JPH09224328A - Earth leakage breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of an earth leakage breaker while the malfunctioning caused by a noise is avoided by a method wherein a reference voltage value supplied to a signal comparison circuit unit or the amplification factor of a differential amplification unit is switched in accordance with resistance values corresponding to a plurality of sensitivity current values concerning an earth current. SOLUTION: A sensitivity setting unit 2 switches the set value of the sensitivity current of an earth leakage breaker 1 and outputs a sensitivity signal S2 corresponding to the set value of the sensitivity current. A variable resistance unit 3 switches a plurality of resistance elements in accordance with the inputted sensitivity signal S2 and a resistance value corresponding to the set value of the sensitivity current is obtained. A sensitivity conversion signal S3 which is matched with the voltage level of an earth conversion signal S1 outputted by a differential amplifier 81 is outputted by the variable resistance unit 3. An earth signal comparison circuit unit 4 outputs a comparison output signal Sa which is a voltage signal when the value of the earth conversion signal S1 exceeds the value of the sensitivity conversion signal S3 . Further, the amplification factor of the differential amplifier 81 is adjusted to obtain the earth conversion signal S1 corresponding to the set value of the sensitivity current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker capable of switching a set value of a sensitivity current and a time delay operation time, and has been improved so as to prevent a malfunction due to noise and reduce a price. Regarding configuration.

[0002]

2. Description of the Related Art A ground fault circuit breaker is widely used to prevent an accident due to a ground fault when a ground fault occurs in an AC power line. Among these earth leakage circuit breakers, there are known ones capable of switching the setting values of the sensitivity current and the time delay operation time, which are the values of the ground fault current for performing the interruption operation. Less than,
Several conventional examples of this type will be described with reference to the drawings. FIG. 5 is a circuit diagram of a conventional instantaneous action type earth leakage circuit breaker capable of switching the setting value of the sensitivity current. FIG.
, 9 is a main circuit contact 91 and a zero-phase current transformer 92.
And a resistor 93 for detection, a sensitivity setting unit 94, an operating unit 95, and a trip coil 97.

The main circuit contact 91 has a power supply side conductor 99a,
99b and the load side conductors 98a and 98b are connected. The zero-phase current transformer 92 includes an iron core and a load-side conductor 98.
It is well known that the ground current is included in the load current flowing through the load side conductors 98a and 98b through the a and 98b, and as is well known, it is proportional to the ground fault current from the output winding 921. The output current I ₀ is output. Resistor 93, output all or part of the current I ₀ flowed through and to generate a voltage V ₀ is No. There locations fault signal voltage having a value proportional to the output current I ₀ values at both ends thereof. The sensitivity setting unit 94 includes a changeover switch 941 having contacts a, b, and c, a resistor 942 connected to the contact b, and a resistor 94 connected to the contact c.
3 and a wiring board 944 on which the changeover switch 941, the resistors 942 and 943 are mounted. Reference numeral 949 is a lead wire that connects the sensitivity setting unit 94 and the resistor 93. The sensitivity setting unit 94 is connected in parallel to the resistor 93 in terms of an electric circuit, as shown in FIG.

The operating section 95 has an input terminal for inputting a signal and an output terminal for outputting a drive current Id for releasing the main circuit contact 91. The voltage V ₀ is input to the input terminal and this voltage is applied. The circuit device outputs the drive current Id from the output terminal when V ₀ exceeds a predetermined set value. When the drive current Id is supplied from the operating unit 95, the trip coil 97 reverses a main contact breaking mechanism (not shown) to release the main contact 91.
A fixed resistor or a semi-fixed resistor is used as the resistor 93, and the power of the operating unit 95 is generally supplied from between the load side conductors 98a and 98b. Since the earth leakage breaker 9 has the above-mentioned configuration, the output current I ₀ is the contact a at the changeover position of the changeover switch 941.
When it is set to 1, the entire current flows through the resistor 93, whereas when it is set to the contact b or the contact c, it is also shunted to the resistor 942 or the resistor 943. Therefore, when the changeover position of the changeover switch 941 is set to the contact b or the contact c, the voltage V ₀ generated in the resistor 93 has the output current I ₀ larger than that when it is set to the contact a. Therefore, the leakage current breaker capable of switching the sensitivity current value is obtained.

FIG. 6 is a circuit diagram of a conventional time-delay operation type earth leakage circuit breaker capable of switching the set value of the time-delay operation time. 6, the same parts as those of the earth leakage breaker shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.
Note that, in FIG. 6, only the representative reference numerals shown in FIG. 5 are described. In FIG. 6, reference numeral 8 denotes a sensitivity setting unit 9 in comparison with the earth leakage breaker 9 according to the conventional example shown in FIG.
4. Instead of the operation unit 95, a differential amplifier 81 which is a differential amplifier unit, a comparator 82, a reference voltage source 83A, a charging circuit unit 84, a time delay setting unit 85, a comparator 86 which is a time delay signal comparison circuit unit, and It is a time delay action type earth leakage circuit breaker including an operation unit 87.

The well-known differential amplifier 81 receives the voltage V ₀ output from the resistor 93, receives the voltage V ₀ , and is a voltage signal which corresponds to the voltage V ₀ and is not affected by the resistance value of the resistor 93. The envelope conversion signal S ₁ is output. Comparator 82 of collective wisdom is ground converts signals S ₁ to the non-inverting input terminal, the reference voltage of the ground-fault diverted supplied from the reference voltage source 83A to the inverting input terminal is inputted, the ground fault converted signals S ₁ When the value exceeds the reference voltage value, the comparison output signal Sa, which is a voltage signal, is output from the output terminal. Charging circuit section 84
Is a capacitor element 8 electrically connected in series with each other.
41 and a resistance element 842. The capacitor element 841 is charged through the resistance element 842 and the like when the comparison output signal Sa is applied to the charging circuit section 84,
The time delay signal St which is a voltage signal is output from both ends thereof.

