GROUND-FAULT CIRCUIT INTERRUPTER

Abstract

 The present invention provides an earth leakage breaker, the detection sensitivity of which can be set from low sensitivity to high sensitivity by a mechanical setting in a simple configuration, and which can be forcibly set in high-speed operation. In an earth leakage breaker, when a sensitivity switch extension slide switch (171b) of a restriction setting portion (170) is manipulated and moved to set a sensitivity switch setting portion (120) to high sensitivity (30 mA), a protruding portion (171a) presses and moves a delay time switch extension slide switch (172b), whereby a delay time switch setting portion (150) is forcibly set to high-speed operation (delay time 0 ms).

Description

TECHNICAL FIELD

[0001] The present invention relates to an earth leakage breaker which performs overcurrent protection and ground fault current protection in low-voltage power distribution systems.

BACKGROUND ART

[0002] An earth leakage breaker has a function for breaking an AC circuit upon occurrence of leaks, and prevents the occurrence of accidents in AC circuits. Such an earth leakage breaker enables switching of the current sensitivity, which is the value of the leakage current at which the circuit breaking operation is performed, and switching of the time of delay time, which is a setting for the time of operation.
Such earth leakage breakers are broadly divided into domestic Japanese type earth leakage breakers, and foreign (European and American) type earth leakage breakers. First, a domestic Japanese type earth leakage breaker is explained, referring to the drawings. Fig. 7 shows the configuration of a conventional domestic type earth leakage breaker 10. The earth leakage breaker 10 comprises a zero-phase sequence current transformer 11; a sensitivity switch setting portion 12; a filter circuit 13; a leakage detection portion 14; a delay time switch setting portion 15; and a tripping driving portion 16.

[0003] An earth leakage breaker 10 with such a circuit configuration operates as follows.
In the zero-phase sequence current transformer 11, a main circuit conductor, not shown, penetrates the core 11a, and when a ground fault current arising from a ground fault or similar, or a leakage current arising from a leak (hereafter these currents are called unbalanced currents), are included in the load current flowing in the main circuit conductor, a secondary output current signal proportional to the unbalanced current is output from the output windings 11b thereof. This secondary output current signal is input to the sensitivity switch setting portion 12.

[0004] In the sensitivity switch setting portion 12, detectable secondary output current signals can be switched and set in stages, from low sensitivity to high sensitivity. Here, a setting switch, not shown, is used to switch the resistance connected across the output windings 11b. By thus changing the resistance value, the sensitivity is switched. The sensitivity can be set in a sensitivity switching range of 100 mA/300 mA/500 mA, so that switch settings from normal sensitivity (100 mA) to low sensitivity (500 mA) can be made. However, a high sensitivity described below (30 mA) cannot be set. The sensitivity switch setting portion 12 passes the secondary output current signal through the resistance with the value set by the sensitivity switch, and outputs a detection operation voltage signal.

[0005] The filter circuit 13 outputs a detection operation voltage signal obtained by eliminating noise components which may cause erroneous operation from the detection operation voltage signal output via the sensitivity switch setting portion 12. The detection operation voltage signal with noise components eliminated is output to the leakage detection portion 14.
The leakage detection portion 14 outputs a driving voltage signal when the voltage value of an input detection operation voltage signal exceeds a threshold value determined in advance. The driving voltage signal is output to the delay time switch setting portion 15.

[0006] The delay time switch setting portion 15 incorporates a delay time switch, not shown, which can switch and set a delay time; a plurality of charging resistors, which are switched according to the delay time switched and set by this delay time switch; and a charging circuit, which is charged with a charging current determined by these charging resistors. When a delay time is switched and set in advance by the delay time switch, a charging resistor is selected corresponding to this delay time and is connected to the charging circuit. When a driving voltage signal is input to the delay time switch setting portion 15, charging of the charging circuit is begun. At this time, the output from the charging circuit is not at a prescribed voltage for a charging interval equal to the delay time. After the delay time has elapsed from the beginning of charging of the charging circuit, the delay time switch setting portion 15 ends charging of the charging circuit, and outputs a driving voltage signal which has reached the prescribed voltage to the tripping driving portion 16.

