach of a lightning strike;
The lightning surge detector operates the switching mechanism in response to a signal from the lightning surge detector to connect / disconnect the lightning proof transformer to / from an electric circuit, and further grounds a shield wire and an iron core of the lightning proof transformer with a ground wire. In the harm protection system,
A lightning protection system, wherein a detector for detecting a lightning surge flowing through the ground line is provided on the ground line.

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