A well-known comparator 86 has a time delay signal St at its non-inverting input terminal and a reference voltage source 83B at its inverting input terminal.
The reference voltages for the time delay operation supplied from the respective terminals are input, and when the value of the time delay signal St becomes equal to or more than the reference voltage value for the time delay operation, the output terminal outputs the operation signal Sd which is a voltage signal. The operating unit 87 has a DC voltage source 872 electrically connected in series to each other and a thyristor 871 which is a switching element, and electrically connects the trip coil 97 in series. The time delay setting unit 85 has contact points a,
changeover switch 851 having b and c, resistor 852 connected to contact b, and resistor 853 connected to contact c
And a wiring board 854 on which the changeover switch 851, the resistors 852 and 853 are mounted. This time delay setting section 8
5 is a resistor 842 in terms of an electric circuit as shown in FIG.
Are connected in parallel. 859 is a lead wire connecting the time delay setting unit 85 and the resistance element 842. Further, although the detailed illustration is omitted, the power sources of the reference voltage sources 83A and 83B and the DC voltage source 872 are generally supplied from between the load side conductors 98a and 98b.

Since the earth leakage breaker 8 has the above-described structure, the charging resistance for the capacitor element 841 is only the resistance element 842 when the changeover position of the changeover switch 851 is set to the contact a. When set to the contact b or the contact c, the resistance becomes the parallel resistance of the resistance element 842 and the resistor 852 or the parallel resistance of the resistance element 842 and the resistor 853. Therefore, when the switching position of the changeover switch 851 is set to the contact point b or the contact point c, the value of the time delay signal St, which is the charging voltage obtained by the capacitor element 841, is larger than that when it is set to the contact point a. Also, the reference voltage value for time delay operation is reached in a short charging time. As a result, the earth leakage breaker capable of switching the time delay operation time value is obtained.

[0009]

In the above-mentioned conventional earth leakage circuit breakers, for example, the earth leakage circuit breakers 8 and 9,
By setting the changeover switches 851 and 941 included in the time delay time setting unit 85 and the sensitivity setting unit 94, the time delay operation time and the set value of the sensitivity current can be changed. However, the following is a problem. It is getting closer. That is, in the earth leakage breaker 9, the wiring board 944 included in the sensitivity setting section 94 is manufactured as a wiring board separate from the wiring board on which the circuit elements configuring the operation section 95 and the like are mounted because of the structural necessity. It is often the case. Wiring board 94
4 and the wiring board on which the operating unit 95 and the like are mounted are manufactured as separate wiring boards, a lead wire (for example, a lead wire 949) that connects the sensitivity setting unit 94 and the operating unit and the like.
It is. ) Is something that requires some length. This long lead wire functions similarly to an antenna with respect to noise having a high frequency component, so that noise is easily generated. By the way, a voltage V ₀ which is a ground fault signal is applied to the lead wire 949, or a part of the output current I ₀ of the zero-phase current transformer 92 is passed.

An example of the current value flowing through the resistor 93 and the voltage value generated at the resistor 93 due to the output current I ₀ is shown below. When the sensitivity current value is set to 100 [mA], , 100 [μA] and 10 [m
V] It is extremely weak around. As a matter of course, the lead wire 949 is at a level similar to this.
Therefore, the occurrence of noise on the lead wire 949 means that noise is superimposed on the weak voltage V ₀ , so that the earth leakage breaker 9 is susceptible to malfunction due to the influence of high frequency noise. -ing This also applies to the earth leakage circuit breaker 8. In the earth leakage circuit breaker 8, the wiring board 854 of the time delay setting unit 85 is manufactured as a wiring board separate from the wiring board on which other circuit elements are mounted. In many cases, even with the earth leakage breaker 8, the lead wire 859
Since noise is generated in the, noise is likely to be generated and malfunction is likely to occur. Further, since the changeover switch 941 included in the earth leakage breaker 9 switches the weak voltage / current as described above, it is necessary to improve the contact reliability of the contact portion. It is necessary to use it, which increases the manufacturing cost of the earth leakage breaker 9. Further, in the case of the earth leakage breaker 8, in order to reduce the manufacturing cost of the earth leakage breaker 8 or the like, it is desired to try to reduce the capacitance value of the capacitor element 841 included in the charging circuit unit 84.
Since the time delay operation time value defined by the standard cannot be changed, the reduction of the electrostatic capacitance value directly leads to the reduction of the charging current value. The reason why the charging current value is made weak is the same as that already described in the section, and the changeover switch 851 of the earth leakage breaker 8 has a high contact reliability such as gold-plated contacts. You will have to use switches. Therefore, whichever is selected, the manufacturing cost of the earth leakage breaker 8 increases. Furthermore, although not mentioned in the above description, some earth leakage circuit breakers are also used which are capable of switching the setting values of both the sensitivity current and the time delay operation time. In the case of such an earth leakage breaker, the sensitivity setting unit 94
Since it is necessary to include both the time delay setting unit 85 and the time delay setting unit 85, two lead wires 949 and 859 are provided as lead wires.
Is required. This wiring of a total of four lead wires requires a relatively long work man-hour because the work is complicated, and the manufacturing cost of this type of earth leakage circuit breaker increases. There is.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide an earth leakage breaker improved so as to reduce the cost while preventing malfunction due to noise. It is in.

