JPH1098828A - Leak protection system and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a measure for high frequency element for human body protection in a leak protection system combining a high speed, high sensitivity earth leakage breaker and a medium/low sensitivity time delay earth leakage breaker. SOLUTION: In a leak protection system comprising a first leak detecting means formed to be connected to a load and a second leak detecting means provided in the higher stage of the first leak detecting means, the first leak detecting means is provided with a first means to give the sensitivity current frequency characteristic which takes a value of 30mA for the commercial power supply frequency, a value between 30mA and 100mA for 100Hz, a value between 100mA and 1000Am for 1kHz and a value less than the characteristic of threshold value for human body protection increasing depending on the frequency between 100Hz to 1kHz and the second leak detecting means is provided with a second means to give the sensitivity current frequency characteristic which makes the sensitivity current frequency characteristic larger than the characteristic of the first leak detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage protection system and, more particularly, to an earth leakage protection system and an earth leakage protection device constituting the system, which are suitable for interrupting the earth leakage at a frequency exceeding the commercial frequency by protecting and coordinating. .

[0002]

2. Description of the Related Art In a conventional earth leakage protection system, when cascading earth leakage circuit breakers to achieve protection coordination, the system has been configured with only the sensitivity current and operation time as problems. As an example, consider a system as shown in FIG. In this system, a medium-sensitivity time-delay type earth leakage breaker ELB101 (sensitivity current 500 m
A, the operation time is 1.2 seconds, and on the lower side, the earth leakage breaker ELB102 (sensitivity current 200 mA, operation time 0.
3 seconds) are connected in cascade, and this earth leakage breaker ELB10
2, in the illustrated example, two high-speed and high-sensitivity type earth leakage breakers E
LB103 and ELB104 are connected in parallel. And
As shown in FIG. 12, the electric motor IM2 is connected to the electric circuit provided with the earth leakage breaker ELB103, and the earth leakage breaker ELB1 is connected.
It is assumed that the electric motor IM1 is connected to the electric circuit provided with 04. FIG. 13 shows the operation characteristics of the earth leakage breakers ELB101 to ELB103. In this earth leakage protection system, for example, when a ground fault occurs in the electric motor IM2, the earth leakage breaker ELB103 detects this and functions to cut off this electric circuit.

FIG. 14 shows a high-speed and high-sensitivity earth leakage breaker ELB.
FIG. 15 is a main part configuration diagram of a leakage detector in FIG.
FIG. 4 is a waveform diagram of each part of the leakage detector. FIG.
A portion surrounded by a dashed line is a portion formed by a monolithic IC. A secondary-side output current of a zero-phase current transformer (hereinafter, referred to as ZCT) 2 provided on an electric circuit to be subjected to leakage detection is converted into a voltage VLK by a resistor 3. This voltage VLK is amplified by an amplifier in IC1, and then compared with a reference voltage AVT (DC) by a comparator in IC1. From this comparator, when VLk ≧ AVT (DC), the constant current IO
D is output, and the capacitor 5 is charged with the constant current IOD. If VLK ≧ AVT (DC) is short,
Although the charging period of the capacitor 5 is short, the capacitor 5 is discharged before its terminal voltage VOD reaches a specified value, but VLk ≧ AVT (DC)
Is long, the charging of the capacitor 5 proceeds, the terminal voltage VOD reaches the specified value, becomes higher than the trigger potential of the latch circuit, and the thyristor 8
Is driven to open an open / close contact (not shown) and cut off the electric circuit.

FIG. 16 is a configuration diagram of a main part of an electric leakage detector in the intermediate-sensitivity extended-type earth leakage breaker ELB102 shown in FIG. The internal circuit of IC1 is the same as that of FIG. The secondary-side output current of ZCT2 provided on the electric circuit to be detected as a leakage is subjected to current / voltage conversion by the resistor 3 and is passed through the low-pass filter formed by the resistor 4 and the capacitor 10 to obtain an IC.
1 is input to the amplifier. And
The signal output from the comparator to the "4" pin charges the capacitor 12 via the diode 11 connected in the forward direction. When the terminal voltage of the capacitor 12 reaches a predetermined value, the signal is output via the time delay circuit 17. A shutoff signal is output to the circuit 18.

[0005] The earth leakage protection system shown in FIG. 12 is intended for a commercial frequency, and does not consider any higher frequency. However, in recent years, electric devices such as air conditioners driven by inverters have increased,
As a result, the frequency of the leakage current may be higher than the commercial frequency. For example, as shown in FIG. 12, when an electric motor IM2 is driven by the inverter INV and a ground fault occurs, a high-frequency leakage current of, for example, 20 kHz flows through this electric circuit. When the leakage current of 20 kHz flows, the leakage detector shown in FIG.
Since the cycle of the charging current for charging 4) is shortened, the terminal voltage VOD of the capacitor 5 does not reach the specified value for interrupting the leakage. That is, as shown in FIG. 17, the sensitivity current frequency characteristic of the conventional high-speed earth leakage circuit breaker ELB103 is as follows.
When the frequency reaches a certain value exceeding the commercial frequency, the characteristic has a sharp rising characteristic. For this reason, even if a high-frequency leakage current flows, this circuit is connected to a conventional high-speed leakage breaker ELB103.
Is no longer blocked, for example, by the International Electrotechnical Commission (Intern
ational Electrotechnical Commission, IEC
That. ) Leakage current equal to or greater than the threshold value indicated by 479-2 flows, which is dangerous.