[0007] When a driving voltage signal has been input, the tripping driving portion 16 drives an open/close mechanism for a contact of the main circuit, not shown, and opens the main circuit.
Such a domestic Japanese type earth leakage breaker 10 comprises a sensitivity switch setting portion 12 and delay time switch setting portion 15, and the sensitivity switch and delay time switch can each be set independently. In the domestic type conforming to JIS standards (JIS C 8371), it is stipulated that at high sensitivity (30 mA sensitivity), a non-delayed mode (high-speed operation mode) must be employed, with the object of protecting humans. In other words, an earth leakage breaker 10 for which the delay time can be set, cannot be switched and set to high sensitivity (30 mA sensitivity) with the object of protecting humans.

[0008] Next, a foreign (European and American) type earth leakage breaker is explained. A foreign (European and American) type earth leakage breaker combines a circuit breaker for wiring with an independent leakage protection unit with a separate structure. Such a foreign (European and American) type earth leakage breaker is explained referring to the drawings. Fig. 8 shows the configuration of a conventional foreign type earth leakage breaker. The earth leakage breaker 20 comprises a zero-phase sequence current transformer 21; a sensitivity switch setting portion 22; a filter circuit 23; a leakage detection portion 24; a delay time switch setting portion 25; and a tripping driving portion 26.

[0009] An earth leakage breaker 20 with such a circuit configuration operates as follows.
In the zero-phase sequence current transformer 21, a main circuit conductor, not shown, penetrates the core 21a, and when an unbalanced current is included in the load current flowing in the main circuit conductor, a secondary output current signal proportional to the unbalanced current is output from the output windings 21b thereof. This secondary output current signal is input to the sensitivity switch setting portion 22.

[0010] In the sensitivity switch setting portion 22, a setting switch, not shown, is used to switch the resistance connected across the output windings 21b. By thus changing the resistance value, the sensitivity can be switched and set in steps to sensitivities from high sensitivity to low sensitivity. The sensitivity switch setting portion 22 passes the secondary output current signal through the resistance with the value set by the sensitivity switch, and outputs a detection operation voltage signal. This sensitivity switch setting portion 22 comprises first and second circuits which perform sensitivity switching. The first circuit is a circuit to perform sensitivity switching from high sensitivity to low sensitivity; the second circuit is a circuit to perform high-speed operation when set to high sensitivity, and to perform delay time operation in other cases.

[0011] For example, the sensitivity switching range for the foreign type earth leakage breaker 20 shown in Fig. 8 is 30 mA/100 mA/300 mA/500 mA, and compared with the domestic type earth leakage breaker 10 shown in Fig. 7, switching and setting at a higher sensitivity (30 mA) is possible. Further, when switching to and setting the high sensitivity (30 mA) using the first circuit, high-speed operation is forcibly set by the second circuit, and this forced high-speed signal (arrow α in Fig. 8) circumvents the filter circuit 23 and leakage detection portion 24, and is directly output to the delay time switch setting portion 25. The operation of the delay time switch setting portion 25 in this case is described below.

[0012] To summarize, the sensitivity switch setting portion 22 outputs a forced high-speed signal (arrow α in Fig. 8) to the delay time switch setting portion 25 in the case of high sensitivity (30 mA), and in the case of another sensitivity (100 mA/300 mA/500 mA), outputs the detection operation voltage signal to the filter circuit 23.
The filter circuit 23 outputs a detection operation voltage signal obtained by eliminating noise components, which may cause erroneous operation, from the detection operation voltage signal output via the sensitivity switch setting portion 22. The detection operation voltage signal with noise components eliminated is output to the leakage detection portion 24.
The leakage detection portion 24 outputs a driving voltage signal when the voltage value of an input detection operation voltage signal exceeds a threshold value determined in advance. The driving voltage signal is output to the delay time switch setting portion 25.