[0012]

The above-mentioned objects of the present invention are as follows: 1) a main circuit contact, a zero-phase current transformer for detecting a ground fault current contained in a current flowing through the main circuit contact, and a zero-phase current transformer. A resistor for detection that converts the current output from the phase current transformer into a ground fault signal that is a voltage, a differential amplifier that inputs the ground fault signal, and multiple sensitivity current values related to the ground fault current are set to appropriate values. The sensitivity setting section outputs the sensitivity signal corresponding to the sensitivity current value by switching the setting to, the variable resistance section for inputting the sensitivity signal to obtain the resistance value corresponding to the sensitivity current value, and the differential amplifier section. One input terminal to which the signal corresponding to the ground fault signal is input, the other input terminal to which the reference voltage for the ground fault current is input, and the level of the signal corresponding to the ground fault signal is the value of the reference voltage or more. And a ground fault signal comparison circuit section having an output end for outputting a comparison output signal, And the operation part that releases the main circuit contact when a force signal is output, and based on the resistance value obtained by the variable resistance part, the value of the reference voltage applied to the signal comparison circuit part or the differential Or 2) In the means described in the above item 1, the variable resistance section converts the sensitivity signal, which is an analog signal, into a binary signal.
A converter for inputting the binary signal and outputting a binary signal having the same number of bits as the number of switching stages of the sensitivity current value; and inputting a plurality of binary signals output from the decoder, A configuration having a switching element that is turned on / off corresponding to the level of the binary signal and a resistance element section whose resistance value is switched by this switching element, or 3) a main circuit contact and a main circuit A zero-phase current transformer that detects the ground-fault current contained in the current flowing through the contact, a detection resistor that converts the current output by the zero-phase current transformer into a ground-fault signal that is a voltage, and a ground A differential amplifier for inputting a ground fault signal, one input terminal for receiving a signal corresponding to the ground fault signal output from the differential amplifier, and the other input for receiving a reference voltage for ground fault current Edge and signal level corresponding to ground fault signal Is equal to or greater than the reference voltage value for the ground fault current, the ground fault signal comparison circuit section having an output terminal for outputting a comparison output signal, and the time delay operation time value is switched to an appropriate value to set the time delay operation. A time delay setting unit that outputs a time delay signal corresponding to a time value, and a plurality of switches, and closes only one specific switch corresponding to the time delay operation time value of the input time delay signal. It has a switching unit, a resistance element and a capacitor element electrically connected in series with each other, and when the comparison output signal is output from the ground fault signal comparison circuit section, charging of the capacitor element by the charging power supply is started, A time delay signal generator that outputs a time delay signal from both ends of the capacitor element, one input terminal to which the time delay signal is input, and the other input terminal to which the reference voltage for the time delay signal is input. The signal level exceeds the value of the reference voltage for the time delay signal. Then, there is provided a time delay signal comparison circuit section having an output end for outputting an operation signal, and an operation section for releasing the main circuit contact when the operation signal is output, and the switch closed by the switching section. On the basis of the above, the configuration is such that the time delay operation time value is switched by switching the charging condition for the capacitor element of the time delay signal generation section or by switching the value of the reference voltage for the time delay signal. Or 4) In the means described in the above item 2, the switching section inputs an A / D conversion section for converting a time delay signal which is an analog signal into a binary signal and a time delay by inputting the binary signal. A decoder that outputs a binary signal having the same number of bits as the number of operating time value switching stages and a plurality of binary signals output from the decoder are input to each of the decoders, and the on-signal is turned on in accordance with the level of the binary signal. Switching element to turn off Or 5) In the means described in any one of the items 2 to 4, the sensitivity setting unit and the time delay setting unit are a resistance element for setting the sensitivity current and a time delay. Of the setting ladder resistance, which has a resistance element for setting the operating time and which has one end grounded, and which has a changeover switch for switching the resistance element for setting the sensitivity current among the setting ladder resistance, The switch for switching the resistance element for the time delay operation time and the constant current source that is connected to the anti-ground side of the setting ladder resistor and supplies a constant value of direct current to the setting ladder resistor. The A / D conversion unit, which serves as a setting unit and is included in the variable resistance unit excluding the resistance element unit and the switching unit, includes a conversion ladder resistor and a direct current that supplies a constant value of direct current or DC voltage to the conversion ladder resistor. Power supply , The DC voltage obtained at the connection point between the setting ladder resistance of the setting section and the constant current source is commonly input to the non-inverting input terminal, and the different resistance elements that compose the conversion ladder resistance are connected to the inverting input terminal. It is achieved by a configuration in which a DC voltage obtained at a connection point is integrally configured with a plurality of comparators to which each is input, and a binary signal is output from each output terminal of the plurality of comparators. It

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram for explaining an embodiment of an earth leakage breaker according to the present invention. In FIG. 1, the same parts as those of the conventional earth leakage breaker shown in FIGS. 5 and 6 are designated by the same reference numerals, and the description thereof will be omitted. In addition, in FIG. 1, as for the reference numerals given in FIGS. 5 and 6, only representative reference numerals are shown. In FIG. 1, reference numeral 1 denotes a sensitivity setting unit 2, a DC power supply 3A, a variable resistance unit 3, a ground fault signal comparison circuit unit 4, a time delay setting unit 5, with respect to the earth leakage breaker 8 according to the conventional example shown in FIG. DC power supply 6A, switching unit 6 and time delay signal generating unit 7, variable resistance unit 3B provided as needed in place of variable resistance unit 3, and variable reference voltage provided as needed in place of switching unit 6 This is an earth leakage circuit breaker including a generation circuit unit 6B or a charging condition switching unit 7A. Here, the earth leakage breaker 1 is shown as an earth leakage breaker capable of switching between both the set values of the sensitivity current and the time delay operation time for convenience of description.

The sensitivity setting unit 2 is a circuit unit for switching the setting value of the sensitivity current of the earth leakage breaker 1 and outputting the sensitivity signal S ₂ corresponding to the setting value of the sensitivity current. It has the same function as the sensitivity setting unit 94 according to the conventional example shown. However, the sensitivity setting unit 2 is configured so that the voltage / current value given to the changeover switch is more advantageous than the case of the sensitivity setting unit 94 in terms of maintaining contact reliability of the contact portion of the changeover switch. That is different. The variable resistance unit 3 has a plurality of resistance elements, and obtains a resistance value corresponding to the set value of the sensitivity current by switching these resistance elements according to the input sensitivity signal S _2. It is the circuit part. By supplying a DC voltage or current of a constant value from the DC power supply 3A to the resistance element of the variable resistance unit 3, the variable resistance unit 3 outputs the ground fault conversion signal S output from the differential amplifier 81. _A sensitivity conversion signal S ₃ that is a sensitivity signal adapted to the voltage level of ₁ is output. That is, in the circuit unit in which the DC power supply 3A and the variable resistance unit 3 are integrated, the ground fault conversion signal S ₁ has the level of the sensitivity signal S ₂ having a voltage level advantageous for maintaining the contact reliability of the contact unit. This is a circuit unit for converting the level into the sensitivity conversion signal S ₃ having a value suitable for the voltage level. The ground fault signal comparison circuit unit 4 will be described in the case of using a well-known comparator. The ground fault conversion signal S is applied to its non-inverting input terminal.
_{When the value 1} of the sensitivity conversion signal S ₃ is input to the inverting input terminal and the value of the ground fault conversion signal S ₁ becomes greater than or equal to the value of the sensitivity conversion signal S ₃ , the comparison output signal S which is a voltage signal from the output end.
It is a circuit unit that outputs a.

