DE102004056976A1 - Residual-current device - Google Patents

Abstract

A power supply circuit having a constant current circuit which converts an AC power supplied from a main power circuit to a DC power so as to supply a constant DC power to a fault current detection circuit is used as a power supply circuit for supplying power to a fault current detection circuit of the residual current operated circuit breaker. The circuit used to connect the main circuit to an AC input of this constant current circuit includes a series connected test resistor element, and both ends of this resistor element are connected through a test switch to a test winding of a zero phase current transformer, thereby providing the residual current test circuit.

Description

The The invention relates to a residual current circuit breaker for detecting from earth faults, in with an electric motor and various other consumers associated power distribution systems may occur in relation to it standing accidents to avoid, and in particular relates to an improvement of the test circuit.

To accurately perform a functional test in a residual current circuit breaker, various device configurations have conventionally been used for a ground fault test circuit of a residual current circuit breaker. Such a configuration is explained in JP 2002-78187 A. 7 shows the structure of the shown in this illustrated residual current circuit breaker.

The in 7 shown fault current circuit breaker has several rated voltages (ie, three rated voltages of 100 V, 200 V and 400 V). The fault current circuit breaker shown in the drawing 1 has a power source side terminal 3A and a load-side terminal 3B on. These terminals 3A and 3B are connected to a main circuit in which an opening / closing member 8th are provided with a plurality of poles for turning on or off the load current. The opening / closing member 8th and the load-side terminal 3B are via main circuit conductors 2 connected by a zero-phase current transformer 5 passed through. The zero-phase current transformer 5 detects a fault current in one with the load-side terminal 3B connected load circuit. A fault current detection circuit 6 judged based on an output current of the fault current detection winding 51 of the zero-phase current transformer 5 the presence of a ground fault and then sends upon detection of a fault current, a drive signal to the triggering device 7 , Upon receipt of the drive signal from the fault current detection circuit 6 switches the triggering device 7 a (not shown) switching lock of the opening / closing member 8th which opens a contact point of the opening / closing member to interrupt the load circuit. The fault current detection circuit 6 is from the main circuit 2 via a power supply circuit 4 powered.

A test circuit 9 includes: a test switch 91 which, when carrying out a functional test, closes a test circuit in the main circuit 2 a test current of a test winding 52 a zero-phase current transformer 5 supply; three boundary resistance elements 921 to 923 for limiting the test current; and a selector switch 93 to make a selection of these three resistive elements.

When the test current in the test circuit 9 is held constant, even if the rated voltage changes between 100 V and 400 V, then the fault current detection circuit 6 have a constant detection sensitivity for the residual current function test, which enables the residual current function test to be carried out more accurately and with greater reliability. Therefore, this residual current circuit breaker with current limiting resistor elements 921 . 922 and 923 which have resistance values corresponding to the rated voltages of 100 V, 200 V and 400 V, so that even if the rated voltage changes, the test current, which is the test winding 52 is fed, remains constant. This residual current circuit breaker is configured such that, depending on the rated voltage used, one of the current limiting resistance elements 921 to 923 using the selector switch 93 can be selected.

The test circle 9 can be from a test switch 91 and a single current limiting resistor element 923 exist, which limits the test current. The test switch 91 Closes the test circuit during a functional test and leads from the main circuit 2 a test current of a test winding 52 of the zero-phase current transformer 5 to.

A test current detected by a zero-phase current transformer is less than two and a half times a rated nominal current at rated voltage. For a circuit breaker with two or more rated voltages or a sensitivity selection function, it is necessary for the test current to be less than two and a half times the largest nominal response current at the lowest rated voltage. For example, if the rated voltage that can be applied is 100 to 400 V and the selectable nominal response current is 100/200/500 mA, the number of turns of the test windings and the value of the current limiting resistor element are 923 set so that a test current of less than 2.5 times the rated response current of 500 mA flows at a rated voltage of 100V.

In a fault current circuit breaker including the former test circuit, even if the rated voltage is changed from 100 V to 400 V, the corresponding resistance element based on the rated voltage can be operated by operating the selector switch 93 be selected to the test winding 52 of the zero-phase current transformer 5 with a constant test current from the test circuit 9 to supply. As a result, the functional test can be performed accurately and stably.

however For example, the conventional device described above requires the number of current limiting resistor elements and the selector switch corresponds to the type of nominal voltage to be used, whereby problems such as an increased space requirement of the test circuit and an increase The number of components caused, in turn, among other things increased Production costs result.