[0013] The delay time switch setting portion 25 incorporates a delay time switch, not shown, which can switch and set a delay time; a plurality of charging resistors, which are switched according to the delay time switched and set by this delay time switch; and a charging circuit, which is charged with a charging current determined by these charging resistors. When a delay time is switched and set in advance by the delay time switch, a charging resistor is selected corresponding to this delay time and is connected to the charging circuit. When a driving voltage signal is input to the delay time switch setting portion 25, charging of the charging circuit is begun. At this time, the output from the charging circuit is not at a prescribed voltage for a charging interval equal to the delay time. After the delay time has elapsed from the beginning of charging of the charging circuit, the delay time switch setting portion 25 ends charging of the charging circuit, and outputs a driving voltage signal which has reached the prescribed voltage to the tripping driving portion 26. When the forced high-speed signal explained above is input to the delay time switch setting portion 25, a driving voltage signal is immediately output to the tripping driving portion 26.

[0014] When a driving voltage signal has been input, the tripping driving portion 26 drives an open/close mechanism for a contact of the main circuit, not shown, and opens the main circuit.
In this way, a foreign (European and American) type earth leakage breaker differs from a single-structure domestic type earth leakage breaker, in that switching to and setting of high sensitivity is possible in addition to switching to and setting of low sensitivity and normal sensitivity. And, when switching to and setting high sensitivity, high-speed operation is forcibly performed even in delay time switching. This is in conformance with standards (IEC947-2).

[0015] One example of such earth leakage breakers is for example the invention disclosed in Patent Reference 1 (title of the invention: Earth leakage breaker). In this technology, at the time of switching to and setting high sensitivity, a signal is output from the switch, and high-speed operation is forcibly switched to and set even in delay time switching.
Further, another example of an earth leakage breaker is the invention disclosed in Patent Reference 2 (title of the invention: Earth leakage breaker). In this technology, at the time of switching to and setting high sensitivity, a signal is output from a decoding circuit, and high-speed operation is forcibly switched to and set even in delay time switching.
Further, another example of an earth leakage breaker is the invention disclosed in Patent Reference 3 (title of the invention: Earth leakage breaker). In this technology, by means of a dial type switch setting, both sensitivity current switching and time limit switching are performed.

[0016] 

Patent Reference 1: Japanese Patent Application Laid-open No. 2005-327666 (paragraphs [0031] and [0032], Fig. 1 and Fig. 2)

Patent Reference 2: Japanese Patent Application Laid-open No. 2005-268097 (paragraph [0020], Fig. 1 and Fig. 2)

Patent Reference 3: Japanese Patent Application Laid-open No. H7-141979 (paragraphs [0011] and [0012], Fig. 2, Fig. 3 and Fig. 4)

[0017] The domestic type earth leakage breaker 10 of Fig. 7 above is a structure which integrally includes a sensitivity switch setting portion 12 and a delay time switch setting portion 15, but has not been configured to switch to and set high-speed operation simultaneously with switching to and setting of high sensitivity, as in foreign type devices.
Hence there has been a demand for an earth leakage breaker which, like the foreign type earth leakage breaker 20 of Fig. 8, enables selection of high-speed operation and delay time operation as well as enabling settings from high sensitivity to low sensitivity, and in which, when setting high sensitivity, forcibly switches to and sets high-speed operation as the delay time setting. However, in the foreign type earth leakage breaker 20 of Fig. 8, a forcible high-speed signal of small amplitude passes through the pattern wiring connecting the sensitivity switch setting portion 22 and the delay time switch setting portion 25. A signal with small amplitude is easily affected by noise, and so an anti-noise measure is necessary, and the wiring pattern becomes complicated.

[0018] In order to impart functions similar to those of a foreign type (European and American) earth leakage breaker, it is possible to provide a sensitivity switch setting portion for two circuits and a delay time switch setting portion for one circuit; but because a sensitivity switch setting portion for two circuits is extremely large, there has been the problem that the earth leakage breaker is increased in size. Hence a compact configuration such as in domestic type earth leakage breakers cannot be secured.
The earth leakage breaker of Patent Reference 1 sets high-speed operation by means of on/off judgment of a pushbutton high-speed switch, and uses electric signals, but cannot completely eliminate the influence of noise.

