JPH0993785A - Earth leakage breaker and breaker for wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a load by detecting an abnormal voltage generated owing to missing of phase of the neutral line to isolate the contacts of main circuit if a detected voltage exceeds the reference voltage. SOLUTION: When the phase A is positive, and the phase B is zero potential, a current flows to the phase B from the phase A via the loads 41a and 41b. A detected current Id flows to an abnormal voltage detecting circuit 13 from the load 41a via the neutral line Nz, diode 38z and a voltage detection lead 15 and moreover flows to the phase B via the diode 14b. Since the detected current Id is impeded by the diodes 38x and 38y at the common connecting point Pk of the cathodes of diodes 38x to 38z, it flows into the abnormal voltage detecting circuit 13 without creeping to the neutral line Nx or Ny of the other normal distribution board 21X or 21Y. Abnormal voltage Vzb applied to the load 41b is detected by the abnormal voltage detecting circuit 13 and the main circuit contacts are isolated by the protection circuit to protect the load 41b from abnormal voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage circuit breaker for detecting an abnormal voltage generated when a neutral phase of a neutral line of a single-phase three-wire type distribution line is open and performing an open-phase protection operation to open a main circuit contact. And a circuit breaker for wiring.

[0002]

2. Description of the Related Art An example of such a conventional earth leakage breaker is shown in FIG.
Shown in 6, which shows the electrical configuration of the earth leakage breaker 19, the main circuit 1 includes two power supply lines A and B (A and B phases).
And a neutral line N (N phase), which is a single-phase three-wire type distribution line, and has power source side terminals 2a, 2b and 2n on the input side.
Load side terminals 3a, 3b and 3n are provided on the output side. The main circuit 1 is provided with a main circuit contact 5 which can be opened and closed by a trip coil 4. Thermal relays 6a and 6b are inserted in the power supply lines A and B on the load side of the main circuit contact 5, and a diode 7 is provided.
The anodes a and 7b are connected to each other.

The cathodes of the diodes 7a and 7b are connected in common, and the common connection point is the trip coil 4
Also, it is grounded through the series circuit of the thyristor 8 and is connected to the input terminal of the DC power supply circuit 9. The DC power supply circuit 9 creates a stabilized DC power supply from the diodes 7a and 7b that have undergone full-wave rectification of the AC voltage, and supplies the operating power supply to each internal circuit of the earth leakage breaker 19.

Further, the main circuit 1 is provided with a zero-phase current transformer 10, and the output terminal of the zero-phase current transformer 10 is connected to the input terminal of the leakage detection circuit 11. The leakage detection circuit 11 detects the A, B and N-phase currents flowing in the main circuit 1 by the zero-phase current transformer 10 in a lump,
The ground fault current (leakage current) flowing in the ground is detected. The output terminal of the leakage detection circuit 11 is connected to the input terminal of the protection circuit 12.

The input terminals of the abnormal voltage detection circuit 13 are respectively connected to the power lines A and B on the load side through the diodes 14a and 14b whose anodes are commonly connected.
Further, the abnormal voltage detection lead wire 1 of the abnormal voltage detection circuit 13
Reference numeral 5 is drawn out from the main body of the earth leakage breaker 19 and connected to a load-side neutral wire (not shown).
An abnormal voltage generated between N phases or between B and N phases is detected. The output terminal of the abnormal voltage detection circuit 13 is connected to the input terminal of the protection circuit 12.

The series circuit of the test circuit resistor 16 and the test switch 17, which is a push switch, is connected between the power supply lines A and B so that one of the electric circuits runs through the zero-phase current transformer 10. The operation of the leakage detection circuit 11 is tested by turning on the test switch 17.

The output terminal of the protection circuit 12 is the thyristor 8
Connected to the gate. Then, the protection circuit 12
When the abnormal voltage detection circuit 13 detects an abnormal voltage due to the open phase of the neutral wire N or the leakage detection circuit 11 detects a leakage current, a control signal is applied to the gate of the thyristor 8 to energize the trip coil 4, The main circuit contact 5 is opened. Also, this trip coil 4
When the opening / closing operation is performed by, the operation display device 18 including, for example, an LED is turned on to perform display. The above constitutes the earth leakage breaker 19.

Now, the operation of the abnormal voltage detection circuit 13 will be described with reference to FIG. FIG. 7 shows different impedances Za and Zb (Z-Z between the A-N phase and the B-N phase).
b> Za), the loads 20a and 20b are connected to each other, and the current flows when the neutral wire N is out of phase (A phase is positive,
The B phase shows zero potential. At this time, the current I is A
Flowing from the phase to the B phase via the loads 20a and 20b, and the detection current Id from the load 20a via the abnormal voltage detection lead wire 15 to the voltage dividing resistor 13a of the abnormal voltage detection circuit 13.
And 13b, and to the B phase through the diode 14b.