One Another problem is due to the fact that when open test switch always a high voltage between the contact points is applied (in particular when the rated voltage is high), which increases the distance of the contact points this test switch required, whereby the switch is increased.

at a ground fault circuit breaker having the latter test circuit, when the rated operating voltage is high, that across the current limiting resistor element applied voltage during the test operation large, whereby the power consumption is increased.

Out This reason conventionally becomes using single current limiting resistor element with large wattage capacity, or the electrical energy intake is by a majority in series split current limiting resistors divided.

As a result, the problem arises that of installing a test circuit needed Room gets bigger, and due to the increase The number of components increases the production costs.

Around to solve these problems It is an object of the invention to provide a residual current circuit breaker to provide a small test circuit, which requires less space and with the achieved a residual current function test in a precise manner can be.

The The task described above can with a residual current circuit breaker according to claims 1, 5 and 6 solved become. Advantageous developments are the subject of the dependent claims.

With a structure of the residual current circuit breaker according to claim 4, the Terminal voltage of the test resistor element be limited.

The Power supply circuit of the invention includes a constant current circuit, and consequently flows in a test resistor element, the at the AC input of the power supply circuit in series switched inserted is, independent on the size of the rated voltage a constant stream. Thus, the voltage is constant at both ends, and at a functional test, independently of the size of the rated voltage, one test winding of the zero phase current transformer from both ends of the test resistor element supplied with a constant voltage, and it becomes a constant test current fed. Made possible in this way the invention by using a single Prüfwiderstandselementes that the zero-phase current transformer independently on the size of the rated voltage a constant test current supplied becomes. As a result, a residual current protection function check in carried out accurately and reducing the number of test resistor elements to be used the effect that the space requirement of the test circuit is reduced. The abutting the test resistor element Voltage can be reduced by providing a resistance value for the test resistor element selected which is smaller than the internal impedance of the constant current circuit, whereby when opened test switch the voltage between the contact points is reduced, which is a Reducing the distance of the contact points allows and provides the effect that this switch is downsized.

If the leakage current detection circuit the sensitivity adjustment circuit for setting the detection sensitivity or the response setting circuit for setting the operation or response time is by means of a coupling with the test switch means intended to be independent from the setting of the sensitivity setting circuit or the Response setting to set a predetermined sensitivity or response time. This makes possible, that the fault current detection circuit in a residual current function test a has constant detection sensitivity or response time, whereby an accurate and stable performance of a functional test is made possible.

preferred embodiments The invention will be described below with reference to the accompanying drawings explained in more detail; it demonstrate:

1 the structure of the residual current circuit breaker according to a first embodiment of the invention;

2 especially the power supply scarf device of the residual current circuit breaker;

3 the functioning of in 2 illustrated power supply circuit;

4 the structure of a second embodiment of the invention;

5 the construction of a third embodiment of the invention;

6 the construction of a fourth embodiment of the invention;

7 the structure of a conventional residual current circuit breaker.

First embodiment

1 shows the structure of a first embodiment of the invention.

In 1 denotes reference numeral 1 a residual current circuit breaker in which all components are encapsulated in a housing made of insulating material. This residual current circuit breaker 1 includes: the main circuit 2 , which the power source side terminals 3A with the load-side terminals 3B links; the opening / closing member 8th to open or close this main circuit; the zero-phase current transformer 5 through which the conductors of all phases of the main circuit 2 passed through and detects a fault current in the main circuit; the fault current detection circuit 6 indicating the sense current in the fault current sense winding 51 this zero-phase current transformer 5 monitored to detect the presence of a ground fault; the triggering device 7 based on one of this fault current detection circuit 6 sent, an earth fault indicating output signal of the switching lock of the opening / closing member 8th turns off, which is the opening / closing member 8th interrupts; and the power supply circuit 4 which electrical current for the operation of the fault current detection circuit 6 supplies.