[0019] The earth leakage breaker of Patent Reference 2 makes settings using a logic decoding circuit, and uses electric signals, but cannot completely eliminate the influence of noise.
The earth leakage breaker of Patent Reference 3 enables selection of normal-speed operation and high-speed operation by mechanical setting means, but does not forcibly set the delay time setting to high-speed operation even when high sensitivity is set, and so a safety-related problem remains.

[0020] To summarize, there has been a demand for use of a mechanical configuration which is not affected by noise, and which enables sensitivity switching from high sensitivity to low sensitivity, and which enables delay time switching from high-speed operation to delay time operation. In particular, there has been a demand to employ a configuration comprising a single-circuit sensitivity switch setting portion and a single-circuit delay time switch setting portion which make earth leakage breakers mutually independent, and moreover to enable forcible delay time setting to high-speed operation simultaneously with switching to and setting of high sensitivity.
Hence this invention has as an object the provision of an earth leakage breaker in which, by means of mechanical settings with a simple configuration, high-speed operation is forcibly set simultaneously with setting the detection sensitivity from low sensitivity to high sensitivity.

[0021] In order to attain the above object, a first mode of an earth leakage breaker of this invention is characterized in comprising:

a zero-phase sequence current transformer, which outputs a secondary output current signal proportional to the unbalanced current included in a load current of a penetrating main circuit conductor;

a sensitivity switch setting portion, in which sensitivity is switched in a plurality of stages from high sensitivity to low sensitivity, and which passes the secondary output current signal at a resistance set by sensitivity switching to cause a detection operation voltage signal to be output;

a filter circuit, which outputs a detection operation voltage signal obtained by eliminating noise components from the detection operation voltage signal output from the sensitivity switch setting portion;

a leakage detection portion, which, when a voltage value of the detection operation voltage signal from which noise components have been eliminated exceeds a predetermined threshold value, outputs a driving voltage signal;

a delay time switch setting portion, which performs delay time switching in a plurality of stages from high-speed operation to delay time operation, and during high-speed operation, outputs a driving voltage signal immediately after input of the driving voltage signal, and during delay time operation outputs the driving voltage signal after a preset delay time has elapsed from input of the driving voltage signal;

a tripping driving portion, which, when the driving voltage signal has been input, drives an open/close mechanism of a main circuit contact, and opens the main circuit; and

a restriction setting portion, which causes the sensitivity switching of the sensitivity switch setting portion and the delay time switching of the delay time switch setting portion to be mechanically linked, and by restricting a delay time switching range of delay time switching of the delay time switch setting portion according to the sensitivity switching of the sensitivity switch setting portion, determines settable operation speeds for a sensitivity, and when the sensitivity switch setting portion sets a high sensitivity, restricts the delay time switch setting portion to only high-speed operation.

[0022] Further, a second mode is characterized in that the restriction setting portion comprises:

a sensitivity switch extension setting portion, which has a sensitivity switching extension slide switch, connected to a sensitivity switching slide switch of the sensitivity switch setting portion and moving this sensitivity switching slide switch;

a delay time switching extension setting portion, which has a delay time switching extension slide switch, connected to a delay time switching slide switch of the delay time switch setting portion and moving this delay time switching slide switch; and

a protruding portion, which is mechanically connected to the sensitivity switching extension slide switch and one portion of which is positioned on a line of action of the delay time switching extension slide switch, and moreover which, by means of movement according to movement of the sensitivity switching extension slide switch, presses the delay time switching extension slide switch, or restricts the movement of the delay time switching extension slide switch.

DISCLOSURE OF THE INVENTION

[0023] By means of this invention, an earth leakage breaker can be provided in which detection sensitivity can be set from low sensitivity to high sensitivity by means of a mechanical setting with a simple configuration, and high-speed operation is simultaneously forcibly set.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 

Fig. 1 shows the configuration of the earth leakage breaker of an embodiment of the invention;

Fig. 2 explains the restriction setting portion of the earth leakage breaker of an embodiment of the invention;

Fig. 3 explains a sensitivity switching extension setting portion and a delay time switching extension setting portion;

Fig. 4 explains a sensitivity switching extension setting portion and a delay time switching extension setting portion;