The time delay setting section 5 is a circuit section which switches the time delay operation time set value of the earth leakage breaker 1 and outputs a time delay signal S ₅ corresponding to the time delay operation time set value. In this respect, it has the same function as the time delay setting unit 85 according to the conventional example shown in FIG. However, in the time delay setting section 5, as in the sensitivity setting section 2, the voltage / current value applied to the changeover switch is
It is different from the case of the time delay setting unit 85 in that it is configured to have a more advantageous value from the viewpoint of maintaining contact reliability of the contact portion of the changeover switch. The switching unit 6 is a circuit unit having a plurality of switches and having a function of closing only one specific switch corresponding to the time delay operation time value of the input time delay signal S ₅ . Each switch of the switching unit 6 is connected to a plurality of DC power supplies having different voltage values of the DC power supply 6A, and each switch of the switching unit 6 is connected to each DC power supply of the DC power supply 6A. As a result, the switching unit 6 outputs the charging voltage V ₆ having a value suitable for charging the capacitor element 841 for charging.

That is, in the circuit section in which the DC power supply 6A and the switching section 6 are integrated, the capacitor element 841 is charged with the level of the time delay signal S ₅ having a voltage level advantageous for maintaining the contact reliability of the contact section. The circuit unit converts the level to the charging voltage V ₆ having a value adapted to. The time delay signal generation unit 7 includes a switching element 71 that is on / off controlled by the comparison output signal Sa output from the ground fault signal comparison circuit unit 4, and a charging circuit unit. As the switching element 71, an appropriate switching element including various semiconductor switching elements can be used as long as it can be turned on / off by the comparison output signal Sa.

The charging circuit section is basically composed of a capacitor element 841 and a resistance element 842. When the comparison output signal Sa is output, the time delay signal generation unit 7 turns on the switching element 71 to start charging the capacitor element 841 with the charging voltage V _{6 and} to output a voltage signal from both ends of the capacitor element 841. Some time delay conversion signal St
Is output. The time delay conversion signal St is supplied to the non-inverting input terminal of the comparator 86 and the inverting input terminal thereof is supplied from the reference voltage source having a constant DC voltage value as in the case of the conventional example shown in FIG. The reference voltage for the time delay operation is input. Then, when the value of the time delay conversion signal St becomes equal to or higher than the reference voltage value for the time delay operation, the operation signal Sd which is a voltage signal is output from the output end. Further, since the voltage level applied to the lead wire connecting the sensitivity setting unit 2, the time delay setting unit 5, and the other circuit unit is set to a value larger than that in the case of the conventional example described above. Even if a noise voltage is generated in this lead wire, the degree of influence of this noise voltage is reduced as compared with the case of the above-mentioned conventional example.

In the above description, the circuit section which operates in response to the sensitivity signal S ₂ is the variable resistance section 3, but
It is also possible to use the variable resistance part 3B (indicated by a thick dotted line in FIG. 1) instead of the variable resistance part 3. Variable resistance part 3
B has a plurality of resistance elements, and these resistance elements are switched according to the input sensitivity signal S ₂ to obtain a resistance value corresponding to the set value of the sensitivity current. It is the circuit part. In this case, as is well known, the variable resistance section 3B functions as a feedback resistance to the differential amplifier 81, and the resistance value of the variable resistance section 3B is changed to change the differential amplifier 8.
By adjusting the amplification factor of 1, the ground fault conversion signal S ₁ having a value corresponding to the setting value of the sensitivity current is obtained. In this case, as in the case of the conventional example shown in FIG.
The reference voltage for the ground fault current supplied from the reference voltage source having a constant DC voltage value is input. The variable resistance unit 3B is connected between any input terminal of the differential amplifier 81 and the output terminal of the differential amplifier 81 in accordance with the amplification method of the amplification circuit unit including the differential amplifier 81. It

In the above description, the circuit section which operates in response to the time delay signal S ₅ is the switching section 6, but
It is also possible to use the variable resistance portion 7A (shown by a thick dotted line in FIG. 1) instead of the switching portion 6. Variable resistance part 7A
Is used in place of the resistance element 842 of the time delay signal generation section 7, and has a plurality of resistance elements in the same manner as the variable resistance section 3B. The circuit unit is configured to obtain the resistance value for charging corresponding to the set value of the time delay operation time by switching it according to S ₅ . By adjusting the charging current value for the capacitor element 841 by changing the resistance value of the variable resistance unit 7A, the time delay conversion signal St having a value corresponding to the set value of the time delay operation time is obtained. is there. In this case, in the variable resistance section 7A, instead of the DC power source 6A,
A DC voltage source having a constant DC voltage value is used as the charging voltage source.

Further, as the circuit section which operates in response to the time delay signal S ₅ , it is possible to use the variable reference voltage generating circuit section 6B (shown by a thick dotted line in FIG. 1) instead of the switching section 6. Is. The variable reference voltage generation circuit section 6B is used in place of the reference voltage source for the time delay operation which is input to the inverting input terminal of the comparator 86. For example, the variable resistance section 3 and the DC power source 3A are used. With the same configuration as that of the integrated circuit section, an attempt is made to obtain a reference voltage value for time delay operation having a value corresponding to the set value of the time delay operation time. In this case, the time delay signal generation unit 7 determines the time delay signal S ₅
Regardless of the above, the capacitor element 841 is charged with a constant charging voltage and charging resistance.