The power supply circuit 4 includes: a rectifier circuit 41 which one of the main circuit 2 supplied alternating current to a direct current, and a constant current circuit, which controls the output current of the rectifier circuit 41 so controls that the output current is a predetermined constant current. In this power supply circuit 4 is the main circuit 2 connected to an AC input, which is in series with the test resistor element 11 is switched. Both ends of the test resistor element 11 are over the test switch 12 with the in zero-phase current transformer 5 provided test winding 52 connected in series. The test resistor element 11 , the test switch 12 and the test winding 52 form a test circle 10 ,

2 shows in more detail the structure of the constant current circuit 42 the power supply circuit 4 ,

According to 2 includes the constant current circuit 42 a transistor Tr ₁ , whose collector is connected to the output of the rectifier circuit 41 is connected, whose emitter is connected via a resistor r ₂ to a load circuit, and in which a resistor r _{1 is connected} between the collector and base. Further, a transistor Tr _{2 is} provided, whose emitter-collector circuit is connected between the base and emitter of the transistor Tr ₁ and in which a resistor r _{3 is connected} between emitter and base. A constant voltage diode ZD ₁ is connected between the base of the transistor Tr ₂ and the load-circuit side end of the resistor r ₂ to the constant-current circuit 42 to build. The transistor Tr ₂ differs from the transistor Tr ₁ in that the resistance r ₁ is set to be equal to or greater than 100 kΩ, so that the voltage (voltage drop) between the emitter and the collector is reduced, and a low power capacity element can be used. The value of the resistor r ₃ is also in the two-digit kΩ range and is chosen so that it is sufficiently larger than the forward resistance value (about 100 Ω) between the emitter and collector of the transistor Tr ₂ . Thus, the current flowing through the resistor r ₃ and the constant voltage diode ZD ₁ to the load circuit is sufficiently small and negligible.

In addition to the current limiting resistor r ₂ , the second transistor Tr _{2 is} present, so that a current 1b flowing to the base side of the first transistor Tr ₁ flows to it, and as a result, the current changes 1b proportional to the DC voltage V _i , as in 3 shown. The reason for this is that the base potential of the transistor Tr ₂ is kept at a constant level by the constant-voltage diode ZD ₁ .

As described above, the current changes 1b proportional to the change of the DC voltage V _i , and consequently the voltage drop across the resistor r ₁ decreases in accordance with the increase of the current 1b to, and thus the base potential of the transistor Tr ₁ decreases approximately linearly to this voltage V _i . Thus, the emitter current I _{e of} the transistor Tr ₁ decreases approximately linearly to change the DC voltage V _i , as in 3 shown.

As described above, the currents I _e and I _b depending on a change in the input voltage V _i a complementary change, and Consequently, the current I, which is the fault current detection circuit 6 of the load circuit is supplied (sum of I _e and I _b ), regardless of the change in the input voltage V _i constant.

As described above, the power supply circuit includes 4 the constant current circuit 42 , and consequently the fault current detection circuit 6 a constant current can be supplied even if the rated voltage used changes, and the input alternating current can also be constant. This allows the voltage at both ends of the test resistor element 11 regardless of a change in the voltage of the main circuit 2 can be kept at a constant level.

When the test switch 12 of the test circle 10 in the 1 and 2 is turned on for a residual current function test, which is at both ends of the test resistor element 11 applied voltage of the test winding 52 of the zero-phase current transformer 5 supplied, and the test current (which is determined by the magnitude of this voltage) flows into this test winding 52 , The at both ends of the test resistor element 11 applied voltage remains regardless of the size of the voltage of the main circuit 2 constant, due to the function of the constant current circuit 42 , and therefore is constant even if the nominal voltage used is changed. As a result, the test current (simulated fault current), which is the test winding of the zero-phase current transformer, remains 5 regardless of the rated voltage used, constant, which allows the functional test of the fault current detection circuit 6 accurately and with greater reliability.

In this embodiment, when the selected resistance of the test resistor element 11 sufficiently smaller than the internal impedance of the power supply circuit 4 that is at the test resistor element 11 applied voltage can be reduced to a value of a few volts, even if the rated voltage of the main circuit 2 is large (eg 400 V), and consequently, the between the contact points of the test switch 12 reduces applied voltage, the distance between the contact points of this switch can be reduced and this switch can be of smaller size.

In addition, there is the fault current detection circuit 6 from an electronic circuit and therefore has an operating current in the order of a few mA, and consequently, the power supply circuit 4 also have a rated output current of the order of a few mA, a resistive element of small rated thermal capacity can be used as the test resistor element connected in series with this power supply circuit, and the test circuit can be made smaller.

