JPS59172920A - Leakage breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in earth leakage breaker.

[Technical background of the invention]

A conventional earth leakage breaker is constructed as shown in FIG. That is, the main circuit conductor 2 provided with the main circuit contact 1 is connected to the power source 3 at one end and to the load 4 at the other end. 5 in the figure is a control circuit for this earth leakage breaker, which has an earth leakage detection circuit 5-1 that performs a tripping operation and a resistor 5-2 that performs a tripping test, and these are made of resin or the like. It is a molded integrated circuit. This control circuit 5 has control power input terminals A, B, detection current input terminals C, D, trip test terminals E, F, and trip command terminals G, H. Inside this control circuit 5, the control power input terminals A and B and the detection current input terminals C and D are connected to an earth leakage detection circuit 5- which performs a tripping operation.
1, and the output end of this earth leakage detection circuit 5-1 is electrically connected to the tripping command terminals G and H described above. On the other hand, trip test terminals E and F
is electrically connected to the resistor 5-2 inside the control circuit 5. As mentioned above, this resistor 5-2 is partially molded with resin or the like together with the earth leakage detection circuit 5-1, and normally, the resistor 5-2 has a built-in power capacity of about 0.3 seconds in terms of the energization time. Control power input terminals A and B, which are external terminals of the control circuit 5, are connected to the main circuit conductor 2 to supply power to the control circuit 5. Further, the secondary side of a zero-phase current transformer 60 whose primary side is passed through as the main circuit conductor 2 is connected to the detection current input terminals C and D. Furthermore, this zero-phase current transformer 6 also has a test circuit conductor 7-1 connected to one side of the main circuit conductor 2 passed therethrough as its primary side. The test circuit conductor 7-1 is connected to the tripping test terminal E via the pushbutton switch 8, and the other tripping test terminal F is connected to the other main circuit conductor 2 via the test circuit conductor 7-2. 8 and a resistor 5-2 pass through the primary side of the zero-phase current transformer 6 and are connected in parallel between the 20 main circuit conductors.

Further, the tripping command terminals G and H are connected to the tripping coil 9. The trip coil 9 is excited by a trip command output from the leakage detection circuit 5-1 of the control circuit 5, and drives a trip mechanism (not shown) to open the main circuit contact 1.

Next, the operation of this earth leakage breaker will be explained. That is, when an earth leakage accident occurs on the load 4 side, a detection current flows through the secondary side of the zero-phase current transformer 60 whose primary side is the main circuit conductor 2, and this is input to the earth leakage detection circuit 5-1 of the control circuit 5. If an electric leakage accident is detected here, a trip command is output, the trip coil 9 is energized, a trip mechanism (not shown) is driven, and the main circuit contact 1 is opened.

Next, a tripping operation test for performing maintenance and inspection of this earth leakage breaker will be explained. That is, the push button switch 8 is closed and a part of the main circuit current flowing through the main circuit conductor 2 is passed through the resistor 5-2 to the primary side of the zero-phase current transformer 6. As a result, a simulated detection current flows through the secondary side of the zero-phase current transformer 60, and as described above, this flows into the earth leakage detection circuit 5- of the control circuit 5.
1, the simulated detection current determines that there is an earth leakage accident, and the tripping coil 9 is energized to drive a tripping mechanism (not shown) to open the main circuit contact 1.

[Problems with background technology]

In the conventional earth leakage breaker as described above, when the operator closes the push button switch 8 and performs a tripping operation test,
If there is a malfunction in the tripping mechanism (not shown), the tripping coil 9, or the control circuit 10, if the main circuit contact 1 does not open with one operation, the pushbutton switch 8 is continuously pressed and held in short periods. This also occurs when the time is closed. However, if the push-button switch 8 is closed for a long time (several seconds), the resistor 5-2, which has a power withstand capacity of about 0.3 seconds based on the energization time, may be burnt out. This also damages the molded control circuit 5 in which the resistor 5-2 is incorporated, making it unusable.

5- [Object of the Invention] The present invention has been made based on the above circumstances, and provides a highly reliable leakage current that does not damage the control circuit even if the push button switch of the tripping operation test circuit is closed for a long time. The purpose is to provide a circuit breaker.

[Summary of the invention]

The earth leakage breaker according to the present invention connects a main circuit by passing a series circuit consisting of a current limiting resistor made of a conductive polymer material having a large positive temperature coefficient of resistance and a push button switch to the primary side of a zero-phase current transformer. The above object is achieved by having a configuration including an earth leakage string removal test circuit connected in parallel to the circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Second
The figure is a circuit configuration diagram showing an embodiment of the earth leakage breaker according to the present invention, and the same parts as in FIG. 1 are denoted by the same symbols.

' In FIG. 2, a main circuit conductor 2 provided with a main circuit contact 1 is connected at one end to a power source 3 and at the other end to a load 4 . 10 in the figure is a control circuit for this earth leakage breaker, which includes an earth leakage detection circuit 10-1 for performing a tripping operation, a resistor 10-2 for performing a tripping test, and a large positive temperature coefficient of resistance. The current limiting resistor 10-3 is made of a conductive polymer material having the following properties, and these are integrated circuits molded with resin or the like. This control circuit 10 has control power input terminals A, B, detection current input terminals C, D, trip test terminals E, F, and trip command terminals G, H. Inside this control circuit 10, the control power input terminals A and B and the detection current input terminals C and D both perform a tripping operation.
-1, and the output terminal of this earth leakage detection circuit 10-1 is the trip command terminal G mentioned above.

