JP2007243450A - Ground-fault interrupter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the application of a ground-fault interrupter to a power distribution board of a general household and reduce the number of processes for installation by incorporating a compact blocking filter for cutting off a power line carrier communication signal in a ground-fault interrupter. <P>SOLUTION: The ground-fault interrupter 1 comprises a low pass filter (blocking filter) 2 incorporated in the ground-fault interrupter 1, a leakage detector 3, an extractor 4, a power supply 5, a zero-phase converter 6, and a contact 7. The ground-fault interrupter 1 works as an ordinary ground-fault interrupter for the leakage of a power line, and it also blocks a power line carrier communication signal carried on a power line. The low pass filter 2 incorporated in the ground-fault interrupter 1 has a characteristic of blocking a power line carrier communication signal (frequency of 2-30 MHz) but not attenuating a current of a commercial power frequency (50 Hz or 60 Hz). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a leakage breaker for installation on a commercial power line in power line carrier communication.

  Power line carrier communication has been developed that superimposes a high frequency signal of 2 MHz to 30 MHz on a commercial power source to control communications and electronic devices, and revision of the legal system for introduction is under consideration. When power line carrier communication is introduced, there is a concern that power line carrier communication signals interfere with each other and the communication speed deteriorates between consumers who share power equipment such as pole transformers. Furthermore, since a communication signal leaks from the building to the power supply side (outdoors), there is a possibility of information leakage.

  As a method for avoiding these possibilities, there is an application of a blocking filter (a filter that blocks a power line carrier communication signal transmitted between commercial power supply conductors) (see Patent Document 1).

In addition, measures are taken to incorporate a low-pass filter in the earth leakage breaker so that the earth leakage breaker does not malfunction by detecting high-frequency current in the commercial power supply (see Patent Documents 2 and 3).
JP-A-5-22198 Japanese Patent No. 3454445 Japanese Patent Laid-Open No. 11-187466

  However, a coil or a core is used in the blocking filter according to the prior art, and the conductor becomes thicker according to the rated current capacity, the coil becomes larger, and the core becomes larger in order to prevent deterioration of characteristics due to magnetic saturation. For this reason, in the case of a general household, it is difficult to install a large coil in the distribution board, and the filter installation work has become large.

  Further, in the conventional earth leakage circuit breaker, since a filter is applied to the current detected by the zero-phase AC circuit, it is difficult to block the high frequency signal transmitted through the main circuit.

  The present invention has been made in view of the above problems, and its object is to incorporate a small blocking filter for cutting off power line carrier communication signals into an earth leakage breaker and to apply it to a distribution board in a general household. It is to make it easier and reduce the installation process.

  In order to solve the problem, the present invention according to claim 1 is a leakage breaker for cutting off a current when a current of a power line performing power line carrier communication by superimposing a high-frequency signal on the current is leaked, A low-pass filter is provided for transmitting a low-frequency commercial power supply frequency included in a current flowing through the power line and blocking a high-frequency power line carrier communication signal used for the power line carrier communication.

  According to a second aspect of the present invention, in the first aspect, the low-pass filter includes a main circuit for transmitting the current including the commercial power frequency, and the power line connected in parallel to the main circuit. A bypass circuit for transmitting the carrier communication signal.

  According to a third aspect of the present invention, in the first or second aspect, the low-pass filter includes a time constant circuit including a combination of a coil, a capacitor, and a resistor.

  According to a fourth aspect of the present invention, in the second or third aspect, the bypass circuit is a capacitor for preventing the power line carrier communication signal from leaking between a plurality of conductors constituting the power line. It is connected.

  According to a fifth aspect of the present invention, in any one of the second to fourth aspects, the low-pass filter is configured such that the circuit impedance of the bypass circuit is higher than that of the commercial power supply frequency. Has a time constant lower than the circuit impedance.

  According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the bypass circuit includes an overvoltage protection element having an equivalent capacitance instead of the capacitor.

  According to a seventh aspect of the present invention, in any one of the third to sixth aspects, the time constant circuit has a current capacity of at least 2.5 times the maximum value of the current flowing through the power line. It has.

  According to the present invention, a small blocking filter for cutting off a power line carrier communication signal is built in an earth leakage breaker, so that it can be easily applied to a distribution board in a general household, and the number of installation work steps can be reduced. .

  FIG. 1: has shown the block diagram based on embodiment of an earth-leakage circuit breaker. In FIG. 1, a leakage breaker 1, a low-pass filter (blocking filter) 2 built in the leakage breaker 1, a leakage detection unit 3, a drawing device 4, a power supply 5, and a zero-phase alternator 6 , Contacts 7 are shown. Note that the contact 7 is connected to a power line drawn from the outside and serves as a power source side input. Further, the low-pass filter 2 is arranged at the power output of the earth leakage circuit breaker 1 and connected to the load side that receives power supply.