Fig. 5A explains the positions of a sensitivity switching extension slide switch and delay time switching extension slide switch in restriction of settings by a restriction setting portion, and Fig. 5B explains positions of a sensitivity switch and delay time switch in restriction of settings by a restriction setting portion;

Fig. 6A explains the positions of a sensitivity switching extension slide switch and delay time switching extension slide switch in restriction of settings by a restriction setting portion, and Fig. 6B explains positions of a sensitivity switch and delay time switch in restriction of settings by a restriction setting portion;

Fig. 7 shows the configuration of a conventional domestic type earth leakage breaker; and

Fig. 8 shows the configuration of a conventional foreign type earth leakage breaker.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] An embodiment of the invention is explained referring to Fig. 1 to Fig. 6. As shown in Fig. 1, an earth leakage breaker 100 comprises a zero-phase sequence current transformer 110; a sensitivity switch setting portion 120; a filter circuit 130; a leakage detection portion 140; a delay time switch setting portion 150; a tripping driving portion 160; and a restriction setting portion 170. The earth leakage breaker 100 of this embodiment also has features which are redundant with the prior art, but to facilitate explanation these are explained once again.
The earth leakage breaker 100 with this circuit configuration operates as follows.
In the zero-phase sequence current transformer 110, a main circuit conductor, not shown, penetrates a core 110a; when the load current flowing in the main circuit conductor includes an unbalanced current, a secondary output current signal proportional to the unbalanced current is output from the output windings 110b. This secondary output current signal is input to the sensitivity switch setting portion 120.

[0026] The sensitivity switch setting portion 120 comprises a sensitivity switching slide switch 121 (see Fig. 3) which performs switching and setting of the sensitivity. The sensitivity switching slide switch 121 is linked with the restriction setting portion 170. The sensitivity switch setting portion 120 is configured so as to enable changing of resistance values by switching the resistor connected across the output windings 110b by means of the sensitivity switching slide switch 121, to switch and set the sensitivity in stages from high sensitivity to low sensitivity. And, the sensitivity switch setting portion 120 passes the secondary output current signal through the switched and set resistor and outputs a detection operation voltage signal. The sensitivity switching range over which this sensitivity switch setting portion 120 can switch the sensitivity is set to 30 mA/100 mA/300 mA/500 mA.

[0027] The filter circuit 130 outputs a detection operation voltage signal obtained by eliminating noise components, which can cause erroneous operation, from the detection operation voltage signal output via the sensitivity switch setting portion 120. The detection operation voltage signal with noise components eliminated is output to the leakage detection portion 140.
When the voltage value of the input detection operation voltage signal exceeds a threshold value determined in advance, the leakage detection portion 140 outputs a driving voltage signal. This driving voltage signal is output to the delay time switch setting portion 150.

[0028] The delay time switch setting portion 150 incorporates a delay time switching slide switch 151 (see Fig. 3); a plurality of charging resistors; and a charging circuit (as a specific example, a capacitor). The delay time switching slide switch 151 enables switching and setting of the delay time. The plurality of charging resistors are switched according to the delay time set by the delay time switching slide switch 151. The charging circuit is charged by the charging current decided by the selected charging resistor. In the delay time switch setting portion 150, when a delay time is switched and set in advance by the delay time switching slide switch 151, the charging resistor corresponding to the delay time is selected and is connected to the charging circuit. In the delay time operation, when a driving voltage signal is input to the delay time switch setting portion 150, charging of the charging circuit is begun. At this time, the output from the charging circuit is not at a prescribed voltage for a charging interval equal to the delay time. After the delay time has elapsed from the beginning of charging of the charging circuit, the delay time switch setting portion 150 ends charging of the charging circuit, and the driving voltage signal which has reached the prescribed voltage is output to the tripping driving portion 160. In addition, the delay time switch setting portion 150 comprises a high-speed conduction portion which directly connects the leakage detection portion 140 and the tripping driving portion 160, and selects the high-speed conduction portion during high-speed operation, described below.

