JPH04156221A - Earth leakage breaker - Google Patents

Abstract

PURPOSE:To miniaturize the title circuit breaker and, at the same time, to prevent loaded operation in an undisplayable state due to negligence of resetting operation by providing a reset circuit which outputs a reset signal in accordance with the potential variation caused by the closure of a main contact and resetting a status holding device to the status before a fault occurs by means of the reset signal. CONSTITUTION:In a moment a main contact 5 is manually closed after the cause of a fault is eliminated, the variation of the rise of the output voltage of the second power source circuit 16 is transmitted to the reset coil 26b of a display device 22 through a capacitor 29 as a voltage pulse, namely, reset signal and the reset coil 26b is conducted. Since the coil 26b is conducted in the direction opposite to the conducted direction of a set coil 26a, a core 25 is magnetized to the opposite polarity and a display member 24 is turned by 180 deg.. As a result, the block-colored surface of the member 24 comes out and erases the content displayed on the display device 22.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to an earth leakage breaker that protects the load by disconnecting the load from the power supply line when an earth leakage accident is detected, and particularly relates to an earth leakage breaker that protects the load by disconnecting the load from the power supply line when an earth leakage accident is detected. The present invention relates to an earth leakage breaker that performs the following operations using magnetic state holding means that responds to electrical signals.

(Prior art) In general, an earth leakage breaker has a main contact that is provided in a power supply path to a load such as a motor so as to be able to open and close it, and three-phase conductors that form the power supply path to the load. a zero-phase current transformer which is used as a primary conductor, an earth leakage determination circuit that performs a logical operation to determine the presence or absence of an earth leakage accident based on the detection signal of the zero-sequence current output from the zero-phase current transformer, and a thyristor and this a tripping device that includes an excitation coil that is excited by conduction of the thyristor to open the main contact, and the thyristor is made conductive by a tripping command signal from the earth leakage determination circuit;
It consists of an earth leakage interrupting display device that indicates that the main contact has been opened, that is, that an earth leakage interrupting operation has been performed, and if an earth leakage accident occurs in the load or the load power supply path, this is promptly detected and the main contact is disconnected. It has the function of protecting the load or line by opening it.

(R!S problem to be solved by the invention) In this type of earth leakage circuit breaker, the conventional display device for indicating that the earth leakage interrupting operation has been performed is such that the load power supply path is disconnected from the power supply bus by opening the main contact. Once separated, there would be no way to obtain power for the display, so a mechanical display device was used. This is configured such that the display bar is projected from a hidden position to a visible position in conjunction with the rotational movement of a lever of a release mechanism that constitutes a main contact tripping device. However, with such a configuration, the configuration of the mechanical parts becomes complicated, and the device inevitably becomes larger, especially when trying to meet the demand for incorporating an overcurrent breaker into an earth leakage breaker. This is because it is necessary to move separate indicator bars to distinguish between earth leakage cutoff and overcurrent cutoff, and therefore it becomes necessary to provide separate release mechanisms.

Therefore, an object of the present invention is to configure a display device that displays an earth leakage cutoff with a magnetic state holding means, thereby making it possible to downsize the device, and also to automatically reset the display state so that there is no need to forget the reset operation. An object of the present invention is to provide an earth leakage breaker that can prevent load operation in a state where display is not possible.

[Structure of the invention]

(Means for Solving the Problems) The earth leakage breaker according to the present invention includes a main contact provided to open and close a load power supply path that supplies power to a load, and a zero-phase current transformer provided in the load power supply path. an earth leakage determination circuit that receives the zero-phase detection signal output from the zero-phase current transformer and determines the presence or absence of earth leakage; and receives a tripping command signal from the second earth leakage determination circuit to open the main contact. It consists of a tripping device and a state holding device whose magnetic state is changed in response to an output signal from the earth leakage determination circuit, and which mechanically displaces a display member in response to the change to display an earth leakage accident.

One embodiment of the present invention includes a reset circuit that outputs a reset signal in response to a potential change due to the closing of the main contact, and the reset signal causes the state holding device to be reset to the state before the accident indication.

Another embodiment of the present invention also includes overcurrent detection means that opens the main contact even in the event of an overcurrent such as an overload, and the reset circuit outputs a reset signal even when the overcurrent detection signal exceeds a predetermined value. It has become.

(Function) When an earth leakage accident occurs in a load such as a motor, a zero-sequence current is output from the zero-phase current transformer, and the earth leakage judgment circuit that receives this as a detection signal determines an earth leakage accident and releases a tripping command signal. to the device, thereby opening the main contacts. At the same time, the magnetic state of the state holding device is reversed by the tripping command signal (including signals synchronized therewith), and the display member is moved to the display position to indicate the occurrence of an electric leakage accident. This display is automatically reset by a reset signal generated by the closing of the main contact upon recovery from the accident. If a short-circuit accident or the like occurs and the overcurrent signal increases rapidly, the display member is reset by the reset signal generated based on the overcurrent detection, so it will not malfunction due to the abnormal magnetic field caused by the overcurrent.