A load 20a is provided between the A-N phase and the B-N phase.
The voltages Va and Vb are generated according to the impedance ratios of 20 and 20b, and the voltage Vb becomes an abnormal voltage. The abnormal voltage Vb is also applied to the series circuit of the voltage dividing resistors 13a and 13b of the abnormal voltage detecting circuit 13, and the divided abnormal voltage Vb 'is detected between the terminals of the voltage dividing resistor 13b. Then, the protection circuit 12 compares the detected voltage Vb ′ with the reference voltage and opens the main circuit contact 5 when the detected voltage Vb ′ is equal to or higher than the reference voltage.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As shown in FIG.
Now, consider a case where power is supplied to a plurality of, for example, three distribution boards 21X, 21Y, and 21Z via the earth leakage breaker 19. That is, the load side terminals 3a, 3b of the earth leakage breaker 19
And 3c are connected to the power supply lines Ax and Bx of the distribution board 21X and the neutral line Nx, and the power supply lines Ay and Ay of the distribution board 21Y,
By and the neutral line Ny, and the feeder lines Az and B of the distribution board 21Z
z and the neutral line Nz are also connected. Then, from these distribution boards 21X, 21Y and 21Z, power is supplied to various loads via a plurality of breakers Px, Py and Pz.

The abnormal voltage detection lead wire 15 of the earth leakage breaker 19 is connected to one end on the load side of the neutral line Nz of the distribution board 21Z, for example. In this case, the abnormal voltage due to the open phase generated at the point R of the neutral line Nz is detected by the abnormal voltage detection circuit 13. However, the distribution board 21X
When the open phase occurs at the point P of the neutral line Nx or the point Q of the neutral line Ny of the distribution board 21Z, the detection current Id does not flow in the abnormal voltage detection circuit 13, and the abnormal voltage is not detected.

Therefore, in order to detect the open phase at the point P or Q and protect the load, the distribution board 21X,
It is necessary to separately install each of the earth leakage breakers 19 with respect to 21Y, which causes a problem that an installation space and a cost are increased and a wiring work is complicated.

The present invention is intended to solve the above problems, and an object thereof is to detect a missing phase of a neutral line generated in each distribution board even when a single unit is connected to a plurality of distribution boards to supply power. Another object of the present invention is to provide an earth leakage breaker and a wiring breaker capable of protecting a load.

[0014]

In order to achieve the above object, the earth leakage circuit breaker according to claim 1 has a main circuit contact provided in a single-phase three-wire distribution line for supplying power to a load, and a single-phase contact. A terminal having a leakage detection circuit for detecting a ground fault current flowing in a three-wire type distribution line and a plurality of terminal plates to which neutral wires of a plurality of distribution boards connected to the load side of the main circuit contacts are respectively connected The base and the anode are connected to each terminal board of the terminal block,
Also, a plurality of rectifying elements whose cathodes are commonly connected,
When the cathodes of the plurality of rectifying elements are connected, an abnormal voltage detection circuit for detecting an abnormal voltage generated due to a neutral phase open phase, and when the detection voltage of the abnormal voltage detection circuit becomes equal to or higher than a reference voltage, or And a protection circuit that opens the main circuit contact when the earth leakage detection circuit detects a ground fault current.

In this case, a plurality of rectifying elements may be housed inside the terminal block (claim 2). A circuit breaker for wiring according to a third aspect has a protection function for the earth leakage circuit breaker according to the first or the second aspect.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an earth leakage circuit breaker will be described below with reference to FIGS. 1 to 5. The same portions as those in FIGS. 6 to 8 are designated by the same reference numerals. Show. In FIG. 2 showing the upper surface of the earth leakage breaker 30, the earth leakage breaker 30 is configured by adding a terminal block 31 to the left side surface portion of the conventional earth leakage breaker 19. Earth leakage breaker 3
The power supply side terminals 2a, 2b and 2n are arranged in the upper part of 0, and the load side terminals 3a, 3b and 3n are arranged in the lower part. In addition, at the center of the earth leakage breaker 30, the operation lever 32 is provided from the inside of the earth leakage breaker 30 to the main body case 30a.
Through the opening 30b. The test switch 17 described above is provided on the right side of the operation lever 32, and the operation display device 18 is provided on the left side.