In the earth leakage breaker 1 configured as shown in FIG. 1 described above, the sensitivity setting unit 2 for setting the sensitivity current value and the time delay setting unit 5 for setting the time delay operation time value are provided. ,
Since the part to which the voltage V ₀ is applied and the capacitor element 841 are electrically separated from each other, the voltage and current levels used are advantageous in maintaining contact reliability of the contact portion of the changeover switch. It is possible to set a larger value than the case. As a result, the changeover switches of the sensitivity setting section 2 and the time delay setting section 5 use a general changeover switch which is not subjected to the contact resistance improvement process such as gold plating unlike the conventional example. It becomes possible. Further, as a result, the electrostatic capacitance value of the capacitor element 841 can be set regardless of the contact reliability of the contact portion of the changeover switch being maintained.
It is possible to select a capacitor element having a small capacitance value for 41.

Further, the earth leakage breaker 1 described above is an earth leakage breaker capable of switching the setting values of both the sensitivity current and the time delay operation time. However, in the embodiment shown in FIG. 1, by applying the corresponding portions, it is possible to switch only the set values of the leakage current breaker and the time delay operation time that enable only the set values of the sensitivity current. Needless to say, the present invention can also be applied to an earth leakage circuit breaker.

[0023]

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description of this section, the same parts as those of the earth leakage breaker according to the embodiment of the present invention shown in FIG. 1 and the conventional earth leakage breaker shown in FIGS. Is attached and the description thereof is omitted. Further, in the drawings used for the description of this section and thereafter, only the representative reference numerals are shown for the reference numerals given in FIGS. 1, 5 and 6.

Embodiment 1 FIG. 2 is a circuit diagram of an instantaneous action type earth leakage breaker capable of switching the set value of the sensitivity current according to an embodiment of the present invention corresponding to claims 1 and 2. In FIG. 2, 1A is a differential amplifier 81 and a sensitivity setting unit 2 which are differential amplifying units in place of the sensitivity setting unit 94 and the operating unit 95 in the earth leakage breaker 9 according to the conventional example shown in FIG. , A DC power supply 3A, a variable resistance unit 3, and a ground fault signal comparison circuit unit 4. The sensitivity setting unit 2 includes a changeover switch 21 having three contacts, a resistance element 22 and 23 electrically connected in series with each other, and a constant value direct current to the resistance elements 22 and 23, like the changeover switch 941 of the conventional example. It has a DC constant current source device 24 for supplying a current. The series connection of the resistance elements 22 and 23 is connected to the contacts of the changeover switch 21 as shown in FIG.
The anti-resistance element 23 side of the resistance element 22 is connected to the ground potential, and the anti-resistance element 22 side of the resistance element 23 is connected to the DC constant current source device 24. Then, the sensitivity signal S ₂ is output from the connection point between the resistance element 23 and the DC constant current source device 24. The value of the sensitivity signal S ₂ is changed according to the contact switching position of the changeover switch 21. The features of the sensitivity setting unit 2 which the conventional example has with respect to the sensitivity setting unit 94 are as described in the embodiment of the invention. Then, the value of the circuit voltage given to the sensitivity setting section 2 for outputting the sensitivity signal S ₂ is set to about 5 [V] to 10 [V] from the above. In addition, instead of the DC constant current source device 24,
It is also possible to use a DC constant voltage source device that supplies a constant DC voltage. The variable resistance unit 3 includes the A / D conversion unit 31.
A decoder 35, a group of transmission gates (hereinafter abbreviated as TG) 36, which are switching elements, and three resistance elements 37 connected in ladder.
A, 37B, and 37C. A / D converter 31
Are three resistance elements 32A, 32B connected in ladder,
32C and the sensitivity signal S ₂ to the non-inverting input terminal, and the comparator 3 for inputting the connection point potential of the resistance elements 32A, 32B and 32C to the inverting input terminal as shown in FIG.
3A and 33B and a DC constant voltage source device 34 for supplying a constant DC current to the resistance elements 32A, 32B and 32C. The A / D converter 31 inputs the sensitivity signal S ₂ which is an analog signal having three levels of values, and outputs 2 bits from each of the output terminals of the comparators 33A and 33B (the number of switching contacts of the selector switch 21 is 3). Therefore, it is the number of bits corresponding to the number of stages 3 of the sensitivity signal S _2. ) (Divided by A and B.) Binary signal [High level (hereinafter sometimes abbreviated as “H”). It means a digital signal having only two levels of either low level (hereinafter sometimes abbreviated as "L"). ] It is a circuit device that outputs S ₃₁ .

The decoder 35 is installed to convert the binary signal S ₃₁ into a binary signal S _35A of 3 bits (divided by X, Y and Z) in the same number as the number of switching stages of the sensitivity current value. . Binary signals S ₃₁ , S for the sensitivity signal S ₂
The relationship of the levels of _35A is as shown in Table 1. The TG group 36 includes TGs 36A, 36B, and 36C, which are the same in number as the number of bits of the binary signal S _35A.
Each of A, 36B, and 36C inputs the signal of each bit of the binary signal S _35A , and outputs the binary signal S of "H".
Only _35A (see Table 1) input is turned on. Resistance elements 37A, 3 connected in ladder
7B and 37C, as shown in the figure, DC power supply 3A and TG
One ends of 36A, 36B and 36C are connected, and the other ends of TGs 36A, 36B and 36C are grouped together, and the sensitivity conversion signal S ₃ is output from this part. The level value of the sensitivity conversion signal S ₃ is a value obtained by dividing the DC power supply 3A by the resistance elements 37A, 37B and 37C. That is, the level value of the sensitivity conversion signal S ₃ is
DC power source 3 regardless of the level of sensitivity signal S ₂
By appropriately setting, for example, the voltage value supplied by A, the voltage level of the ground fault conversion signal S ₁ can be adapted.