  In the embodiment of the earth leakage breaker 1 having such a configuration, a low pass filter 2 is built in the earth leakage breaker 1 installed on the power line in order to prevent an earth leakage accident. And it has the characteristics in the structure which interrupts | blocks the power line carrier communication signal propagated in a power line while it operate | moves as a normal leakage breaker 1 with respect to the leakage of a power line. For this reason, the built-in low-pass filter 2 has a characteristic that does not attenuate the current of the commercial power supply frequency (50 Hz and 60 Hz) and blocks the power line carrier communication signal (frequency 2 to 30 MHz).

  FIG. 2 shows a configuration diagram according to the embodiment of the earth leakage breaker. FIG. 2 shows a bypass circuit 10 and a main circuit 11 provided in the low-pass filter 2 constituting the leakage breaker 1 shown in FIG.

  In such a configuration, the low-pass filter 2 has a characteristic of not attenuating the current of the commercial power supply frequency (50 Hz and 60 Hz) and blocking the power line carrier communication signal (frequency 2 to 30 MHz). Is provided with a time constant circuit to constitute a low-pass filter for transmitting a commercial power frequency at a low frequency. On the other hand, the bypass circuit 10 is also provided with a time constant circuit to constitute a high cut filter that transmits a high-frequency power line carrier communication signal.

  FIG. 3: has shown the block diagram of an example of the low-pass filter based on embodiment of an earth-leakage circuit breaker. FIG. 3 shows a plurality of coils 13 constituting the main circuit 11, a coil 14 constituting the bypass circuit 10, a resistor 15, and a capacitor 16.

  A coil 13 is inserted in series in each of the conductors of the three power lines energizing the main circuit 11, and constitutes a filter for transmitting a current of a low frequency commercial power supply frequency.

  The conductors of the three power lines that are conducted to the bypass circuit 10 are connected and drawn out in parallel to the three conductors that are energized to the main circuit 11, respectively. Inside the bypass circuit 10, a coil 14 and a resistor 15 are inserted in series with each conductor, and a capacitor 16 is disposed between the conductors to conduct both. The combination of the coil 14, the resistor 15, and the capacitor 16 constitutes a filter that blocks high-frequency power line carrier communication signals without transmitting them.

  As described above, the low-pass filter 2 is configured in parallel with the main circuit 11 and the bypass circuit 10, thereby reducing the overall size of the low-pass filter 2.

  In particular, when the capacitor 16 is placed between the conductors to be conducted, a high-frequency signal forms a circuit that passes through the capacitor 16, and as a result is cut off without being output from the bypass circuit 10. Note that an overvoltage protection element having an equivalent capacitance may be applied instead of the capacitor 16, and for example, a varistor or the like is preferably used.

  FIG. 4: has shown the block diagram of the specific structural example of the bypass circuit and the main circuit based on embodiment of an earth-leakage circuit breaker. FIG. 4 shows a configuration example including a 1 μH coil 22 as the main circuit 21 and a 10 nH coil 23 and a 1Ω resistor 24 as the bypass circuit 20.

  FIG. 5 is a graph showing the frequency characteristics of the time constant circuit configured as shown in FIG. In FIG. 5, the frequency characteristic of the bypass circuit 20 (bypass circuit 10) is shown as a characteristic 26 represented by a solid line, and the frequency characteristic of the main circuit 21 (main circuit 11) is shown as a characteristic 25 represented by a broken line. From the characteristics shown in FIG. 5, it can be seen that the circuit impedance of the bypass circuit 20 is lower than the circuit impedance of the main circuit 21 in a frequency region higher than the commercial power supply frequency.

FIG. 6 shows a configuration diagram of another specific configuration example of the bypass circuit and the main circuit according to the embodiment of the leakage breaker. FIG. 6 shows a coil L ₁ 30, a resistor R ₁ 31, a coil L ₂ 32, a resistor R ₂ 33, and a capacitor C 34 for configuring the low-pass filter 2.

  In such a configuration, the main circuit of the low-pass filter 2 passes the commercial power supply frequency, and the impedance of the frequency 2 to 30 MHz is sufficiently higher than the bypass circuit to transmit the power line carrier communication signal to the bypass circuit. It has become. Conversely, the bypass circuit has a configuration in which the impedance of the commercial power supply frequency is sufficiently large compared to the main circuit, and the impedance in the frequency band of power line carrier communication is sufficiently small compared to the main circuit.