As shown in FIG. 3, the terminal block 31 is provided with a stepped lead wire terminal portion 33 inside the upper cover 31a removed therefrom. A plurality of terminal fittings 34, which are terminal plates, are attached to the lead wire terminal portion 33. Each of the inner lead wire terminals 35 of these terminal fittings 34 extends downward from the outer lead wire terminal 36 so as to face the inner insulating barrier 31b, and the tip end thereof is retracted from the inner insulating barrier rear 31b to the outside. Is provided with an inclination, and the tip end thereof is burred to form a screw hole (not shown).

Then, crimp terminals 37Xa, 37Ya and 37Za connected to one ends of the lead wires 37X, 37Y and 37Z are respectively connected to the three external lead wire terminals 36 by screwing, and the lead wires 37X, 37Y and 37Z are connected. Three
The other end of 7Z is connected to the load-side ends of the neutral lines Nx, Ny, and Nz of the distribution boards 21X, 21Y, and 21Z, respectively (see FIG. 4).

Inside the terminal block 31, diodes 38x, 38y and 38z which are rectifying elements are arranged. The crimp terminals 39a of the three lead wires 39 connected to the anodes of the diodes 38x, 38y, and 38z are connected to the three internal lead wire terminals 35 by screwing. Diodes 38x, 38y and 38
The cathode of z is commonly connected to the closed terminal 40,
The closed terminal 40 is provided from the inside of the main body of the circuit breaker 30 to the window portion 3 provided in the inner insulating barrier 31b of the terminal block 31.
Abnormal voltage detection lead wire 15 pulled out through 1c
It is connected to the.

The terminal block 31 constructed as described above is provided with locking claws 31d, 31 protruding from the inner insulating barrier 31b.
By fitting and locking d into an engagement notch (not shown) provided on the side of the body case 30a, it is attached to the left side surface of the earth leakage breaker 30 in a retaining state.

FIG. 1 shows the electrical connection of the earth leakage breaker 30. That is, the diodes 38x, 38y and 3 are connected to the abnormal voltage detection lead wire 15 of the circuit shown in FIG.
In this configuration, the commonly connected cathodes of 8z are additionally connected.

Next, the operation of this embodiment will be described with reference to FIGS. 4 and 5. 4 and 5 show a state in which the earth leakage breaker 30 is connected to the distribution boards 21X, 21Y and 21Z. For example, as shown in FIG. 5, loads 41a and 41b having impedances Zza and Zzb are connected between the A-N phase and the B-N phase of the distribution board 21Z (Zza <Zzb), and the distribution board 21Z. Neutral line N
It is assumed that a phase loss (disconnection) occurs at a point R of z.

Then, as in the case shown in FIG. 7, when the A phase is positive and the B phase is zero potential, the current flows from the A phase to the load 41a.
And 41b to the phase B, and the detection current Id
Is connected to the abnormal voltage detection circuit 13 from the load 41a via the neutral wire Nz, the diode 38z and the abnormal voltage detection lead wire 15.
To the B phase via the diode 14b.

In this case, the detection current Id is the diode 3
At the common connection point Pk of the 8x to 38z cathodes,
Blocked by diodes 38x and 38y,
An abnormal voltage applied to the load 41b because the abnormal voltage detection circuit 13 flows to the neutral line Nx or Ny of another sound distribution board 21X or 21Y without causing a sneak as shown by a dotted line in the figure. The voltage Vzb is detected by the abnormal voltage detection circuit 13. Thus, the protection circuit 12 can open the main circuit contact 5 to protect the load 41b from abnormal voltage.

Further, even when the neutral line Nx or Ny of the distribution board 21X or 21Y has a missing phase (for example, the point P or the point Q in FIG. 4), the detected current Id passes through the diode 38x or 38y. Abnormal voltage detection circuit 1
Since the current flows in the same manner, the load connected between the phases can be protected in the same manner.

As described above, according to this embodiment, the earth leakage breaker 30 is connected to the neutral lines N of the distribution boards 21X, 21Y and 21Z.
x, Ny, and Nz are connected to the anodes of the diodes 38x, 38y, and 38z through the lead wire terminal portion 33, respectively, and the cathodes of these diodes 38x, 38y, and 38z are connected to the abnormal voltage detection circuit 13, and the abnormal voltage is detected. When the detection circuit 13 detects an abnormal voltage due to the open phase of any of the neutral wires Nx to Nz, the protection circuit 12 opens the main circuit contact 5.