[0026]

[Table 1] In the comparator 4 which is the ground fault signal comparison circuit unit, the ground fault conversion signal S ₁ is input to its non-inverting input terminal and the sensitivity conversion signal S ₃ is input to its inverting input terminal, and the value of the ground fault conversion signal S ₁ is the sensitivity. It is a circuit unit that outputs the comparison output signal Sa, which is a voltage signal, from the output end when the value of the converted signal S ₃ or more is reached. This comparison output signal Sa in the earth leakage breaker 1A is
Operation signal S in the case of the conventional earth leakage breaker 8 shown in FIG.
In the operation unit 87, which performs exactly the same function as d, and the comparison output signal Sa is input, the thyristor 871 is turned on, so that the trip coil 97 becomes the main contact 91 as in the conventional example.
Perform the action of releasing. The action and effect of the earth leakage breaker 1A according to the embodiment shown in FIG. 2 are the same as the action and effect of the relevant portion of the earth leakage breaker 1 described in the embodiment of the invention, so avoid duplication. The description will be omitted.

Embodiment 2; FIG. 3 is a circuit diagram of a time delay action type earth leakage circuit breaker capable of switching the set value of the time delay action time according to an embodiment of the present invention corresponding to claims 3 and 4. Is. In FIG. 3, the same parts as those of the earth leakage circuit breaker according to the embodiment of the present invention corresponding to claims 1 and 2 shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 3, reference numeral 1B is different from the earth leakage breaker 8 according to the conventional example shown in FIG. Power supply 6
It is an earth leakage breaker including A, a switching unit 6 and a time delay signal generating unit 7. The time delay setting unit 5 includes a changeover switch 85 of the conventional example.
A change-over switch 51 having three contacts as in the case of 1, a resistance element 52, 53 electrically connected in series to each other, and a DC constant current source device 54 for supplying a constant value DC current to the resistance element 52, 53. Have

The series connection of the resistance elements 52 and 53 is connected to the contacts of the changeover switch 51 as shown in FIG. 3, and is connected to the ground potential on the side of the resistance element 52 opposite to the resistance element 53. The anti-resistance element 52 side of the resistance element 53 is connected to the DC constant current source device 54. Then, the time delay signal S ₅ is output from the connection point between the resistance element 53 and the DC constant current source device 54. At this time, the value of the time delay signal S ₅ is changed according to the contact switching position of the changeover switch 51. The features of the time delay setting unit 2 with respect to the conventional time delay setting unit sensitivity setting unit 94 are as described in the embodiments of the invention. For this reason, a circuit provided in the time delay setting unit 2 The voltage value is also the same as that of the sensitivity setting unit 2 included in the earth leakage breaker 1A described above. Instead of the DC constant current source device 54, it is also possible to use a DC constant voltage source device that supplies a DC voltage having a constant value.

The switching unit 6 is a circuit having the same structure as the rest of the variable resistance unit 3 of the earth leakage breaker 1A according to the present invention shown in FIG. 2 except for the resistance elements 37A, 37B and 37C. It is a department. In addition, in FIG.
Each bit of the binary signal S ₃₁ of bits is divided into C and D, and the 3-bit binary signal output from the decoder 35 is attached with the sign of the binary signal S _35B , and each bit is U. , V, W. In the case of this example, the DC power supply 6A has the number of switching contacts of the changeover switch 51 of 3
It has the same number of DC power supplies 61, 62, 63. The DC power supplies 61, 62, 63 have different voltage values corresponding to the set values of the three-step time delay operation times of the time delay signal S ₅ . DC power supply 61, 62, 63
Are the TGs 36A, 36B, 3 of the switching unit 6, respectively.
6C is connected to one end of the
From the signal output terminal of the switching unit 6 in which the other ends of 36A, 36B, and 36C are integrated, a charging voltage V ₆ having a value suitable for charging the capacitor element 841 for charging, which will be described later, is output. The voltage value of this charging voltage V ₆ is the sensitivity signal S
Regardless of the level of ₅ , the sensitivity signal S ₅ is set by appropriately setting, for example, the voltage value supplied from the DC power supply 6A.
Capacitor element 841 adapted to the time delay operating time
Can be charged.

The time delay signal generating section 7 has a charging circuit section composed of a MOSFET 71 which is a voltage driving type switching element, a capacitor element 841 and a resistance element 842. The elements of this are connected in series with one another as shown in FIG. The charging voltage V ₆ is input to the main pole of the MOSFET 71 on the side opposite to the charging circuit.
The MOSFET 71 is turned on when the comparison output signal Sa becomes "H", and turned off when the comparison output signal Sa becomes "L". When the MOSFET 71 is turned on,
By applying the charging voltage V ₆ to the charging circuit section, the capacitor element 841 is charged through the resistance element 842, and the time delay signal St which is a voltage signal is output from both ends thereof. This is similar to the case of the conventional earth leakage breaker 8 shown in FIG. 6, and the operation of the earth leakage breaker 1B after the time delay signal St is therefore completely different from that of the conventional earth leakage breaker 8. It is the same. The actions and effects of the earth leakage breaker 1B according to the embodiment shown in FIG. 3 are the same as the actions and effects of the relevant portion of the earth leakage breaker 1 described in the embodiment of the invention, so avoid duplication. The description will be omitted.

Embodiment 3; FIG. 4 shows a time-delay operation type earth leakage circuit breaker capable of switching both set values of a sensitivity current and a time-delay operation time according to an embodiment of the present invention corresponding to claim 5. It is a circuit diagram of a main part. 4, an earth leakage breaker according to an embodiment of the present invention corresponding to claims 1 and 2 shown in FIG. 2 and an embodiment of the present invention corresponding to claims 3 and 4 shown in FIG. The same parts as those of the earth leakage breaker are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 4, 1C is an earth leakage circuit breaker 1A according to the present invention shown in FIG. 2 and an earth leakage circuit breaker 1B according to the present invention shown in FIG.
It is an earth leakage circuit breaker that combines and has the function of. The earth leakage breaker 1C includes a sensitivity setting unit 2 included in the earth leakage breaker 1A.
And a time delay setting unit 5 included in the earth leakage breaker 1B, a setting unit 2A, an A / D conversion unit 31 included in a variable resistor unit 3 included in the earth leakage breaker 1A, and an earth leakage breaker 1B. The A / D conversion unit 31A integrally having the function of the A / D conversion unit 31 of the switching unit 6, the decoder 35 of the variable resistance unit 3 of the earth leakage breaker 1A, and the earth leakage breaker 1B are provided. The decoder 35A provided with the function of the decoder 35 of the switching unit 6 and the decoder 35A having the integrated function is a structural feature of the earth leakage breakers 1A and 1B.

