JPS6110826A - 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] [Field of Application of the Invention] The present invention provides overcurrent, current and leakage protection using a static trip circuit, and an earth leakage interrupter equipped with an earth leakage display device for determining the cause of operation. Concerning vessels.

[Background of the invention]

In recent years, in response to customer demands for protection of not only wiring but also loads with molded circuit breakers, so-called electronic overcurrent relays have been developed that have made the overcurrent protection element stationary and can provide arbitrary protective operating characteristics. is being developed. In this case, an arsenic trip device that operates with a small amount of electrical energy is generally used as an electro-mechanical converter that opens a contact in response to an operating signal from a trip circuit. The overcurrent detection current transformer, which is both a power source and a power source, has been made smaller.

A conventional example of an earth leakage breaker using such an electronic overcurrent relay as an overcurrent protection element is shown in Fig. 1. In the figure, reference numeral 1 indicates an overcurrent detection current transformer provided in each phase of the protected circuit, and the output of the current transformer is subjected to three-phase full-wave rectification by a rectifier circuit 2. 37 converts it into a voltage, and applies it as a signal and power source to the overcurrent trip circuit 3 consisting of an electronic circuit. The overcurrent trip circuit 3 includes a resistor 36.
When the signal voltage divided by 37 exceeds a certain set value, an operating signal is generated after a delay time corresponding to the magnitude of the signal voltage. This operation signal causes the thyristor 4, which is the first switching element, to conduct, applying the output voltage of the rectifier circuit 2 to the tripping coil 5 of the magnetic tripping device, and causing the magnetic tripping device to open the contact 6. In the event of an earth leakage accident, the output generated by the zero-phase current transformer 7 is converted into a voltage signal by the resistor 38 and applied to the IT trip circuit 8 consisting of an electronic circuit. When the input signal voltage exceeds a set value, the earth leakage side removal circuit 8 generates an operating signal after a certain delay time. This operation signal causes the thyristor 9, which is the second switching element, to conduct, energizing the leakage side disconnection coil 10, which causes the contactor 6 to open, thereby interrupting the protected circuit. The earth leakage display button 11 is mechanically disengaged and protrudes from the case of the circuit breaker, so that the cause of the operation (overcurrent or leakage) can be determined after the circuit breaker is disconnected.In the event of an earth leakage accident, Since the detected leakage current itself is as small as several tens of ma, the output necessary for the power supply cannot be obtained from the zero-phase current transformer 7, so the voltage of the protected circuit is rectified by the rectifier circuit 12 and the leakage side disconnection circuit 8 is used. It is used as a power source for the leakage side removal coil 10. 39, 40, and 41 are current limiting resistors.

However, the conventional earth leakage circuit breaker described above has the following problems.

(1) Figure 2 shows both the earth leakage side disconnection characteristics and the overcurrent tripping characteristics. Generally speaking, there is a limit to the balance of the zero-phase current transformer 7 used for earth leakage detection, and the zero-phase current Even if no current flows, there is a region (region to the right of the broken line in FIG. 2) in which the leakage side disconnection circuit 8 operates due to residual current generated on the secondary side of the zero-sum current transformer due to overcurrent. Normally, the limit of this equilibrium characteristic is raised by applying a magnetic shield to the zero-phase current transformer or by making the windings and core magnetic permeability uniform so as not to impair the overcurrent trip characteristic.

However, in the circuit configuration shown in FIG. 1, when an overcurrent exceeding the equilibrium characteristic limit flows, the earth leakage side disconnection coil 10 is also activated by the operation signal generated by the earth leakage side disconnection circuit 80, so that the earth leakage side disconnection coil 10 is activated. protrudes outside the case, erroneously indicating the cause of the operation to the user.

(2) Overcurrent tripping coil 5 and earth leakage side disconnecting coil 1
In order to commonly transmit the mechanical output of 0 to the opening/closing mechanism of the contactor 6, an intervening member such as a common release shaft or interlocking plate is required.
An increase in the inertial mass of the motion transmission system due to these inclusions prolongs the operation time in the event of a short circuit accident, resulting in a decrease in return cutoff performance.

(5) Since two tripping coils are required, the price is also high.