Second embodiment

4 shows the structure of the second embodiment of the invention.

The second embodiment has the same structure as the first embodiment, except that the phases on the AC input side of the rectifier circuit 41 the power supply circuit 4 the input resistors R ₁ , R ₂ and R _{3 are} inserted.

When the input resistors R ₁ , R ₂ and R _{3 are} inserted in the power supply circuit as described above, these resistance elements together with the smoothing capacitor C _{1 form} in the power supply circuit 4 (please refer 2 ), a filter circuit which allows the absorption of relatively high frequency voltage spikes, and thus the power supply circuit 4 and the test switch 12 of the test circle 10 resist a larger surge.

Third embodiment

5 shows the construction of the third embodiment of the invention.

In the third embodiment of 5 are both ends of the test resistor element 11 is connected to two constant-voltage diodes ZD ₃ and ZD ₄ connected in series and the terminal voltage of the test resistor element 11 is limited to a value that is less than or equal to the constant voltage set by the constant voltage diodes. The constant voltage diodes allow the voltage applied to both ends to be limited to a value less than or equal to a constant value, even if the resistance of the test resistor element 11 was not scaled down, thereby allowing that the test switch 12 supplied AC voltage is reduced. Therefore, the distance between the contact points can be reduced and thus the switch can be downsized.

Fourth embodiment

6 shows a fourth embodiment of the invention.

In 6 denotes reference numeral 61 a detection sensitivity setting circuit of the leakage current detection circuit 6 consisting of a selector switch or the like. By operation NEN this setting circuit 61 may be one of several sensitivity values included in the fault current detection circuit 6 are predetermined, selected and set.

reference numeral 62 denotes a sensitivity adjustment switch to the adjustment circuit 61 according to the invention, to be able to disconnect from the fault current detecting circuit so that a predetermined sensitivity regardless of the setting of the sensitivity setting circuit 61 the fault current detection circuit 6 can be adjusted. This switch 62 is with the test switch 12 of the test circle 10 coupled, and its operation is such that it is turned off when the test switch 12 is turned on.

When the test switch 12 is switched on, the residual current function test of the residual current circuit breaker 1 will perform the switch 62 turned off, and the sensitivity adjustment circuit 61 is from the fault current detection circuit 6 disconnected, thereby allowing the fault current detection circuit 6 has a sensitivity corresponding to the test current (simulated fault current), which of the test circuit 10 the test winding 52 of the zero-phase current transformer 5 is set to a predetermined sensitivity is set. This enables accurate execution of the residual current functional test, since even a residual current circuit breaker having a fault current detecting circuit with a sensitivity adjusting circuit enables a residual current functional test in which the detection sensitivity for the fault current detecting circuit 6 always constant.

The fault current detection circuit 6 of the residual current circuit breaker 1 from 6 further includes a response setting circuit 63 for setting a response delay or response time (that is, a delay from the time of detecting a ground fault to the time of generating an output signal). This response setting circuit 63 is provided to prevent an erroneous response caused by a short-term intrusion of a pulse-like noise signal or the like. At the response setting circuit 63 Switching and setting the response time by means of a selector switch in accordance with the Störimpulstyp, for which one wants to prevent an erroneous triggering takes place. In addition, the response setting circuit is 63 provided to set a predetermined response time for protection against unnecessary response, or to achieve a protective cooperation with the device behind it. When the response setting circuit 63 determines the response time, can perform no accurate performance of the residual current function test, unless in the functional test is the operation of the test switch 12 in accordance with this response time, and thus, when performing the test, the response setting circuit must 63 set time in advance. In order to improve on this point, the response setting circuit becomes 63 is disconnected from the fault current detection circuit according to the invention and is provided with a response time setting switch 64 which can be used to independently of the setting of the Ansprech-setting circuit 63 to set a predetermined response time. This switch 64 is designed to be with the test switch 12 of the test circle 10 so coupled is that turning off the switch 64 takes place when this test switch 12 is turned on.

The structure described above allows, if for carrying out a residual current function test of the test switch 12 is turned on, the response time setting switch 64 is turned off, the Ansprech-setting circuit 63 from the fault current detection circuit 6 is disconnected and the response time is set to a predetermined time. As a result, a residual current function test can always be performed with a constant response time, allowing accurate performance of the functional test.