The setting unit 2A supplies a constant DC current i to a setting ladder resistor in which the resistance elements 22 and 23 and the resistance elements 52 and 53 are all connected in a ladder shape. It has a device 24A. The resistance elements 22, 23, 52, 53 of the setting ladder resistor are connected to the contacts of the changeover switches 21, 51 as shown in FIG. 4, and the end of the resistance element 52 is connected to the ground potential. It is connected and is connected to the DC constant current source device 24A at the end of the resistance element 23. Then, the setting signal S _2A is output from the connection point between the resistance element 23 and the DC constant current source device 24A. The value of the setting signal S _2A is changed corresponding to the contact switching positions of the changeover switch 21 and the changeover switch 51, which are set positions. Then, this setting signal S _2A
The value of i depends on the setting position of the changeover switches 21 and 51.
× (R23 + R22 + R53 + R52), i × (R23
+ R22 + R53), i × (R23 + R22), i ×
(R23 + R53 + R52), i × (R23 + R5)
3), i × R23, i × (R53 + R52), i × R5
It will be one of nine values of 3 and zero volts.

The A / D converter 31A includes a resistance element 32D,
32E, 32F, 32F, 32G, 32H, 32I, 3
2J, 32K, 32L conversion ladder resistor consisting of a total of nine resistance elements, DC constant voltage source device 34A for supplying a constant value DC current to the conversion ladder resistor, and non-inverting input terminal Comparators 33C, 33D, 33E, 33 for inputting the signal S _{2A and} for inputting the connection point potentials of the resistance elements 32A to 32L to the inverting input terminals as shown in FIG.
It has F, 33G, 33H, 33I, and 33J.
The A / D conversion unit 31A is a circuit device that inputs the setting signal S _2A and outputs an 8-bit binary signal S _31A (classified by E to L) from each of the output terminals of the comparators 33C to 33J. is there. The decoder 35A is the binary signal S _31A, the binary signal S of the switching stages and the same number of 3 bit sensitivity current value (X, Y, dividing by Z.)
_35A and a 3-bit binary signal _{S35B of the} same number as the number of switching stages of the time delay operation time value (divided by U, V, W).
It is installed to convert to and. The relation between the levels of the binary signals S _31A , S _35A and S _35B with respect to the setting signal S _2A is as shown in Table 2. The binary signal S
Since the supply destinations of _35A and _S35B are the same as those of the earth leakage breaker 1A and the earth leakage breaker 1B, the description thereof will be omitted to avoid duplication. Although the earth leakage breaker 1C configured as shown in FIG. 4 is capable of switching both the setting values of the sensitivity current and the time delay operation time, the setting unit 2A does not change the sensitivity current and the time delay time as described above. The signals of both set values of the operating time are collectively output. As a result, the number of lead wires for transmitting the setting signal S _2A , which is a signal of both the setting values of the sensitivity current and the time delay operation time, is half that of the conventional technique. Since only two lead wires for transmitting the setting signal S _2A are required, the earth leakage breaker 1C is the same as the earth leakage breaker 1 described above.
In addition to the functions and effects of A and the earth leakage breaker 1B, it is possible to reduce the man-hours required for the lead wire wiring work.

[0034]

[Table 2]

[0035]

According to the present invention, the following effects can be obtained by adopting the structure described in the section for solving the above-mentioned problems. By adopting the configuration according to item (1) of the means for solving the problem, the voltage and current values handled by the changeover switch of the sensitivity setting section are not at a level that can be handled by normal contacts. Therefore, it is possible to obtain sufficient contact reliability even with a general changeover switch, and it is possible to reduce the manufacturing cost of the earth leakage breaker. Further, since the voltage level applied to the lead wire connecting the sensitivity setting section and the other circuit section can be made high, it is possible to reduce the influence of the noise voltage generated in the lead wire, and the reliability of the earth leakage breaker is improved. It is also possible to improve productivity. Further, by adopting the configuration according to the item (2) of the means for solving the problem, the level of the signal obtained by the sensitivity setting unit can be converted by the digital circuit, and the influence of the variation of the circuit element used can be reduced. Since the cost can be reduced, it is possible to further reduce the manufacturing cost of the earth leakage circuit breaker that achieves the effects of the above items. Further, by adopting the configuration according to item (3) in the section of means for solving the problem, it is possible to handle the voltage / current value handled by the changeover switch of the time delay setting section by the normal contact. Since the level can be achieved, sufficient contact reliability can be obtained even with a general changeover switch, and the manufacturing cost of the earth leakage breaker can be reduced. Further, since the voltage level applied to the lead wire connecting the time delay setting section and the other circuit section can be made high, it is possible to reduce the influence of the noise voltage generated in the lead wire, and It is also possible to improve reliability. Further, since the capacitance value of the capacitor element forming the charging circuit section can be made small, the manufacturing cost of the earth leakage breaker can be reduced also from this point. In addition, by adopting the configuration according to item (4) of the means for solving the problem, the signal obtained by the time delay setting unit can be level-converted by a digital circuit, and the influence of variations in circuit elements used. And the like, it is possible to further reduce the manufacturing cost of the earth leakage circuit breaker that achieves the effects of the above items. Furthermore, in the earth leakage breaker capable of switching between both the set values of the sensitivity current and the time delay operation time by adopting the configuration according to the item (5) of the means for solving the problem, both set values can be changed. The number of lead wires drawn from the setting section for
Since it is possible to reduce the cost to half that in the case of the conventional technique, it is possible to further reduce the manufacturing cost of the earth leakage circuit breaker that can obtain the effects of the above items (1) to (3).