[0006] On the other hand, in the middle-sensitivity extended-type earth leakage breaker shown in FIG. 16, the secondary output current of the ZCT 2 is subjected to current / voltage conversion by the resistor 3, and is passed through a low-pass filter formed by the resistor 4 and the capacitor 10. It is configured to input to the differential amplifier of IC1. For this reason, when the input frequency increases, the input signal to the differential amplifier decreases, and the output of the differential amplifier also decreases.Therefore, if the frequency increases, the leakage current will not be detected unless a large leakage current flows. Would. In other words, the sensitivity current frequency characteristic of the intermediate-sensitivity earth leakage circuit breaker can be considered that the sensitivity current substantially increases as the input frequency increases. However, as shown in FIG. 17, the method of increasing the sensitivity current does not show a steep rising like a high-speed type, but rises gently.

For this reason, in the leakage protection system shown in FIG. 12, when a leakage current of, for example, 20 kHz flows through the motor IM2, the frequency characteristics of the high-speed leakage breaker ELB103 and the medium-sensitivity leakage breaker ELB102 are shown in FIG. Therefore, the high-speed earth leakage breaker ELB103 cannot detect this, and the middle-sensitivity earth leakage breaker ELB102 cuts off the electric circuit. For this reason, even the motor IM1 that does not need to be stopped will stop.
That is, there is a problem that protection coordination cannot be performed in a region exceeding the commercial frequency.

Japanese Unexamined Patent Publication No. Sho 61-1986 relates to an earth leakage circuit breaker which operates so that a surge or noise which is not an earth leakage current is judged as an earth leakage current so as not to cut off an electric circuit.
161921 and JP-A-61-154422.
Another related art is disclosed in Japanese Patent Application Laid-Open No. 61-12 / 1986.
No. 8719 is disclosed. In this prior art,
Generates a pulse train with a pulse width of a fixed ratio to the voltage or current cycle of the circuit, compares this pulse train with the output of the leakage detection circuit, and cuts off the circuit when the output of the leakage detection circuit is larger than the pulse train doing.

[0009]

As described above, the conventional leakage protection system does not take measures to prevent malfunction due to leakage current having a high frequency. JP-A-61-1
The prior art described in Japanese Patent Application Laid-Open No. 61921/1986 and Japanese Patent Application Laid-Open No. 61-154422 simply determines that a sporadic or non-periodic surge or noise flows through an electric circuit and determines that this is a leakage current and cuts off the electric circuit. They just take measures to prevent them from happening. In the prior art described in Japanese Patent Application Laid-Open No. 61-128719, the operable frequency changes in accordance with a change in the frequency of the electric circuit. However, there is a problem that protection coordination cannot be taken.

[0010] An object of the present invention is to enable protection coordination even when leakage current of a frequency exceeding the commercial frequency flows, and to cut off leakage current exceeding a threshold value set for the purpose of protecting the human body. An object of the present invention is to provide a leakage protection device that can prevent operation and is excellent in safety and a leakage protection system using the same.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric leakage protection device, comprising: an electric leakage current detecting means; a frequency characteristic setting means connected to the electric leakage current detecting means for setting a sensitivity current characteristic with respect to a frequency; Output means connected to the means, the sensitivity current characteristic is 30 mA at commercial frequency
At 100Hz, take a value between 30mA and 100mA and take 1KHz
In the range between 100mA and 1000mA, the characteristic increases with increasing frequency between 100Hz and 1kHz, and increases with increasing frequency between 100Hz and 1kHz in relation to the characteristic of the threshold for human body protection. Is achieved by setting

Further, the above object is provided with a first leakage detecting means configured to be connected to a load, and a second leakage detecting means provided above the first leakage detecting means. In the leakage protection system, the first leakage detection means has first means for giving a characteristic in which the sensitivity current frequency characteristic changes at a value below a threshold having a predetermined current frequency characteristic determined for the purpose of protecting the human body, The second leakage detecting means is achieved by having the second means for providing a characteristic in which the sensitivity current frequency characteristic has a value larger than the characteristic of the first leakage detecting means.

[0013]

The leakage protection device includes leakage current detection means, frequency characteristic setting means connected to the leakage current detection means for setting a sensitivity current characteristic with respect to frequency, and output means connected to the frequency characteristic setting means. The sensitivity current characteristic takes a value of 30 mA at commercial frequency, takes a value between 30 mA and 100 mA at 100 Hz, takes a value between 100 mA and 1000 mA at 1 KHz, and takes 100 Hz
In relation to the characteristics of the threshold value for human body protection that increases with an increase in frequency between 1 and 1 kHz, it is set to a characteristic that increases with an increase in frequency between 100 Hz and 1 kHz. Even when a leakage current flows, the leakage protection device can cut off the electric circuit. Further, since the above characteristics are determined in relation to the characteristics of the threshold value of IEC479-2, it is possible to improve safety with respect to human body protection. Further, since the above-described leakage protection device operates at a low leakage current value, it can be used as a high-speed and high-sensitivity leakage protection device.