[0029] When a delay operation or high-speed operation driving voltage signal is input, the tripping driving portion 160 drives the open/close mechanism of the main circuit contact, not shown, and opens the main circuit.
The restriction setting portion 170 mechanically links the sensitivity switching of the sensitivity switch setting portion 120 and the delay time switching of the delay time switch setting portion 150, and by restricting the delay time switching range during delay time switching of the delay time switch setting portion 150 according to the sensitivity switching of the sensitivity switch setting portion 120, decides the operation speeds which can be set for the sensitivity. And, when the sensitivity switch setting portion 120 is set to high sensitivity, the restriction setting portion 170 sets and restricts the delay time switch setting portion 150 to high-speed operation only. The dashed-line arrows A and B in Fig. 1 indicate that the restriction setting portion 170 mechanically restricts the sensitivity switch setting portion 120 and the delay time switch setting portion 150.

[0030] In this earth leakage breaker 100, the sensitivity can be set in the stages 30 mA/100 mA/300 mA/500 mA by the sensitivity switch setting portion 120, and moreover the delay time can be set in the stages 0 ms/200 ms/500 ms/1000 ms by the delay time switch setting portion 150. And, as a characteristic of the earth leakage breaker 100, a restriction setting portion 170 is provided which mechanically links and manipulates the sensitivity switch setting portion 120 and the delay time switch setting portion 150, so that high-speed operation (0 ms) is set mechanically by the delay time switch setting portion 150, in particular when the sensitivity switch setting portion 120 executes setting at a high sensitivity (30mA).

[0031] Next, the mechanical structures of the sensitivity switch setting portion 120, delay time switch setting portion 150, and restriction setting portion 170 are explained in detail. As shown in Fig. 2 to Fig. 4, settings of the sensitivity switch setting portion 120 and delay time switch setting portion 150 are restricted by the mechanically linked structure of the restriction setting portion 170. The sensitivity switch setting portion 120 comprises a sensitivity switching slide switch 121. The delay time switch setting portion 150 comprises a delay time switching slide switch 151. The sensitivity switch setting portion 120 and delay time switch setting portion 150 are fixed on a printed board 180 and are electrically connected by a wiring pattern. The restriction setting portion 170 further comprises a sensitivity switch extension setting portion 171 and a delay time switch extension setting portion 172.

[0032] As shown in Fig. 3, above the sensitivity switch setting portion 120 is mounted the sensitivity switch extension setting portion 171. The mounted state is as shown in Fig. 4. The sensitivity switch extension setting portion 171 comprises a protruding portion 171a; a sensitivity switch extension slide switch 171b; and a sensitivity switch intermediate adapter 171c. Specifically, the sensitivity switch extension slide switch 171b is mounted, via a linking mechanism within the sensitivity switch intermediate adapter 171c, onto the sensitivity switching slide switch 121. And, when the sensitivity switch extension slide switch 171b is moved in the direction of arrow a (or in the direction of arrow b) in Fig. 3, the sensitivity switching slide switch 121 of the sensitivity switch setting portion 120 also moves in the direction of arrow a (or in the direction of arrow b) via the linking mechanism within the sensitivity switch intermediate adapter 171c.

[0033] Further, as shown in Fig. 3, the delay time switch extension setting portion 172 is mounted above the delay time switch setting portion 150. The mounted state is as shown in Fig. 4. The delay time switch extension setting portion 172 comprises an abutting portion 172a; a delay time switch extension slide switch 172b; and a delay time switch intermediate adapter 172c. Specifically, the delay time switch extension slide switch 172b is mounted, via a linking mechanism within the delay time switch intermediate adapter 172c, onto the delay time switching slide switch 151. And, when the delay time switch extension slide switch 172b is moved in the direction of arrow a (or in the direction of arrow b) in Fig. 3, the delay time switching slide switch 151 of the delay time switch setting portion 150 also moves in the direction of arrow a (or in the direction of arrow b) in Fig. 3, via the linking mechanism within the delay time switch intermediate adapter 172c.