[Purpose of the invention]

An object of the present invention is to use a common tripping coil for overcurrent protection and earth leakage protection, and to provide a configuration in which an earth leakage display device does not malfunction due to an overcurrent that exceeds the balance limit of a zero-phase current transformer for earth leakage detection. Therefore, it is an object of the present invention to provide an earth leakage breaker that does not cause false indications and has better short-circuit breaking performance.

[Summary of the invention]

The present invention relates to a current transformer for overcurrent detection, a zero-phase current transformer for earth leakage detection, an overcurrent trip circuit that generates an operation signal after a time corresponding to each fault by the output of these current transformers, and an overcurrent trip circuit on the earth leakage side. A first switching element that is made conductive by the operation signal of the overcurrent tripping circuit; a second switching element that is made conductive by the operation signal of the leakage side tripping circuit; a tripping coil that operates as a contactor; and an earth leakage display. the side-removal coil is commonly connected to the first switching element and the second switching element, and is configured to provide a voltage obtained by rectifying the output of the overcurrent detection current transformer and a voltage obtained by rectifying the protected circuit voltage. The earth leakage display device has a display coil connected in series with the second switching element and in parallel with the first switching element, and is energized by the logical sum of the zero-phase current transformer for earth leakage detection. The first switching element is configured to become conductive earlier than the second switching element in response to an overcurrent that exceeds the equilibrium characteristic limit. It is a circuit breaker.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 3 to 6. FIG. 6 is a circuit diagram of an embodiment of the present invention, and parts having the same functions as those in FIG. 1 are designated by the same reference numerals.

In FIG. 3, the output of the overcurrent detection current transformer 1 is subjected to three-phase full-wave rectification by a rectifier circuit 2, and converted to voltage by a resistor 3 (S, 37).The overcurrent trip circuit 3 is connected to a resistor 36. When the signal voltage divided by 37 exceeds a certain set value, an operation signal is generated after a delay time corresponding to the magnitude of the signal voltage, and the first
This is an electronic circuit that conducts the thyristor 4, which is a switching element, and is a well-known circuit that performs inverse time-limiting operation and instantaneous operation similarly to the overcurrent tripping circuit 3 of FIG.

On the other hand, the output of the zero-phase current transformer 7 for earth leakage detection is converted into a voltage signal by a resistor 38 and applied to the earth leakage side disconnection circuit 8. The earth leakage side removal circuit 8 is an electronic circuit that generates an operating signal after a predetermined delay time when the input signal voltage exceeds a certain set value and makes the thyristor 9, which is the second switching element, conductive. This is a known circuit similar to No. 8.

Reference numeral 5 denotes a tripping coil of a magnetic side disconnection device that also serves as overcurrent and earth leakage protection.This tripping coil 5 is commonly connected to the first switching element 4 and the second switching element 9, and is P is energized by the logical sum of the voltage obtained by rectifying the output of the detection current transformer 1 by the rectifier circuit 2 and the voltage obtained by rectifying the protected circuit voltage by the rectifier circuit 12. In a region where the accident current is relatively small, such as an overload accident, the trip coil 5 is energized by the output voltage of the rectifier circuit 12 applied via the second switching element 9, the diode 43, and the first switching element 4. In a region where fault current such as a short circuit is high and the voltage of the protected circuit is reduced, the contactor 6 is opened, and the rectifier circuit 2 is applied via the first switching element 4 and the diode 42. The trip coil 5 is energized by the output voltage, and the contact 6 is opened. In addition, power is supplied to the overcurrent trip circuit 5 from the rectifier circuit 2, power is supplied to the earth leakage side disconnection circuit 8 from the rectifier circuit 12, and the diode 4 is supplied with power from the rectifier circuit 2.
2 prevents the output voltage of the rectifier circuit 12 from interfering with the overcurrent tripping circuit 3. With this configuration, overcurrent protection and earth leakage protection are ensured using the common tripping coil 5. In the conventional example shown in FIG. 1, the common side tripping shaft and interlocking that were necessary to commonly transmit the mechanical output of the overcurrent tripping coil 5 and the leakage side tripping coil 10 to the opening/closing mechanism can be Since there is no need for inclusions such as wire, the inertial mass of the motion transmission system is reduced, the operating time in the event of a short circuit accident can be shortened, and the interrupting performance can be improved. It's the first one.
In the conventional example shown in the figure, the trip coil 5 had to be operated by the output of the current transformer 2 even in the event of an overload with a relatively small fault current, but with the above configuration, such a fault current can be In a small area, the trip coil 5 can be operated with a voltage obtained by rectifying the protected circuit voltage, so the load on the current transformer 2 is reduced accordingly, and the current transformer 2 can be made smaller.