Claims (6)

Residual current circuit breaker, comprising: an opening / closing device ( 8th ) for opening or closing a main circuit ( 2 ), a zero-phase current transformer ( 5 ), through the conductor of all phases of the main circuit ( 2 ) are passed; a fault current detection circuit ( 6 ) based on an output current of a fault current detection winding ( 51 ) of the zero-phase current transformer ( 5 ) the presence of a ground fault is detectable; a triggering device ( 7 ) based on one of the fault current detection circuit ( 6 ) output signal representing the presence of a ground fault, the opening / closing means for opening the main circuit is switched off; a power supply circuit ( 4 ), which of the fault current detection circuit ( 6 ) supplies electrical power; and a test circuit ( 10 ), which has a test switch ( 12 ) over which a test winding ( 52 ) of the zero-phase current transformer ( 5 ) a test current can be supplied, characterized in that the power supply circuit ( 4 ) from a constant current circuit ( 42 ) is constructed, which one from the main circuit ( 2 ) is converted into a direct current to supply the fault current detection circuit ( 6 ) supply a constant direct current and the circuit which supplies the main circuit ( 2 ) with the fault current detection circuit ( 6 ) of the constant current circuit ( 42 ) connects, in series connection, a test resistor element ( 11 ), whose both ends are connected via the test switch ( 12 ) with the test winding ( 52 ) of the zero-phase current transformer ( 5 ) are connected. Residual-current circuit breaker according to claim 1, characterized in that the resistance value of the test resistor element ( 11 ) is less than the internal impedance value of the constant current circuit ( 42 ). Residual-current circuit breaker according to claim 1 or 2, characterized in that the AC input side of the power supply circuit ( 4 ) includes an input resistance element (R ₁ , R ₂ , R ₃ ). Residual-current circuit breaker according to one of claims 1 to 3, characterized in that both ends of the test resistor element ( 11 ) are connected via two constant-voltage diodes (ZD ₃ , ZD ₄ ) connected in series. Residual current circuit breaker, comprising: an opening / closing device ( 8th ) for opening or closing a main circuit ( 2 ); a zero-phase current transformer ( 5 ), through the conductor of all phases of the main circuit ( 2 ) are passed; a fault current detection circuit ( 6 ) based on an output current of a fault current detection winding ( 51 ) of the zero-phase current transformer ( 5 ) the presence of a ground fault is detectable; a sensitivity adjustment circuit ( 61 ) for adjusting the detection sensitivity of the fault current detection circuit ( 6 ); a triggering device ( 7 ) based on one of the fault current detection circuit ( 6 ) output signal representing the presence of a ground fault, the opening / closing means for opening the main circuit is switched off; a power supply circuit ( 4 ), which of the fault current detection circuit ( 6 ) supplies electrical power; and a test circuit ( 10 ), which has a test switch ( 12 ) over which a test winding ( 52 ) of the zero-phase current transformer ( 5 ) a test current is fed, characterized in that a device ( 62 ) is provided, which with the test switch ( 12 ) is coupled to a predetermined sensitivity regardless of the setting of the sensitivity setting circuit (FIG. 61 ). Residual current circuit breaker ( 1 ), which comprises: an opening / closing device ( 8th ) for opening or closing a main circuit ( 2 ); a zero-phase current transformer ( 5 ), through the conductor of all phases of the main circuit ( 2 ) are passed; a fault current detection circuit ( 6 ) based on an output current of a fault current detection winding ( 51 ) of the zero-phase current transformer ( 5 ) the presence of a ground fault is detectable; a response setting circuit ( 63 ) for adjusting the response time of the fault current detection circuit ( 6 ); a triggering device ( 7 ) based on one of the fault current detection circuit ( 6 ) output signal representing the presence of a ground fault, the opening / closing means for opening the main circuit is switched off; a power supply circuit ( 4 ), which of the fault current detection circuit ( 6 ) supplies electrical power; and a test circuit ( 10 ), which has a test switch ( 12 ) over which a test winding ( 52 ) of the zero-phase current transformer ( 5 ) supplies a test current, characterized in that a device ( 64 ) is provided to be connected via a coupling with the test switch ( 12 ) to set a predetermined response time irrespective of the setting of the response setting circuit (FIG. 63 ).