Further, in a leakage protection system comprising first leakage detection means configured to be connected to a load, and second leakage detection means provided above the first leakage detection means. The first leakage detecting means has a first means for giving a characteristic in which the sensitivity current frequency characteristic changes at a value lower than a threshold having a predetermined current frequency characteristic determined for the purpose of protecting the human body, and the second means. Since the leakage detecting means has the second means for giving the characteristic that the sensitivity current frequency characteristic has a value larger than the characteristic of the first leakage detecting means, if the leakage current having a frequency higher than the commercial frequency flows, The first leakage detecting means cuts off the corresponding electric circuit because the leakage current value exceeds the sensitivity current value, and the second leakage detection means connected to the upper level does not allow the leakage current value to reach the sensitivity current value. The electric circuit is high It does not block the wave of current leakage. For this reason, a leakage current dangerous to a human body exceeding the threshold of IEC479-2 is cut off, and since the protection coordination is taken, this ground fault accident does not spread to other people.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an earth leakage protection system according to a first embodiment of the present invention. In this embodiment, an earth leakage breaker having a contact for shutting off or opening an electric circuit is used as an earth leakage protection device. However, the present invention is not limited to this, and an earth leakage detector capable of generating an output for interrupting an electric circuit is used. It may be a vessel. A high-speed, high-sensitivity type leakage breaker ELB3 as first leakage detection means is mounted on the electric circuit of the motor IM2 driven by the inverter INV,
-Sensitivity extended-type earth leakage breaker ELB as leakage detection means
2, the protection coordination is performed, and a medium-sensitivity extended leakage breaker ELB1 that performs protection coordination with the medium-sensitivity extended leakage breaker ELB2 is further mounted thereon.

In this embodiment, a high-speed and high-sensitivity earth leakage breaker E
The sensitivity current frequency characteristic of LB3 is such that the sensitivity current is flat up to about 75 Hz and increases with a substantially constant slope above this as shown by the curve I in FIG. That is, as shown in FIG. 2, the sensitivity current characteristic is 30 at the commercial frequency.
Take the value of mA and at 100Hz take the value between 30mA and 100mA and 1K
In Hz it takes values between 100 mA and 1000 mA and increases with increasing frequency between 100 Hz and 1 kHz, increasing with increasing frequency between 100 Hz and 1 kHz in relation to the characteristics of the threshold for personal protection Set to properties. Further, as shown by a curve II, the sensitivity current frequency characteristic of the medium-sensitivity rolled-type earth leakage circuit breaker ELB2 has a flat value and a value larger than the curve I up to a sensitivity current of about 90 Hz, and a substantially constant slope when the sensitivity current exceeds this. , And rises sharply at about 150 Hz.
Further, as shown by a curve III, the sensitivity current frequency characteristic of the
Up to z, it is flat and takes a value larger than the curve II, and when it exceeds this, it has a characteristic that it rises sharply at about 120 Hz.

A threshold value determined by a change based on the 50/60 Hz of the ventricular fibrillation limit value described in IEC479-2 described above (“Perception threshold” described in “Effect of human body passing current” or “Ventricular fibrillation”) The solid line X in FIG. 2 is obtained by converting the dynamic threshold value) into a rated sensitivity current of 30 mA using the frequency-frequency coefficient relationship shown in FIG. That is, the curve I
Are set to be lower than the solid line X and parallel to the solid line X in the entire frequency range, and the curves II and III are characteristics that rise sharply at frequencies exceeding the commercial frequency. The curve III rises closer to the commercial frequency than the curve II.

FIG. 4 is a main part configuration diagram of a leakage detector used in the high-speed and high-sensitivity leakage breaker ELB3 according to the present embodiment. The internal configuration of the IC 1 is the same as that shown in FIG. 14 and internally includes an amplifier, a comparator, a latch circuit, a constant voltage circuit, and a current source, and the positive input side of the amplifier is connected to the power supply VBIAS via a resistor. The negative side is connected to the input terminal "2" pin. The power supply VBIAS is connected to an output terminal "1" pin, and is connected to an external Z
Supply current to CT2. The output of the amplifier is connected to the positive (non-inverting) input of the comparator. The minus (inverting) input of the comparator is connected to a reference voltage AVT (DC). The output of the comparator controls the current source connected to it, and its output is output to pin "4". The input of the latch circuit is connected to the “5” pin, and the non-inverted output is output to the “6” and “7” pins. The output of the latch circuit is output as it is to the “6” pin, and is output via the current source to the “7” pin. The power supply voltage VCC is supplied from the constant voltage circuit to the amplifier, the comparator, the latch circuit, and the current source, and each ground side is connected to the ground side output of the constant voltage circuit. In the constant voltage circuit, the input side is connected to the "8" pin and the power supply voltage VCC
Is supplied, and the output on the ground side is output to the “3” pin.

In this embodiment, the IC 1 and the IC 1
, A low-pass filter including a resistor 4 and a capacitor 10 connected to the “1” and “2” pins, and a diode 11, a capacitor 12, and a resistor 1 connected to the “4” pin of the IC 1.
The circuit including the zener diode 14, the resistor 15, and the comparator 16 constitutes a first frequency characteristic applying unit 70.

In a conventional high-speed and high-sensitivity type earth leakage breaker, ZC
Although the secondary output current of T2 is converted to voltage only by the resistor 3, in the present embodiment, the secondary output current of ZCT2 is converted from current to voltage by the resistor 3, and is formed by the resistor 4 and the capacitor 10. "1" of IC1 through a low-pass filter
Input to "2" pin. For this reason, when the frequency of the leakage current increases, the difference between the two input signals decreases, and the leakage is not detected unless the leakage current value increases. The voltage VLK converted by the resistor 3 is amplified by the amplifier in the IC1, and then the reference voltage AVT is calculated by the comparator in the IC1.
(DC). From this comparator, VLk ≧ A
At VT (DC), a constant current is output, and the capacitor 12 is charged with this constant current. The terminal voltage of the capacitor 12 and the reference voltage are compared by a comparator 16 external to the IC 1, and when the terminal voltage of the capacitor 12 exceeds the reference voltage, a leakage detection signal is output to the output circuit 18 by the comparator 16.
Is output from At this time, the output of the “4” pin is applied to the capacitor 12 via the forward diode 11.
The discharge from the capacitor 12 to the “4” pin side is prevented by the diode 11, and when a leakage current exceeding a threshold value flows in a high frequency range exceeding the commercial frequency, the reference voltage of the comparator 16 is reliably increased. Can be exceeded. Thereby, the characteristic of the curve I in FIG. 2 is realized.