Next, the leakage a display will be described. In FIG. 3, the earth leakage display device 21 has an independent display coil 13, and this display coil 16 is connected in series with the second switching element 9 and the diode 43, and in parallel with the first switching element 4. There is. When the overcurrent exceeds the equilibrium characteristic limit of the zero-phase current transformer 7 for earth leakage detection, the first switching element 4 becomes conductive earlier than the second switching element 9 due to the instantaneous operation of the overcurrent tripping circuit B. The operating times of the overcurrent trip circuit 5 and the earth leakage side disconnect circuit 8 are coordinated. By doing this, there will be a second protection against electrical leakage accidents.
Since the output voltage of the rectifier circuit 12 is applied to the tripping coil 5 and the display coil 13 due to the conduction of the switching element 9, the display coil 16 is activated at the same time as the -1 disconnection coil 5 opens the contactor 6. However, when the first switching element 4 becomes conductive in response to an overcurrent, almost the entire voltage is applied to the tripping coil 5, and the indicating coil 13 is almost short-circuited, so even if there is a leakage, Even if an overcurrent exceeding the equilibrium characteristic limit of the detection zero-phase current transformer 7 flows and the second switching element 9 is made conductive due to a malfunction of the leakage side disconnection circuit 8 before the contact 6 completes opening, the display coil No voltage is applied to 13, so that the earth leakage display device 21 will not erroneously display an earth leakage indication.

The earth leakage display device 21 can display an earth leakage accident in any format, such as a falling target or a protruding button, and can maintain the display state even after the protected circuit is cut off.
The figure shows an example in which the electric leakage is displayed by protruding the display button 11.

FIG. 4 is a diagram showing an example of the configuration of the earth leakage display device 21, in which the display button 11 is attached to the movable iron core 14, and the cylindrical guide 20
can move in the axial direction together with the movable iron core 14 while being guided by the movable iron core 14. Normally, the magnetic flux generated by the permanent magnet 15 passes through the armature surfaces of the movable core 14 and the fixed core 17 via the yoke 16 and the auxiliary yaw 18, and the attractive force of this magnetic flux overcomes the driving force of the spring 19, as shown in the figure. Movable iron core 1 as in
4 is attracted to the fixed iron core 17, but when the leakage side is removed, the display coil 13 is energized.
This generates a magnetic flux in the opposite direction to the magnetic flux caused by the magnetization, and the magnetic flux on the armature surface is canceled out.
moves upward in the figure to project the display button 11 to the display position. After the operation, when the display button 11 is pressed by hand, the state returns to the state shown in the figure.

FIG. 5.6 is a partial sectional view of an earth leakage interrupter incorporating this earth leakage display device 21, and the same reference numerals as in other figures indicate the same parts. As shown in Fig. 5.6, the earth leakage display device 21 is installed together with the magnetic side disconnection device 22 at one pole other than the central pole where the opening/closing mechanism of the circuit breaker is installed.

FIG. 5 is a diagram showing the closed circuit state of the circuit breaker. In this state, the display button 11 does not protrude from the main body case 23, but
When disconnecting the leakage side, press the display button 11 as shown in Figure 6.
protrudes from the main body case 23 to notify the user that the trip is due to an electrical leakage.

At the time of overcurrent disconnection, only the operating handle 24 of the opening/closing mechanism is in the trip position, and the display button 11 does not protrude, so it can be seen that the trip is due to overcurrent.

The magnetic side removal device 22 operates as follows.