[0034] And, the protruding portion 171a is provided protruding from the sensitivity switch extension slide switch 171b. The protruding portion 171a is mechanically connected to the sensitivity switch extension slide switch 171b, a portion thereof is positioned on the line of action of the delay time switch extension slide switch 172b, and moves together with movement in the direction of arrow a of the sensitivity switch extension slide switch 171b, to abut the abutting portion 172a of the delay time switch extension slide switch 172b. Further, when the sensitivity switch extension slide switch 171b is moved in the direction of arrow a, together with movement of the sensitivity switch extension slide switch 171b, the protruding portion 171a moves the delay time switch extension slide switch 172b.

[0035] By means of this restriction setting portion 170, the settings of the sensitivity switch setting portion 120 and the delay time switch setting portion 150 are restricted. Specifically, as shown in Fig. 5A, when the sensitivity switch extension slide switch 171b is at the lowest sensitivity (500 mA, on the bottom in Fig. 5A and Fig. 5B), the protruding portion 171a is also at the lowest position, so that the delay time switch extension slide switch 172b is not restricted, and can move in the direction of the arrow c, and the desired delay time (0 ms/200 ms/500 ms/1000 ms) can be selected.

[0036] And, during high-speed operation (0 ms), the high-speed conduction portion is selected by the delay time switch setting portion 150, and the leakage detection portion 140 and tripping driving portion 160 are directly connected. At this time the delay time switch setting portion 150 outputs the driving voltage signal to the tripping driving portion 160. In this way, circuit breaking is performed by high-speed operation.
Further, during delay time operation (200 ms/500 ms/1000 ms), a path is selected by the delay time switch setting portion 150 passing through a charging resistor and the charging circuit. The driving voltage signal output from the leakage detection portion 140 is applied to the charging resistor, a charging current is output, and when this charging current is input to the charging circuit, charging of the charging circuit is begun. The delay time switch setting portion 150 ends charging of the charging circuit after the delay time has elapsed from the start of charging of the charging circuit, and the driving voltage signal, which has reached a prescribed voltage, is output to the tripping driving portion 160. In this way, circuit breaking is performed with delay time operation.

[0037] On the other hand, as shown in Fig. 6A, when the sensitivity switch extension slide switch 171b is moved in the direction of arrow d and is at the highest sensitivity (30 mA, the top in Fig. 6A and Fig. 6B), the protruding portion 171a also moves in the direction of the arrow d and abuts the abutting portion 172a of the delay time switch extension slide switch 172b, moving the delay time switch extension slide switch 172b. At this time, the delay time switch extension slide switch 172b is restricted to the highest delay time (0 ms), and is forcibly set to high-speed operation.

[0038] In this case, the fastest conducting portion is selected within the delay time switch setting portion 150. Hence the driving voltage signal output from the leakage detection portion 140 is input without modification to the tripping driving portion 160. By this means, high-speed operation is realized.
In this setting example, actual settings are as shown in Table 1 below. In Table 1, a correspondence table between setting positions of the sensitivity switching slide switch 121 and the delay time switching slide switch 151 (which is also a correspondence table between setting positions of the sensitivity switch extension slide switch 171b and the delay time switch extension slide switch 172b) is shown.

[0039] Table 1

Setting position of sensitivity switching slide switch (mA)	Setting position of delay time switching slide switch (ms)
	0 (high speed)	200	500	1000
30	O	×	×	×
100	O	O	×	×
200	O	O	O	×
500	O	O	O	O

[0040] For example, when using the sensitivity switching slide switch 121 the low sensitivity of 500 mA is set, all the delay times, 0 ms, 200 ms, 500 ms, and 1000 ms, can be set by the delay time switching slide switch 151. And, when the normal sensitivity of 100 mA is set using the sensitivity switching slide switch 121, the two delay times of 0 ms and 200 ms can be set by the delay time switching slide switch 151. That is, to the extent that the sensitivity switching slide switch 121 moves, the delay time switching slide switch 151 can be moved. And, when the sensitivity switching slide switch 121 is used to set the high sensitivity of 30 mA, the delay time switching slide switch 151 can set only high-speed operation with a delay time of 0 ms.