FIG. 5 is a main part configuration diagram of an earth leakage detector used in the middle-sensitivity extension earth leakage breaker ELB2 according to the present embodiment. The internal configuration of each of the ICs 1a and 1b is the same as that of the IC 1, and illustrations other than those required for the following description are omitted. In this embodiment, the medium-sensitivity delay type earth leakage circuit breaker uses two ICs in order to make the sensitivity current frequency characteristics shown by curves II and III in FIG.
To obtain the characteristics of the medium sensitivity extended type, and obtain the characteristics of the high speed and high sensitivity type by the other IC 1b. The secondary-side output current of the ZCT 2 attached to the electric circuit to be detected is subjected to current / voltage conversion by the resistor 3, and the “1” of each of the ICs 1 a and 1 b is passed through a low-pass filter formed by the resistor 4 and the capacitor 10. , "2" pins.

In this embodiment, a low-pass filter circuit comprising a capacitor 10 and a resistor 4 connected to the "1" and "2" pins of the ICs 1a and 1b, and the ICs 1a and 1b
The circuit extending from C1b to the time delay circuit 17 and the time delay circuit 17 constitute the second frequency characteristic imparting means 72. IC
1a, the forward diode 1
1, the capacitor 12 is charged. The terminal voltage of the capacitor 12 is
Through the output circuit 18.
In the IC 1b, the capacitor 5a is output with the "4" pin output.
Is charged. In the present embodiment, the capacitor 5a is connected to the capacitor 5b or the capacitor 5b.
c are connected in parallel by a characteristic changeover switch 26. The terminal voltage of this capacitor 5a is IC
1b is connected to the "5" pin. The output of the inverter 21 is connected to this "5" pin via a resistor.
b, a forward diode 20 is connected between the “7” pin and the input of the inverter 21. The input of the inverter 21 and the terminal voltage of the capacitor 12 are connected via the buffer 23 and the resistor 24. A resistor 22 is inserted between the input of the inverter and the ground, and the inverter 2
The reference potential VCC is connected to the input 1 via the switch 25.

Next, the operation of the leakage detector of the intermediate-sensitivity delay type circuit breaker ELB2 in this embodiment will be described with reference to the waveform diagram of FIG. Inverters are connected to the lower level,
If there is a risk of leakage current having a frequency exceeding the commercial frequency, the switch 25 is disconnected from VCC. As a result, the terminal voltage of the capacitor 12 depends on the output of the “7” pin of ICIb. Now, ZCT2 detects the leakage current of the commercial frequency, and IC1
a, a signal is input to the IC 1b. When the capacitor 5a is charged by the output of the "4" pin of the IC 1b and the terminal voltage reaches a predetermined value (this terminal voltage waveform is indicated by the symbol A in FIG. 6), the terminal voltage is latched by the latch circuit, and " A predetermined voltage is output from the 7 ″ pin. This "7"
In response to the pin output, the inverter 21 discharges the capacitor 5a and resets the “7” pin output. This "7" pin output waveform is indicated by reference numeral B in FIG. The output of the "7" pin is applied to the terminal of the capacitor 12 via the buffer 23 and the resistor 24, and functions to prevent the discharge of the capacitor 12. By setting the charging time constant of the capacitor 12 shorter than the discharging time constant, the terminal voltage of the capacitor 12 becomes
As shown by symbol C in FIG. 6, the voltage gradually increases, and when the terminal voltage of the capacitor 12 reaches a predetermined value, a cutoff signal is output to the output circuit 18 via the time delay circuit 17.

When a leakage current having a frequency exceeding the commercial frequency flows, the terminal voltage of the capacitor 12 gradually increases due to the output of the "4" pin of the IC 1a. That is, IC1
The sensitivity current frequency characteristic on the a side is such that the sensitivity current gradually rises as the frequency increases (see the characteristic indicated by the broken line in FIG. 17). On the other hand, the cycle of the output of the “4” pin of the IC 1b is shortened, and the charging time of the capacitor 5 is shortened.
The potential of the capacitor 5 does not rise, and the terminal voltage does not reach the next-stage latch circuit trigger potential. Therefore, the output of the “7” pin of the IC 1b remains at the low level, and the buffer 2
3 is synced. Therefore, the discharge current from the capacitor 12 escapes through the route of the resistor 24 and the buffer 23, and the time delay circuit 17 and the output circuit 18 at the next stage do not operate. As a result, the earth leakage breaker ELB2 stops operating in the frequency range exceeding the commercial frequency, and the sensitivity current becomes infinite. Therefore, the sensitivity current frequency characteristic of the whole circuit shown in FIG. As shown, it rises steeply. Here, the switch 26 is switched, and IC1
By changing the capacity of the capacitor charged by the "4" pin output of b, it is possible to determine the change of the cutoff frequency, that is, the characteristic of the curve II or the curve III. That is, the earth leakage breaker of the present embodiment can be used as a medium-sensitivity extended earth leakage breaker by switching the switch 26. By providing this switch 26, the characteristics of the earth leakage breaker and the like can be adjusted or switched, and an earth leakage protection system tailored to the purpose can be assembled. After the switch 26 is assembled with the earth leakage protection system, the user may not be able to change the switch without permission, for example, by brazing.
Further, the switch 26 may be configured to operate in conjunction with a sensitivity current switch and an operation time switch (not shown) so that various characteristics of the earth leakage breaker may be simultaneously switched.