Therefore, by installing one earth leakage breaker 30 for each of the three distribution boards 21X to 21Z, it is possible to detect a phase loss occurring in any of the neutral wires Nx to Nz. And the wiring work can be facilitated.

Further, according to the present embodiment, the diode 38
Since x, 38y, and 38z are housed inside the terminal block 31, the earth leakage breaker 30 can be made compact and the installation space can be further reduced.

The present invention is not limited to the embodiments described above and shown in the drawings, but the following modifications and expansions are possible. The earth leakage breaker 30 is provided with an overcurrent detection circuit for detecting an overload and a short-circuit state of the main circuit 1, and the protection circuit 12 is mainly used even when the overcurrent detection circuit detects an overcurrent flowing in the main circuit 1. The circuit contact 5 may be configured to be opened to have a function as a circuit breaker for wiring.
In this case, the load can be protected from the overcurrent flowing in the main circuit 1.

The number of terminals and diodes provided in the lead wire terminal portion 33 of the terminal block 31 is not limited to three and may be changed as appropriate. The number of distribution boards to be connected may be changed accordingly. Further, the terminal block 31 may be provided on the right side portion or both side portions of the earth leakage breaker 30. The rectifying element is not limited to a diode, and any element having a rectifying function may be used.
The diodes 38x, 38y, and 38z may be provided inside the main body of the earth leakage breaker 30 instead of being provided inside the terminal block 31.

[0031]

Since the present invention is as described above,
The following effects are obtained. According to the earth leakage circuit breaker of claim 1, when any of the neutral wires of the plurality of distribution boards is out of phase, current flows to the abnormal voltage detection circuit through any of the plurality of terminal boards and the rectifying element. , The abnormal voltage detection circuit detects the abnormal voltage generated due to the open phase of the neutral line, and the protection circuit detects the ground fault current when the detected voltage exceeds the reference voltage or the earth leakage detection circuit. Since the main circuit contacts are sometimes separated, the load can be protected by detecting a phase loss that has occurred in any of the neutral wires of multiple distribution boards with one unit, reducing the installation space and cost. As a result, the wiring work can be simplified.

According to the earth leakage circuit breaker of the second aspect, since the rectifying element is housed inside the terminal block, it can be made smaller and the installation space can be further reduced. According to the wiring circuit breaker of claim 3, in addition to the protection function of the earth leakage circuit breaker of claim 1 or 2, it is possible to perform overload and short circuit protection of the main circuit.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram of an earth leakage breaker showing an embodiment of the present invention.

FIG. 2 is a plan view of an earth leakage breaker.

FIG. 3 is a side view showing the structure of the terminal block with a part thereof broken away.

FIG. 4 is a configuration diagram showing a connection between an earth leakage breaker and a plurality of distribution boards.

FIG. 5 is a circuit diagram showing a connection between an earth leakage breaker and a plurality of distribution boards.

FIG. 6 is a diagram corresponding to FIG.

FIG. 7 is a diagram showing a current flowing through a load and an abnormal voltage detection circuit when a phase of a neutral line is lost.

FIG. 8 is a view corresponding to FIG.

[Explanation of reference numerals] 5 is a main circuit contact, 11 is a leakage detection circuit, 12 is a protection circuit, 13 is an abnormal voltage detection circuit, 30 is an earth leakage breaker, 31
Is a terminal block, 34 is a terminal fitting (terminal plate), 38x, 38y
And 38z are diodes (rectifying elements), 41a and 41
b shows a load.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H02H 3/34 H02H 3/347 A 3/347 H02B 9/00 E

Claims (3)

[Claims] 1. A main circuit contact provided on a single-phase three-wire type power distribution line for supplying power to a load, an earth leakage detection circuit for detecting a ground fault current flowing in the single-phase three-wire type power distribution line, and the main circuit. A terminal block having a plurality of terminal plates to which neutral wires of a plurality of distribution boards connected to the load side of the circuit contacts are respectively connected, and an anode connected to each terminal plate of the terminal block,
In addition, a plurality of rectifier elements whose cathodes are commonly connected, an abnormal voltage detection circuit which is connected to the cathodes of the plurality of rectifier elements, and which detects an abnormal voltage generated due to the neutral phase open phase, A leakage circuit, comprising: a protection circuit that opens the main circuit contact when the detection voltage of the voltage detection circuit becomes equal to or higher than a reference voltage or when the leakage detection circuit detects a ground fault current. vessel. 2. The earth leakage breaker according to claim 1, wherein the plurality of rectifying elements are housed inside the terminal block. 3. A circuit breaker having a protection function for the earth leakage circuit breaker according to claim 1 or 2.