Normally, the movable iron core 26 is moved by the magnetic flux generated by the permanent magnet 25.
The attractive force acting on the armature surface of the fixed core 27 overcomes the driving force of the spring 28, and the movable core 26 is moved as shown by the solid line in FIG.
is attracted to the fixed iron core 27, and the other end of the movable iron core 26 is separated from the trip shaft 29. During overcurrent disconnection and leakage side disconnection, the tripping coil 5 is energized to generate a magnetic flux in the opposite direction to the magnetic flux produced by the permanent magnet 25, and this magnetic flux cancels the magnetic flux on the armature surface, so that the movable iron core 2
6 is rotated by the driving force of the spring 2B to the position shown by the two-point chain in FIG. 5, and the other end pushes the trip shaft 29 to move it to the left in the figure. As a result, the latch at the central pole (not shown) is released, and the opening/closing mechanism is operated to open the movable frame 31, which is attached to the insulating shaft 60 common to each pole, in a clockwise direction. The movable contact 6 is separated from the fixed contact 32.

FIG. 6 shows a state in which contact opening has been completed. At this time, the movable iron core 26 is pushed back to its original position by the tip of the torsion spring 64, which is attached to the movable contactor 60 rotation point shaft 35 and applies contact pressure. do. In FIG. 5.6, 35 is a through conductor of the current transformer 10 for overcurrent detection, which is connected to the movable contactor 6 and the load side terminal (not shown).

〔Effect of the invention〕

According to the present invention, when an overcurrent exceeding the equilibrium characteristic limit of a zero-phase current transformer for earth leakage detection flows into the protected circuit and the leakage side disconnection circuit malfunctions due to the residual current generated on the secondary side of the zero-phase current transformer. However, since the display coil of the earth leakage display device is not energized, it is possible to prevent the earth leakage display device from erroneously displaying information, similar to earth leakage circuit breakers using conventional electronic overcurrent relays. Since the disconnection coil is common to overcurrent protection and earth leakage protection, the common trip shaft and interlocking that were necessary in the conventional example to transmit the mechanical output of the overcurrent tripping coil and the earth leakage tripping coil to the opening/closing mechanism in common have been eliminated. This eliminates the need for inclusions such as plates, reduces the inertial mass of the motion transmission system, shortens the operating time against short-circuit accidents, improves interrupting performance, and provides an inexpensive structure.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional earth leakage breaker using an electronic overcurrent relay, Fig. 2 is its operating characteristic diagram, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 is a partially cutaway side view showing an example of the configuration of the earth leakage display device in FIG. 6, and FIGS. 5 and 6 are partial sectional views of an earth leakage breaker incorporating this earth leakage display device. 1: Overcurrent Detection current transformer, 2: Rectifier circuit that rectifies the output of current transformer 1, 3: Overcurrent trip circuit, 4
: first switching element, 5: tripping coil, 6: contactor, 7: zero-phase current transformer for earth leakage detection, 8: earth leakage tripping circuit, 9: second switching element, 12: captured circuit voltage Rectifier circuit for rectification, 13: Display coil, 21...
Electric leakage display device $ 2 Figure atmosphere barley
Foothole Nananagiryu 1: Ri 1 Moran 2) A - 4th Fig. 6121 Power 3/30

Claims (1)

[Claims] A current transformer for overcurrent detection, a zero-phase current transformer for earth leakage detection, and an overcurrent trip circuit and earth leakage trip circuit that generate operating signals after a time corresponding to each fault by the output of these current transformers. , a first switching element that becomes conductive in response to an operating signal of an overcurrent tripping circuit, a second switching element that becomes electrically conductive in response to an operating signal of an earth leakage tripping circuit, a tripping coil that operates to open a contact, and an earth leakage display device. The tripping coil is commonly connected to the first switching element and the second switching element, and has a logic between a voltage obtained by rectifying the output of the overcurrent detection current transformer and a voltage obtained by rectifying the protected circuit voltage. The earth leakage display device has an indicating coil connected in series with the second switching element and in parallel with the first switching element, and the balance characteristic limit of the zero-phase current transformer for earth leakage detection. An earth leakage circuit breaker configured such that the first switching element becomes conductive earlier than the second switching element in response to an overcurrent exceeding .