In this embodiment, a medium-sensitivity extended-type earth leakage breaker ELB
In the case of No.2, when there is no load in which a leakage current of a frequency exceeding the commercial frequency flows, the same function as that of the conventional medium-sensitivity time delay type is sufficient. That is, when the same function as the conventional one is used, the switch 25 is connected to the potential VCC. As a result, the input side of the buffer 23 is always at the high level, and the terminal voltage of the capacitor 12 becomes independent of the output of the "7" pin of the IC 1b. That is, by connecting the switch 25 to the VCC side, the circuit of FIG. 5 has substantially the same characteristics as the conventional medium-sensitivity extended type (see FIG. 16).

The earth leakage breaker that can be used in the earth leakage protection system of the present invention is not limited to the above embodiment.
Another embodiment of the medium-sensitivity rolling type earth leakage breaker and the high-sensitivity high-speed earth leakage breaker will be described with reference to FIGS.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a main part configuration diagram of an earth leakage detector used for a medium-sensitivity extended earth leakage breaker according to a second embodiment of the present invention,
The internal configuration of IC1 is the same as that of FIG. Also, FIG.
FIG. 8 is a waveform chart of each part of the circuit shown in FIG. 7. In this embodiment,
IC1; a low-pass filter including a capacitor 10 and a resistor 4 connected to the "1" and "2" pins of IC1;
The circuit extending from the capacitor 5 connected to the "4" pin of C1 to the time delay circuit 17 and the time delay circuit 17 serve as the second frequency characteristic applying means 74. When the leakage current of the commercial frequency is detected by the ZCT2, there is a "4" pin output when the difference between the input signals of the "1" pin and the "2" pin of the IC1 exceeds a predetermined value. When the capacitor 5a is charged by the output of the "4" pin and the terminal voltage B of the capacitor 5a exceeds the reference value A, the comparator 33 outputs an output of a predetermined potential. The one-shot multi-circuit 34 operates by the output pulse C of the comparator 33, and the pulse signal D is output from the circuit 34. The pulse signal D charges the capacitor 36 through the forward diode 35. When the terminal voltage E of the capacitor 36 exceeds the reference potential F set by Vcc, the resistor 38 and the Zener diode 39, the comparator 40 outputs a predetermined potential. The signal G is output to the time delay circuit 17, and the signal H delayed by a predetermined time in the time delay circuit 17 is output to the output circuit 18. Therefore, the corresponding electric circuit can be interrupted by the leakage current at the commercial frequency.

When the leakage current exceeding the commercial frequency is detected by the ZCT2, the output of the "4" pin of the IC1 becomes small, and the charging of the capacitor 5a does not proceed until the reference value A of the comparator 33 is reached. Therefore, the intermediate-sensitivity extended earth leakage breaker does not cut off at a high frequency input. By selecting the capacitors 5b and 5c connected in parallel with the capacitor 5a by the switch 26 as in the embodiment of FIG. 5, the frequency at which the reference value A of the comparator 33 is not reached can be selected. Can be. As described above, the high-speed and high-sensitivity type earth leakage breaker shown in FIG.
A commercial leakage protection system is configured by combining with a leakage detector of the medium-sensitivity type (the embodiment is described as a time-delayed type, but the time limit type may be used) as shown in FIG. 5 or FIG. Protection against leakage current at a frequency and protection against leakage current at a frequency exceeding the commercial frequency can be achieved.

A third embodiment of the present invention will be described with reference to FIGS. The sensitivity current frequency characteristic of the high-sensitivity high-speed leakage detector is preferably a characteristic below a threshold value of ventricular fibrillation described in IEC479-2. However, this ICE479-2
Describes only the threshold of ventricular fibrillation up to 1 kHz. For frequencies above 1 kHz, the following is preferred. FIG. 9 is a diagram illustrating characteristics of the earth leakage breaker exceeding 1 kHz. A represents the sensitivity current frequency characteristic of the middle / low-sensitivity extension type earth leakage breaker, and B represents the sensitivity current frequency characteristic of the high-speed high sensitivity earth leakage breaker. Here, the characteristic C is a threshold characteristic of ventricular fibrillation described in IEC479-2, the characteristic D is a threshold characteristic of perception described in IEC-2, and the characteristic E is a threshold characteristic of energization described in IEC479-2. The characteristic A of the medium-to-low-sensitivity extended-type earth leakage circuit breaker has a characteristic that, like the above-described embodiment, rises sharply at a frequency slightly higher than the commercial frequency (50/60 Hz) (110 Hz in the illustrated example). The characteristic B of the high-speed and high-sensitivity earth leakage breaker is changed substantially in parallel with the characteristic C at a value lower than the characteristic C between the commercial frequency and 1 kHz, and
Between 10 kHz, it is changed almost parallel to the characteristic D,
At a frequency exceeding 10 kHz, the characteristic changes substantially parallel to a curve obtained by extrapolating the characteristic D. The high-speed and high-sensitivity leakage detector according to the above-described embodiment is an embodiment satisfying the characteristic B. However, since the circuit is configured only to satisfy the required characteristics, the number of circuit components increases, and there is an inconvenience in downsizing. Therefore, an embodiment for miniaturization will be described below.