It is electrically connected to H. One row removal test terminal E,
F is a resistor 10-2 and a current limiting resistor 10 inside the control circuit 10.
-3 is electrically connected.

The details of the characteristics of this current limiting resistor 10-3 will be described later. On the other hand, control power input terminals A and B, which are external terminals of the control circuit 10, are connected to the main circuit conductor 2 to supply power to the control circuit 10.

Further, a zero-phase current transformer 6 is connected to the detection current input terminals C and D, with the main circuit conductor 2 passing through the main circuit conductor 2 as a primary side. Also, the test circuit conductor 7-1 connected to one side of the main circuit conductor 2
passes through the zero-phase current transformer 6 as the primary side, and the push button switch 8
The other trip test terminal F is connected to the other main circuit conductor 2 by a test circuit conductor 7-2 and passes through the primary side of the zero-phase current transformer 6. A series circuit including a resistor 10-2 and a current-limiting resistor 10-3 is connected in parallel between the lines of the main circuit conductor 2.

Further, the tripping terminals G and H are connected to the tripping coil 9.

The tripping coil 9 is excited by a tripping command output from the earth leakage detection circuit 10-1 in the control circuit 10, and drives a tripping mechanism (not shown) to open the main circuit contact 1.

Next, details such as characteristics of the current limiting resistor 10-3 will be described.

That is, this current limiting resistor 10-3 uses polyethylene containing carbine to provide conductivity, and when this is used as having a current limiting resistor function, for example, as shown in FIG. As shown in the characteristic curve of resistance (Ω) versus temperature (° C.) of a current-limiting resistor, the resistance curve R tends to vary greatly depending on temperature. This shows that when the temperature rises from room temperature to about 130° C., the resistance increases about 106 times. This large increase in resistance occurs because the conductive circuit of the carbon particles is broken due to the volumetric expansion of the carbon particles above a certain temperature. Further, the time it takes for the current to suddenly change due to a sudden increase in resistance, that is, the time it takes for switching to occur, changes depending on the time constant of the temperature rise due to Joule heat generation. In this case, current limiting resistor 10-
It is assumed that the time-integrated value of the current at which resistance 3 suddenly increases is set to a value just before the simulated current continues to flow through the series-connected resistor 10-2 and causes it to burn out.

Next, the operation of the earth leakage breaker configured as described above will be explained. That is, the push button switch 8 is closed, the voltage of the main circuit is applied to the resistor 10-2 and the current limiting resistor 10-3, and a part of the current of the main circuit is applied to the resistor 10-2 and the current limiting resistor 10-3. flows as a simulated leakage current. As a result, a simulated detection current flows through the secondary side of the zero-phase current transformer 6, and as described above, this simulated detection current is input to the earth leakage detection circuit 1θ-1 of the control circuit 10, and an earth leakage accident is detected. Then, the tripping coil 9 is excited and drives a tripping mechanism (not shown) to open the main circuit contact 1.

Next, let us consider the case where a tripping operation test is performed when any of the tripping mechanism (not shown), tripping coil 9, or control circuit 10 of the earth leakage breaker is malfunctioning, that is, when the main circuit contact 1 cannot be opened. state That is, the push button switch 8 is set to 1.
Even if the main circuit contact 1 is closed only once, the main circuit contact 1 will not open, so it will be closed continuously for a long time in short periods. in this case,
A simulated leakage current flows through the series circuit consisting of the resistor 10-2 and the current-limiting resistor 10-3 during the time period when the pushbutton switch 8 is closed, and the current-limiting resistor 10-3 The resistance value increases rapidly just before the time-integrated value of the applied current at which the resistor 1o-2 burns out. As a result, the current limiting resistor 10- has a large resistance value.
Due to the effect of 3, almost no simulated leakage current flows in the series circuit. Therefore, the molded control circuit 10
will not burn out and will not become unusable.

It should be noted that the present invention is not limited to the above embodiments, and can be implemented with various modifications without changing the gist of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, a series circuit consisting of a current limiting resistor made of a conductive polymer material having a large positive temperature coefficient of resistance and a push button switch is connected, one end of which is connected to the primary of a zero-phase current transformer. The configuration includes an earth leakage train disconnection test circuit that is connected in parallel to the main circuit through the side, so even if the push button switch of the tripping operation test circuit is closed for a long time, the control circuit will not be damaged. It is possible to provide an extremely economical and extremely reliable earth leakage breaker.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a conventional earth leakage breaker, Fig. 2 is a circuit diagram showing an embodiment of the earth leakage breaker according to the present invention, and Fig. 3 is a resistance value versus temperature of the current limiting resistor according to the present invention. FIG. 3 is a characteristic curve diagram showing the relationship. 1... Main circuit contact, 2... Main circuit conductor, 3... Power supply 4... Load, 6... Zero-phase current transformer, 7-1.7-2
...Test circuit conductor, 8...Push button switch, 9...
Tripping coil, 10... Control circuit, 10-1... Leakage detection circuit, 10-2... Resistor, 10-3... Current limiting resistor. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] An earth leakage accident occurred in a main circuit consisting of multiple main circuit conductors that have main circuit contacts and connect the power supply and load, a zero-phase current transformer that passes through this main circuit as a primary side, and the main circuit. In the earth leakage breaker which opens the main circuit contact on the condition that the earth leakage detection current flowing to the secondary side of the zero-phase current transformer exceeds the rated value, A current leakage disconnection operation test circuit is provided in which a series circuit consisting of a current limiting resistor made of a molecular material and a push button switch passes through the zero-phase current transformer as the primary side and is connected in parallel to the main circuit. Characteristic earth leakage breaker.