Furthermore, in order to obtain sufficient insertion loss characteristics in the frequency band of power line carrier communication, values of coils (inductance), capacitors, and resistors that constitute the bypass circuit are set. In FIG. 6, the value of the coil L ₁ 30 is 100 nH, and the value of the resistor R ₁ 31 is 0.001Ω. Further, the value of the coil L ₂ 32 is 10 nH, the value of the resistor R ₂ 33 is 1Ω, and the value of the capacitor C 34 is 2 μF.

The electrical specifications of the coil L ₁ 30, the resistor R ₁ 31, the coil L ₂ 32, the resistor R ₂ 33, and the capacitor C 34 are designed based on the current and voltage value flowing through the earth leakage breaker 1. The value is set with the expected safety factor in mind. As the safety factor, the electrical standard can be determined by a value such as 2.5 times the power to be handled. By considering such a safety factor, sufficient safety can be ensured when the earth leakage circuit breaker 1 is actually operated.

  FIG. 7 shows the result of measuring the insertion loss in the low-pass filter shown in FIG. As shown by the characteristic 40 in FIG. 7, there is almost no insertion loss at the commercial power supply frequency, and a sufficient loss of 40 dB or more is obtained in the frequency band of the power line carrier communication.

  For example, when an insertion loss characteristic equivalent to the characteristic shown in FIG. 7 is realized using a conventional technique, the inductance of the coil constituting the low-pass filter needs to be a large value of 10 μH or more. In addition, since a commercial power supply current of several tens of A is directly transmitted to the coil, when a core made of a magnetic material or the like is applied to the coil to be used, it is necessary to enlarge the core in order to prevent characteristic deterioration due to magnetic saturation. There is. On the other hand, when an air-core coil is used as the coil, it is necessary to increase the number of turns of the coil in order to increase the inductance value.

  That is, according to the present embodiment, the low-pass filter can be easily built in the leakage breaker without increasing the size of the low-pass filter, and sufficient loss characteristics can be exhibited for the power line carrier communication signal. .

  Furthermore, since the earth leakage circuit breaker incorporating the small low-pass filter can be realized, the installation work does not become large and can be easily installed.

The block diagram based on embodiment of an earth-leakage circuit breaker is shown. The block diagram based on embodiment of an earth-leakage circuit breaker is shown. The block diagram of an example of the low-pass filter based on embodiment of an earth-leakage circuit breaker is shown. The block diagram of the specific structural example of the bypass circuit and the main circuit which concerns on embodiment of an earth-leakage circuit breaker is shown. The frequency characteristics of the time constant circuit configured as shown in FIG. 4 are shown in a graph. The block diagram of the concrete another structural example of the bypass circuit and the main circuit based on embodiment of an earth-leakage circuit breaker is shown. The graph of the result of having measured the insertion loss in the low-pass filter shown in FIG. 6 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Leakage circuit breaker 2 Low-pass filter 3 Leakage detection rod 4 Pull-out device 5 Power supply 6 Zero-phase AC 7 Contact 10 Low-pass filter 11 Main circuit

Claims (7)

In the leakage breaker for cutting off the current when the current of the power line performing power line carrier communication by superimposing the high frequency signal on the current leaks,
An earth leakage circuit breaker comprising a low-pass filter for transmitting a low-frequency commercial power supply frequency included in a current flowing through the power line and blocking a high-frequency power line carrier communication signal used for the power line carrier communication. The low-pass filter is
A main circuit for transmitting the current including the commercial power supply frequency;
A bypass circuit connected in parallel to the main circuit for transmitting the power line carrier communication signal;
The earth-leakage circuit breaker of Claim 1 characterized by the above-mentioned. The low-pass filter is
3. The earth leakage breaker according to claim 1, wherein the circuit breaker is constituted by a time constant circuit including a combination of a coil, a capacitor, and a resistor. The bypass circuit is:
The earth leakage circuit breaker according to claim 2 or 3, wherein a plurality of conductors constituting the power line are connected by a capacitor for preventing the power line carrier communication signal from leaking. The low-pass filter is
5. The earth leakage circuit breaker according to claim 2, wherein the circuit impedance of the bypass circuit has a time constant lower than the circuit impedance of the main circuit in a frequency region higher than the commercial power supply frequency. . The bypass circuit is:
The earth leakage circuit breaker according to any one of claims 2 to 5, further comprising an overvoltage protection element having an equivalent capacitance instead of the capacitor. The time constant circuit is:
The earth leakage circuit breaker according to any one of claims 3 to 6, further comprising a current capacity of at least 2.5 times the maximum value of the current flowing through the power line.

Images