FIG. 10 is a block diagram of a high-speed and high-sensitivity type leakage detector which is miniaturized. The first frequency assigning means 76 in the present embodiment includes IC1 and “1” of IC1,
A low-pass filter connected to the “2” pin,
It is composed of a circuit up to the output circuit 18. FIG.
Elements and functions that are the same as those of the embodiment shown in FIG. As in the other embodiments, ZCT2 is connected to the "1" and "2" pins of the IC1, and its output is amplified by the IC built-in amplifier and output to the "4" pin. The output of “4” is supplied to a parallel circuit of a capacitor 12 and a resistor 13 via a diode 11. In addition, C2
Is a capacitor for preventing malfunction. The cathode connection point between the capacitor 12 and the diode 11 is connected to the “5” pin of IC1. The “7” pin of IC1 is the output circuit 1
8 is connected. The capacitor C3 between the "7" pin and the "6" pin is a capacitor for preventing malfunction of the IC1.
The power supply voltage V is stabilized by the Zener diodes ZD1 and ZD2, further divided by the Zener diode ZD2, and supplied to the pin 8 with the power supply voltage VCC. In the present embodiment, since the power supplies of the IC1 and the trip unit (only the coil 50 of the trip device is shown) are different, the power supplies are stabilized by the Zener diodes ZD1 and ZD2, respectively. The capacitors 7 and C1 are capacitors for stabilizing the power supply. The anode of the thyristor 8 is connected to a coil 50 of a circuit breaker trip device (not shown).
Is connected to the power supply voltage V. The gate of the thyristor 8 is connected to the “7” pin of the IC 1 and to the capacitor 6 for preventing malfunction.

Next, the operation of this embodiment will be described. When ZCT2 detects the leakage current, "4" of IC1
The current IOD shown in FIG.
The potential of the thyristor 8 changes as shown by C in FIG. 6 and when this potential becomes equal to or higher than the voltage VTRf in FIG. 15, the gate trigger current of the thyristor 8 is output from the "7" pin of IC1, and the trip unit operates. The operation according to the frequency change is the same as that of the embodiment of FIG. 4, and the threshold value of the comparator 16 obtained by the Zener diode 14 shown in FIG.
It is given by VTRf of 1. According to the present embodiment, since only the integrated circuit element and the leakage detection IC 1 are used, the circuit supply current is small, so that the load on the power supply circuit (not shown) can be reduced. In addition, the number of components is reduced, and only small components need to be used.

Next, a description will be given of an embodiment of a small / medium / low-sensitivity time-delay type earth leakage breaker which is reduced in size with reference to FIG. The second frequency characteristic applying means 78 in the present embodiment is an IC
1, a low-pass filter connected to the “1” and “2” pins of the IC 1, a circuit extending from the IC 1 to the time delay circuit 17, and the time delay circuit 17. Elements and functions that are the same as those of the previously described embodiment are given the same reference numerals, and description thereof is omitted. As in the other embodiments, ZCT2 is connected to the "1" and "2" pins of IC1, and its output is amplified by an IC built-in amplifier and output to "4" pin. C2
Is a capacitor for preventing malfunction. The output of the "4" pin is supplied to the capacitor 5 and is output via the "5" pin.
It is supplied to a latch circuit built in C. The capacitor C3 connected to the "6" pin is a capacitor for preventing malfunction of the IC1. The “7” pin of IC 1 is connected to the output circuit 18. The power supply voltage V is equal to the Zener diodes ZD1 and ZD2.
And the voltage is further divided by the Zener diode ZD2, and the power supply voltage VCC is supplied to the "8" pin. In the present embodiment, since the power supply voltages of the IC1 and the coil 50 of the trip unit are different, the power supplies are stabilized by the Zener diodes ZD1 and ZD2, respectively. I
The time delay circuit 17 is connected to the “7” pin of C 1, and the output of the time delay circuit 17 is connected to the gate of the thyristor 8. Next, a detailed configuration of the time delay circuit 17 will be described. The “7” pin of the IC 1 is connected to the anode of a Zener diode 72 whose cathode is connected to the circuit ground and one end of a resistor group 71 provided in parallel.
The other end of the resistor group 71 is connected directly or via the switch 26 to a parallel circuit of a capacitor 75 and a resistor 73,
Connected to the gate of T74. The drain terminal of this FET 74 is connected to the “7” pin of IC1, and the source terminal is
It is connected to the gate of thyristor 8. Capacitor 6
Is for preventing malfunction of the thyristor 8. Next, the operation of the earth leakage breaker according to the present embodiment will be described. When the leakage is detected, there is a constant current output IOS from the "7" pin of IC1. This current output IOS is based on the Zener diode 72 and the resistor group 7.
1 and the potential of the capacitor 75 rises. The rise of the potential of the capacitor 75 causes the next-stage FET 74 to conduct, and the gate of the thyristor 8 is triggered. As a result, the coil 50 is energized, and the trip unit operates.

According to the present embodiment, since only the leakage detection IC 1 is used as an integrated circuit element, the thyristor gate trigger current of the time delay circuit drive and output circuit is controlled by the IC 1.
, The power supplied to the circuit is small, and the burden on a power supply circuit (not shown) is reduced. Furthermore, since the number of components is small and only small components can be used, the load on the power supply can be reduced and the size of the entire apparatus can be reduced.