(Embodiment) First, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. An overcurrent interrupting function is added to an earth leakage breaker, and a single tripping device is used to interrupt earth leakage and overcurrent. An example of a configuration in which both current interruption and current interruption are performed will be described.

A load power supply path 3 connecting a three-phase power supply bus 1 and a load, for example, an induction motor 2, is opened by energizing an excitation coil 4 that constitutes a tripping device with a release mechanism (not shown). A main contact 5 is interposed in each phase, and a current transformer 6 for detecting overcurrent and a zero-phase current transformer 7 that collectively uses the conductors of each phase as the primary conductor are interposed in each phase, and a zero-phase cutoff function is also provided. In order to test this, a test circuit consisting of a resistor 8 and a test switch 9 is provided on the primary side of the zero-phase current transformer 7 to intentionally form a three-phase non-parallel state.

The output currents of the current transformers 6 of each phase are combined and rectified by the rectifier circuit 10 and then connected to the control power line P1 and the ground 54.
222 to the load circuit 11 and the first power supply circuit 12 for outputting a detection current and securing control power. The overcurrent determination circuit 13 is supplied with power from the first power supply circuit 12 and is constantly supplied with a detection signal S1 corresponding to the passing current value of the load power supply path 3 from the burden circuit 11, and compares this with a reference value for determination. Overcurrent is monitored by constantly performing logical operations, and when overcurrent is determined due to overload or the like, a tripping command signal S2 is output. The thyristor 14 as a switching element has a loop prevention diode 15 between the control power line P1 and the ground 54222.
It is connected in series with the excitation coil 4, and when it receives the tripping command signal S2 at its gate, it turns on, energizes the excitation coil 4, and opens the main circuit contact 5. This is the overcurrent cutoff protection function.

The vA2 power supply circuit 16 for obtaining power for the earth leakage protection function is supplied with power from the two phases of the load power supply path 3, rectifies the power, and controls the DC voltage through the power supply line P3 and the ground 542.
22, and the potential of the control power line P3 is applied to the leakage determination circuit 17 as a non-ground potential, and via the loop prevention diode 19 to the excitation coil 4 as a non-ground potential. Earth leakage determination circuit 1
7 constantly receives the output of the zero-phase current transformer 7, that is, the zero-phase detection signal, and constantly performs a logical operation to compare it with a reference value for judgment, and when the zero-phase detection signal exceeds the reference value, a trip command is issued. It outputs a signal S3. The thyristor 20, which receives this tripping command signal S3 at its gate, has its cathode connected to the ground line P2, and its anode connected to the ground side of the excitation coil 4 via a loop prevention diode 21.
connected via. When this thyristor 20 is turned on by a trip command signal S3 due to an earth leakage accident, the excitation coil 4 is energized and the main contact 5 is opened. This is the earth leakage cutoff function. The display device 22, which is a magnetic state holding device for indicating that this earth leakage interruption has been performed, will be explained with reference to FIGS. 2 to 6. A permanent magnet disk-shaped display member 24 is rotatably supported by the case 23 via shafts 24a provided at two opposing locations. One side of the display member 24 is painted, for example, in yellow, and the other side is painted in a different color, for example, black. In addition, there is a display member 2 inside the case 23.
4, a U-shaped core 25 facing each other across the rotation axes of the two shafts 24a, and a set coil 26 wound around this core.
A magnetic response section 27 consisting of a reset coil 26b and a reset coil 26b is provided. Set, reset coils 26a, 26
b is connected to the terminal t from each end commonly connected to the common terminal tl.
2. The winding direction is opposite to each other end connected to t3.

When either of these set reset coils 26g, 26b is energized, the core 25 is magnetized with a polarity determined by the winding direction of the energized coil, and the display member 24 is rotated 180 degrees in the direction according to the magnetization polarity. Rotated degrees. At this time, excessive rotation is prevented by the stopper 28.

Of the two fills, the set coil 26& has one end connected to the anode of the thyristor 20 and the other end connected to the control power supply R cotton P3 via the diode 19, and the reset coil 26b is connected between the grind line P2 and the control power supply mP3. is connected to via the diode 19 and a capacitor 29 forming a reset signal generating circuit.