[0041] In the above, the earth leakage breaker 100 of an embodiment of the invention has been explained. By adopting this configuration, the sensitivity switch setting portion 120 is a switch employing a single circuit, so that compared with a sensitivity switch setting portion employing a dual-circuit switch of the prior art, compactness and low cost are realized. Further, setting is performed only by mechanical means, so that a pattern connecting the sensitivity switch setting portion 120 and delay time switch setting portion 150 is eliminated, and the wiring pattern is reduced and simplified.
Further, with all circuits using the filter circuit 130 and leakage detection portion 140, in this respect a wiring pattern can be eliminated.
By means of this embodiment of the invention, an earth leakage breaker can be provided which enables setting of the detection sensitivity from low sensitivity to high sensitivity, and which forcibly sets high-speed operation by a mechanical operation.

INDUSTRIAL APPLICABILITY

[0042] This invention can be applied as an earth leakage breaker which realizes overcurrent protection functions and ground-fault current protection functions in low-voltage wiring systems in particular.

EXPLANATION OF REFERENCE NUMERALS

[0043] 

100

Earth leakage breaker

110

Zero-phase sequence current transformer

110a

Core

110b

Output windings

120

Sensitivity switch setting portion

121

Sensitivity switching slide switch

130

Filter circuit

140

Leakage detection portion

150

Delay time switch setting portion

151

Delay time switching slide switch

160

Tripping driving portion

170

Restriction setting portion

171

Sensitivity switch extension setting portion

171a

Protruding portion

171b

Sensitivity switch extension slide switch

171c

Sensitivity switch intermediate adapter

172

Delay time switch extension setting portion

172a

Abutting portion

172b

Delay time switch extension slide switch

172c

Delay time switch intermediate adapter

180

Printed board

A, B

Mechanical restriction

Claims

1. An earth leakage breaker, comprising:

a zero-phase sequence current transformer, which outputs a secondary output current signal proportional to the unbalanced current included in a load current of a penetrating main circuit conductor;

a sensitivity switch setting portion, in which sensitivity is switched in a plurality of stages from high sensitivity to low sensitivity, and which passes the secondary output current signal at a resistance set by sensitivity switching to cause a detection operation voltage signal to be output;

a filter circuit, which outputs a detection operation voltage signal obtained by eliminating noise components from the detection operation voltage signal output from the sensitivity switch setting portion;

a leakage detection portion, which, when a voltage value of the detection operation voltage signal from which noise components have been eliminated exceeds a predetermined threshold value, outputs a driving voltage signal;

a delay time switch setting portion, which performs delay time switching in a plurality of stages from high-speed operation to delay time operation, and during high-speed operation, outputs a driving voltage signal immediately after input of the driving voltage signal, and during delay time operation outputs the driving voltage signal after a preset delay time has elapsed from input of the driving voltage signal;

a tripping driving portion, which, when the driving voltage signal has been input, drives an open/close mechanism of a main circuit contact, and opens the main circuit; and

a restriction setting portion, which causes the sensitivity switching of the sensitivity switch setting portion and the delay time switching of the delay time switch setting portion to be mechanically linked, and by restricting a delay time switching range of delay time switching of the delay time switch setting portion according to the sensitivity switching of the sensitivity switch setting portion, determines settable operation speeds for a sensitivity, and when the sensitivity switch setting portion sets a high sensitivity, restricts the delay time switch setting portion to only high-speed operation.

2. The earth leakage breaker according to Claim 1, characterized in that the restriction setting portion comprises:

a sensitivity switch extension setting portion, which has a sensitivity switching extension slide switch, connected to a sensitivity switching slide switch of the sensitivity switch setting portion and moving this sensitivity switching slide switch;

a delay time switching extension setting portion, which has a delay time switching extension slide switch, connected to a delay time switching slide switch of the delay time switch setting portion and moving this delay time switching slide switch; and

a protruding portion, which is mechanically connected to the sensitivity switching extension slide switch and one portion of which is positioned on a line of action of the delay time switching extension slide switch, and moreover which, by means of movement according to movement of the sensitivity switching extension slide switch, presses the delay time switching extension slide switch, or restricts the movement of the delay time switching extension slide switch.

Drawing