In the above-described embodiment, a high-speed earth leakage breaker with a medium / low sensitivity has not been described. However, when such an earth leakage breaker (earth leakage relay, earth leakage detector) is used, FIG. By making the characteristics parallel or substantially parallel to the threshold characteristics X as in the characteristics shown by the curves V and IV, it is possible to take protection coordination and cut off the leakage current exceeding the commercial frequency.

[0035]

According to the present invention, even when a leakage current having a frequency exceeding the commercial frequency flows, protection coordination can be performed and a leakage current equal to or greater than a threshold value set for the purpose of protecting the human body can be cut off. In addition, it is possible to obtain an earth leakage protection device which can prevent annoying operation and is excellent in safety and an earth leakage protection system using the same.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an earth leakage protection system according to a first embodiment of the present invention.

FIG. 2 is a ground fault protection device (ground fault relay, ground fault detector) used in the ground fault protection system according to the first embodiment of the present invention.
6 is a sensitivity current frequency characteristic diagram of FIG.

FIG. 3 is a characteristic diagram showing a frequency-frequency coefficient relationship of a threshold value for protecting a human body from electric leakage.

FIG. 4 is a circuit diagram showing a main configuration of a leakage detector used in a high-speed and high-sensitivity leakage breaker of the leakage protection system according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a main part of an electric leakage detector used for a medium-sensitivity extended-type earth leakage breaker according to the first embodiment of the present invention.

FIG. 6 is a waveform diagram of each part of the circuit shown in FIG. 5 of the earth leakage protection system according to the first embodiment of the present invention.

FIG. 7 is a circuit diagram showing a configuration of a main part of an electric leakage detector used for a medium-sensitivity extended-type earth leakage breaker according to a second embodiment of the present invention.

FIG. 8 is a waveform diagram of each part of the circuit of the earth leakage protection system according to the second embodiment of the present invention.

FIG. 9 is a sensitivity current frequency characteristic diagram of an earth leakage breaker used in an earth leakage protection system according to a third embodiment of the present invention.

FIG. 10 is a circuit diagram showing a configuration of a high-sensitivity, high-speed earth leakage breaker (having the characteristic B of FIG. 9) used in the earth leakage protection system according to the third embodiment of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a middle-sensitivity time-delay type earth leakage breaker (having the characteristic A of FIG. 9) used in the earth leakage protection system according to the third embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a conventional earth leakage protection system for earth leakage at a commercial frequency.

FIG. 13 is a characteristic diagram of each of the earth leakage breakers used in the earth leakage protection system shown in FIG.

FIG. 14 is a circuit diagram illustrating a main configuration of a leakage detector used in a conventional high-speed and high-sensitivity leakage breaker.

15 is a waveform diagram of each part of the electric leakage detector shown in FIG.

FIG. 16 is a circuit diagram showing a configuration of a main part of a leakage detector used in a conventional medium-sensitivity extended-type ground leakage breaker.

FIG. 17 is a sensitivity current frequency characteristic diagram of the conventional earth leakage breaker shown in FIGS. 14 and 16;

[Explanation of symbols]

ELB1, ELB2… Medium sensitivity extension type earth leakage breaker, ELB
3, ELB4: High-speed, high-sensitivity earth leakage breaker, IM1, IM2 ...
Motor, INV: inverter, 1, 1a, 1b: IC,
2 ... Zero phase current transformer (ZCT), 3,4 ... Resistance, 5,5a,
5b, 5c, 10, 12: capacitor, 17: delay circuit, 18: output circuit, 26: characteristic changeover switch.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomiyoshi Kiryu 4-3 Kanda Surugadai, Chiyoda-ku, Tokyo Within Hitachi Techno Engineering Co., Ltd. (72) Inventor Hiroshi Ikeda 46-1 Tomioka, Nakajima-cho, Kitakanbara-gun, Niigata Pref. Inside Hitachi, Ltd. Nakajo Plant (72) Inventor Hideo Ishii 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Inside Hitachi Ltd. Nakajo Plant (72) Inventor Wataru Teraoka 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Inside the Hitachi, Ltd. Nakajo Plant

Claims (10)