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram illustrating an embodiment of an earth leakage breaker according to the present invention.

FIG. 2 is a circuit diagram of an instantaneous action type earth leakage circuit breaker capable of switching the setting value of the sensitivity current according to an embodiment of the present invention corresponding to claims 1 and 2.

FIG. 3 is a circuit diagram of a time delay action type earth leakage circuit breaker capable of switching a set value of a time delay action time according to an embodiment of the present invention corresponding to claims 3 and 4.

FIG. 4 is a circuit diagram of a main portion of a time-delay operation type earth leakage circuit breaker capable of switching both setting values of a sensitivity current and a time-delay operation time according to an embodiment of the present invention corresponding to claim 5;

FIG. 5 is a circuit diagram of a conventional instantaneous action type earth leakage circuit breaker capable of switching the setting value of the sensitivity current.

FIG. 6 is a circuit diagram of a conventional time-delay operation type earth leakage circuit breaker capable of switching the set value of the time-delay operation time.

[Explanation of symbols]

 1 Leakage breaker 2 Sensitivity setting section 3 Variable resistance section 3A DC power supply 4 Ground fault signal comparison circuit section 5 Time delay setting section 6 Switching section 6A DC power supply 7 Time delay signal generating section 71 Switching element

Claims (5)

[Claims] 1. A main circuit contact, a zero-phase current transformer for detecting a ground fault current contained in a current flowing through the main circuit contact, and a ground fault which is a voltage output from the zero-phase current transformer. A detection resistor that converts the signal into a signal, a differential amplifier that inputs the ground fault signal, and a sensitivity signal that corresponds to the sensitivity current value by switching and setting multiple sensitivity current values related to the ground fault current to appropriate values. Of a sensitivity setting unit, a variable resistance unit that inputs a sensitivity signal to obtain a resistance value corresponding to a sensitivity current value, and a signal that corresponds to the ground fault signal output from the differential amplifier unit. Input end,
A ground fault signal comparison circuit having the other input end to which the reference voltage for the ground fault current is input and an output end for outputting a comparison output signal when the level of the signal corresponding to the ground fault signal exceeds the value of the reference voltage. Section, and an operation section that performs an operation of releasing the main circuit contact when a comparison output signal is output, based on the resistance value obtained by the variable resistance section, the value of the reference voltage to be given to the signal comparison circuit section, Alternatively, the earth leakage breaker is characterized in that the amplification factor of the differential amplifier is switched. 2. The earth leakage breaker according to claim 1, wherein the variable resistance section receives an A / D conversion section for converting a sensitivity signal, which is an analog signal, into a binary signal, and the binary signal. A decoder that outputs a binary signal with the same number of bits as the number of switching steps of the sensitivity current value, and a plurality of binary signals output from the decoder are input to each of them, and the on / off signal is turned on according to the level of the binary signal. An earth leakage circuit breaker, comprising: a switching element that is turned off; and a resistance element portion whose resistance value is switched by the switching element. 3. A main circuit contact, a zero-phase current transformer for detecting a ground fault current contained in a current flowing through the main circuit contact, and a ground fault which is a voltage output from the zero-phase current transformer. A detection resistor for converting into a signal, a differential amplification unit for inputting a ground fault signal, one input end to which a signal corresponding to the ground fault signal output from the differential amplification unit is input, and a ground fault. A ground fault having the other input end to which the reference voltage for the current is input and an output end for outputting the comparison output signal when the level of the signal corresponding to the ground fault signal becomes equal to or higher than the value of the reference voltage for the ground fault current. It has a signal comparison circuit section, a time delay setting section that switches the time delay operation time value to an appropriate value and outputs a time delay signal corresponding to the time delay operation time value, and a plurality of switches. A switching unit that closes only one specific switch corresponding to the time delay operation time value of the time delay signal, When the comparison output signal is output from the ground fault signal comparison circuit section, charging of the capacitor element by the charging power supply is started, and the resistor element and the capacitor element are connected in series. The time delay signal generator that outputs the time delay signal, one input terminal to which the time delay signal is input, the other input terminal to which the reference voltage for the time delay signal is input, and the level of the time delay signal. A time delay signal comparison circuit section having an output terminal for outputting an operation signal when the value exceeds the reference voltage for the delay signal, and an operation section for releasing the main circuit contact when the operation signal is output. The time delay operation time can be changed by switching the charging condition for the capacitor element of the time delay signal generation section or the value of the reference voltage for the time delay signal based on the switch that is closed. Do not switch the value Earth leakage breaker, characterized in that. 4. The earth leakage breaker according to claim 3, wherein the switching unit inputs the A / D conversion unit for converting the time delay signal, which is an analog signal, into a binary signal, and the binary signal. A decoder that outputs a binary signal having the same number of bits as the number of switching stages of the time delay operation time value and a plurality of binary signals that are output from the decoder are input to each of them, and the binary signal corresponding to the level of the binary signal is input. An earth leakage circuit breaker having a switching element that turns on and off. 5. The earth leakage breaker according to claim 1, wherein the sensitivity setting unit and the time delay setting unit are a resistance element for setting a sensitivity current and a resistance element for setting a time delay operating time. And a setting ladder resistor that has one end grounded, and a changeover switch that switches the resistance element for setting the sensitivity current of the setting ladder resistor, and the time delay operation time of the setting ladder resistor. It is a setting section that is integrated with a changeover switch that switches the resistance element and a constant current source that is connected to the anti-ground side of the setting ladder resistance and supplies a constant value of direct current to the setting ladder resistance. A / D included in the variable resistance part excluding the parts and the switching part
The conversion unit consists of a conversion ladder resistor, a DC power supply that supplies a constant value of DC current or DC voltage to the conversion ladder resistor, and a setting ladder resistor and a constant current source that the setting unit has at the non-inverting input terminal. The DC voltage obtained at the connection point is commonly input, and the DC voltage obtained at the connection point between the different resistance elements that form the conversion ladder resistor is input to the inverting input terminal. A ground fault circuit breaker characterized in that a binary signal is output from each of the output terminals of a plurality of comparators.