Next, the operation of the display function of the earth leakage breaker having the above configuration will be explained. Now, if an earth leakage accident occurs, this is detected by the zero-phase current transformer 7, the earth leakage determination circuit 17 outputs a trip signal S3, and the thyristor 20 is turned on. As a result, the excitation coil 4 is activated by the output voltage of the second power supply circuit 16, that is, the voltage between the control power supply line P3 and the ground line 22.
Since the main contact 5 is opened, the set coil 26g of the display device 22 is also energized via the circuit passing through the diode 19 and the thyristor 20. When the set coil 26a is energized, the core 2
5, the magnetic state is changed to the polarity shown by N and S in FIG. The earth leakage accident status will be displayed in the direction in which it is touched. core 2
The magnetized state of 5 is maintained even if the set coil 26a is cut off by opening the main contact 5. Therefore, no power source is required to maintain the display state. When the cause of the accident is removed and the main contact 5 is manually turned on, at this moment a rising change in the output voltage of the second power supply circuit 16 generates a voltage pulse, that is, a reset signal, to the reset coil 26b of the display unit w22 via the capacitor 29. and reset coil 2
6b is energized. Since the current direction of the reset coil 26b is opposite to that of the set coil 26g,
The core 25 is magnetized with a polarity opposite to that in FIG. 5, as shown by N and S in FIG. 6, so that the display member 24 is
It is rotated 80 degrees to expose its black colored surface and erase the display.

Regarding the above, when the motor 2 falls into an overnegative state, the overcurrent determination circuit 13 outputs the trip signal S2, the thyristor 14 is turned on, and the excitation coil 4 is energized, so the main contact 5 is opened. be done.

However, in this case, the display device 22 is not activated at all, so it can be seen that the leakage is not interrupted. In addition, the tripping signal S2
An overcurrent cutoff display device that responds to the current cutoff is omitted in this example.

By the way, when an abnormal excessive current such as a short circuit current flows into the load power supply path 3, there is a possibility that the magnetic state of the core 25 of the display device 22 may be reversed by the strong magnetic field generated from the excessive current. When such an abnormal overcurrent flows in, a sudden increase in the potential of the control power line P1, which is the output end of the rectifier circuit 10, is transmitted to the capacitor 29 via the diode 15 and the reset coil 26b, and the core 25
Since the display device 22 is magnetized in the reset direction, the display device 22 will not display incorrect information due to the magnetic field generated from the excessive current.

[Effects of the Invention] According to the present invention, the magnetic state of the display means for indicating when the earth leakage interrupting operation is performed is changed in response to an electric signal, and the display member is mechanically displaced by the change. Since the configuration is such that the display state is formed using the display function, there are no complicated mechanical parts and the device becomes compact.For example, when adding an overcurrent cutoff function, the release mechanism can be shared without being restricted by the display function This makes it possible to unify the device, which greatly contributes to downsizing the device.Also, since the display status is automatically reset by turning on the power to the load power supply line again, it is possible to avoid load operation in a state where the display is not possible due to forgetting the reset operation. It can be prevented.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a first embodiment of the present invention, Fig. 2 is a plan view of the display device, Fig. 3 is a side view thereof, Fig. 4 is a bottom view thereof, and Figs. 5 and 6 are FIG. 3 is a diagram for explaining the operation of the display device. In the figure, 2 is a motor, 3 is a load power supply path, 4 is an exciting coil,
5 is a main contact, 6 is a current transformer, 7 is a zero-phase current transformer, 13 is an overcurrent determination circuit (overcurrent detection means), 17 is an earth leakage determination circuit,
22 is a display device (state maintaining device, 24 is a display member, 2
5 is a core, 26a is a set coil, 26b is a reset coil, and 29 is a capacitor (reset signal generation circuit). Agent Patent Attorney Tsuyoshi Sato Figure 1 Figure 4

Claims (1)

[Claims] 1. A main contact provided to open and close a load power supply path that supplies power to a load, a zero-phase current transformer provided in the load power supply path, and this zero-phase current transformer. an earth leakage determination circuit that receives a zero-phase detection signal output from the earth leakage determination circuit to determine the presence or absence of earth leakage; a tripping device that receives a tripping command signal from the earth leakage determination circuit and opens the main contact; An earth leakage breaker comprising a magnetic response section whose magnetic state is changed in response to an output signal of the magnetic response section, and a state holding device having a display member that is mechanically displaced by the magnetic change of the magnetic response section. 2. A reset signal generation circuit is provided that outputs a reset signal in response to a potential change caused by the closing of the main contact, and the state holding device uses the reset signal to reset the magnetic state of the magnetic response section to the state before the response. The earth leakage breaker according to claim 1, characterized in that: 3. Overcurrent detection means is provided to detect overcurrent in the load power supply path and operate the tripping device, and the reset signal generation circuit detects overcurrent when the detection signal from the overcurrent detection means exceeds a predetermined value. 3. The earth leakage breaker according to claim 2, wherein the earth leakage breaker also outputs a reset signal.