[Claims] An output circuit connected to the leakage current detecting means for setting a sensitivity current characteristic with respect to frequency; and an output means connected to the frequency characteristic setting means. The current characteristics take a value of 30 mA at commercial frequency, take a value between 30 mA and 100 mA at 100 Hz, take a value between 100 mA and 1000 mA at 1 KHz, and increase with increasing frequency between 100 Hz and 1 kHz with increasing human body protection An earth leakage protection device characterized in that it is set to a characteristic that increases with an increase in frequency between 100 Hz and 1 kHz in relation to a characteristic of a threshold value for the earth leakage. 2. The apparatus according to claim 1, further comprising: a leakage current detection unit, a frequency characteristic setting unit connected to the leakage current detection unit for setting a sensitivity current characteristic with respect to a frequency, and an output unit connected to the frequency characteristic setting unit. The current characteristics take a value of 30 mA at commercial frequency, take a value between 30 mA and 100 mA at 100 Hz, take a value between 100 mA and 1000 mA at 1 KHz, and increase with increasing frequency between 100 Hz and 1 kHz with increasing human body protection A leakage protection device characterized in that the characteristic is set to a value smaller than the characteristic of the threshold value for 100 Hz to 1 kHz and increases with increasing frequency. 3. An apparatus comprising: a leakage current detection unit; a frequency characteristic setting unit connected to the leakage current detection unit for setting a sensitivity current characteristic with respect to frequency; and an output unit connected to the frequency characteristic setting unit. The current characteristics take a value of 30 mA at commercial frequency, take a value between 30 mA and 100 mA at 100 Hz, take a value between 100 mA and 1000 mA at 1 KHz, and increase with increasing frequency between 100 Hz and 1 kHz with increasing human body protection A leakage protection device characterized in that the characteristic is set to a characteristic that increases with an increase in frequency between 100 Hz and 1 kHz with a value greater than a characteristic of a threshold value for. 4. An apparatus comprising: a leakage current detecting means; a frequency characteristic setting means connected to the leakage current detecting means for setting a sensitivity current characteristic with respect to frequency; and an output means connected to the frequency characteristic setting means. The current characteristics take a value of 30 mA at commercial frequency, take a value between 30 mA and 100 mA at 100 Hz, take a value between 100 mA and 1000 mA at 1 KHz, and increase with increasing frequency between 100 Hz and 1 kHz with increasing human body protection The leakage protection device is set substantially in parallel with the threshold characteristic for 5. An earth leakage protection system comprising: a first earth leakage detecting unit configured to be connected to a load; and a second earth leakage detecting unit provided above the first earth leakage detecting unit. The first leakage detecting means includes first means for giving a characteristic in which a sensitivity current frequency characteristic changes at a value lower than a threshold having a predetermined current frequency characteristic determined for the purpose of protecting a human body; The leakage detection means of claim 1, further comprising a second means for providing a characteristic having a sensitivity current frequency characteristic having a value larger than that of the first leakage detection means. 6. The characteristic of the first leakage detecting means has a value of 30 mA at commercial frequency, a value between 30 mA and 100 mA at 100 Hz, and a value between 100 mA and 1000 mA at 1 KHz.
Is set to a characteristic that increases with an increase in frequency between 100 Hz and 1 kHz with a value smaller than the threshold characteristic for human body protection that increases with an increase in frequency between 1 and 1 kHz.
The characteristics of the ground fault detection means take a value of 30 mA at commercial frequency.
It takes a value between 30mA and 100mA at 100Hz and 100mA at 1KHz
Between 1000Hz and 1mA, with a value between 100Hz and 1kHz that increases with increasing frequency. The earth leakage protection system according to claim 5, wherein: 7. A first leakage detecting means configured to be connected to a load driven by a device that generates a leakage current containing a frequency component higher than a commercial frequency, and a higher level of the first leakage detecting means. In the earth leakage protection system comprising the second earth leakage detecting means provided in the above, the first earth leakage detecting means has a characteristic that the sensitivity current frequency characteristic changes at a value below a threshold value set for the purpose of protecting the human body. The first leakage detecting means has a sensitivity current frequency characteristic which is larger than the characteristic of the first leakage detecting means and has a sharply rising sensitivity current frequency characteristic near a commercial frequency. An earth leakage protection system comprising a second means for imparting characteristics. 8. A high-speed, high-sensitivity type leakage detecting means connected to a load, and one middle / low-sensitivity type leakage detecting means cascaded to the plurality of high-speed, high-sensitivity type leak detecting means. In a leakage protection system in which the plurality of high-speed and high-sensitivity leakage detection means and the medium and low-sensitivity leakage detection means are connected in protection coordination, at least one of the plurality of high-speed and high-sensitivity leakage detection means is provided. One is that a load driven by a device that is configured so that its sensitivity current frequency characteristic changes at a value lower than a threshold value determined for the purpose of protecting the human body and that generates a leakage current containing a frequency component higher than the commercial frequency is connected. It is arranged to be
An earth leakage protection system characterized in that the low-sensitivity type earth leakage detecting means is configured such that the sensitivity current frequency characteristic rises sharply in the vicinity of slightly exceeding the commercial frequency. 9. A high-speed, high-sensitivity type leakage detecting means connected to a load, and one middle / low-sensitivity type leakage detecting means cascaded to the plurality of high-speed, high-sensitivity type leakage detecting means. In a leakage protection system in which the plurality of high-speed and high-sensitivity leakage detection means and the medium and low-sensitivity leakage detection means are connected in protection coordination, at least one of the plurality of high-speed and high-sensitivity leakage detection means is provided. One is that a load driven by a device that is configured so that its sensitivity current frequency characteristic changes at a value lower than a threshold value determined for the purpose of protecting the human body and that generates a leakage current containing a frequency component higher than the commercial frequency is connected. It is arranged to be
The low-sensitivity leakage detection means is a sensitivity current frequency parallel to the sensitivity current frequency characteristic of the high-sensitivity high-speed leakage detection means to which a load driven by a device that generates a leakage current containing a frequency component higher than the commercial frequency is connected. An earth leakage protection system characterized by having characteristics. 10. A high-sensitivity, high-speed first leakage detecting means connected to an electric circuit in which a leakage current having a frequency component higher than the commercial frequency exists.・ Electronic Technical Commission (International Elec
trotechnical Commission (IEC) 479-2, a variable which is lower than the threshold value of ventricular fibrillation, and which is provided above the first leakage detecting means, is a middle / low-sensitivity time-delayed second leakage detection. An earth leakage protection system, characterized in that the means has a sensitivity current frequency characteristic which rises sharply in the vicinity of a frequency slightly higher than a commercial frequency.