JP7819643B2 - circuit breaker - Google Patents

Description

The present invention relates to a circuit breaker that can be used as a molded case circuit breaker or an earth leakage circuit breaker.

Known circuit breakers for low-voltage power distribution systems include molded-case circuit breakers with overcurrent protection and earth fault circuit interrupters with overcurrent and ground fault protection. These molded-case circuit breakers and earth fault circuit interrupters are equipped with arc extinguishing devices that extinguish arcs that occur when the main circuit contacts (fixed and movable contacts) perform an interruption operation (see, for example, Patent Document 1 for a conventional earth fault circuit interrupter and Patent Document 2 for a conventional molded-case circuit breaker).

Patent No. 5866993 Japanese Patent Application Laid-Open No. 2004-273339

The earth leakage circuit breaker of Patent Document 1 is structured so that the printed circuit board of the earth leakage detection circuit mounted on the main body case is provided with a shielding section inside the main body case that shields the arc extinguishing device from the earth leakage detection circuit and prevents the inflow of arc gas, so that soot contained in the arc gas generated by the arc extinguishing device does not flow. On the other hand, the molded case circuit breaker of Patent Document 2 does not have any parts that prevent contact with arc gas, and therefore, unlike the main body case of the earth leakage circuit breaker of Patent Document 1, it is structured without a shielding section. As such, it is not possible to share the main body case between earth leakage circuit breakers and molded case circuit breakers, which poses a problem in terms of manufacturing costs.

The present invention aims to provide a circuit breaker that can reduce manufacturing costs by using common components for part of the main body case of the earth leakage breaker and molded case breaker.

To achieve the above object, one aspect of the present invention provides a circuit breaker in which a main circuit contactor, an opening/closing mechanism, an arc extinguishing device, an overcurrent tripping device, a zero-phase current transformer, a trip coil unit, and a printed circuit board for a ground fault detection circuit are mounted inside a main body case consisting of a first case and a second case; the first case is provided with a partition wall that separates a first internal space in which the arc extinguishing device and main circuit contactor are located from a second internal space in which other components are located; a portion of the partition wall is formed with an access hole that connects the first internal space with the second internal space; a blocking means is provided on the trip coil unit; the trip coil unit is mounted on the partition wall on the second internal space side; and the access hole is blocked by the blocking means.

With the circuit breaker of the present invention, the first case of the main body case can be used as a common component for both the earth leakage breaker and the molded case breaker, thereby reducing manufacturing costs.

1 is a perspective view showing a molded case circuit breaker according to the present invention with a portion of the main body case removed; 1 is a cross-sectional view showing a circuit structure of one phase of a molded case circuit breaker according to the present invention. FIG. 2 is a perspective view showing the appearance of an auxiliary switch as an accessory device mounted on the molded case circuit breaker. 1 is a perspective view showing an earth leakage breaker according to the present invention with a part of the main body case removed; 1 is a cross-sectional view showing a circuit structure of one phase of an earth leakage breaker according to the present invention; FIG. 2 is a perspective view showing the appearance of a trip coil unit mounted on the earth leakage breaker. 3 is a cross-sectional view showing a state in which a trip coil unit mounted on an earth leakage breaker is sandwiched between a first case and a second case. FIG.

Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following explanation. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

Furthermore, the embodiments shown below are examples of devices and methods that embody the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

The circuit breaker shown in Figure 1 is a three-phase (R, S, T) AC molded-case circuit breaker 1 connected between the power supply side and load side of the main circuit, and is shown with part of the main body case 2 removed.

The main body case 2 has a divided structure consisting of a lower case 3, a power supply side intermediate case 4, a load side intermediate case 5, and an upper cover 6 that is rotatably connected to the load side intermediate case 5.

The lower case 3 is fitted with a switching mechanism 7 that opens and closes the main circuit contacts (fixed and movable contacts, not shown), an operating handle 8 that operates the switching mechanism 7, an overcurrent trip device 9 that causes the switching mechanism 7 to trip when an overcurrent flows in the main circuit, main circuit conductors 13 corresponding to the R, S, and T phases, an arc extinguishing device 14 that extinguishes the arc that occurs when the main circuit contacts perform an interruption operation, and an auxiliary switch unit 15 as an accessory device that detects the on/off state of the R-phase and T-phase main circuit contacts.

In Figure 1, the auxiliary switch unit 15 is shown as being mounted on the lower case 3, but in reality, as shown in Figure 2, the auxiliary switch unit 15 is stored in the accessory device storage section 12 provided in the power supply side intermediate case 4, which will be described later.

Figure 2 is a cross-sectional view of the molded case circuit breaker 1 along the R phase. The main body case 2 is assembled by tightening screws with the power supply side intermediate case 4 and load side intermediate case 5 overlapping the lower case 3. The upper cover 6 overlaps the power supply side intermediate case 4 and load side intermediate case 5 and is hingedly connected to the load side intermediate case 5. The power supply side main circuit terminal 13a and the load side main circuit terminal 13b, which constitute the main circuit conductor 13, are fixed to the lower case 3. Reference numeral 16 in Figure 2 denotes a contact holder, which supports the movable contact of the main circuit contact. Rotation of this contact holder 16 opens and closes the movable contact relative to the fixed contact.

Figure 3 shows the shape of the auxiliary switch unit 15, which includes a switch body 15a, a fixed portion 15b provided on one side of the switch body 15a, and a detection lever 15c protruding from the opposite side of the fixed portion 15b of the switch body 15a.

As shown in Figure 2, the power supply side intermediate case 4 has a partition wall 17 that separates the first internal space S1, in which the arc extinguishing device 14 and contact holder 16 are located, from the second internal space S2, in which the switching mechanism 7 and overcurrent tripping device 9 are located. The surface of the partition wall 17 closest to the switching mechanism 7 serves as the accessory device installation section 17a of the accessory device storage section 12, and a circular access hole 18 is formed near the accessory device installation section 17a, penetrating to the contact holder 16 side.

The auxiliary switch unit 15 is positioned by placing the switch body 15a on the accessory installation section 17a, and placing the detection lever 15c, which has passed through the access hole 18, in contact with the contact holder 16. The upper cover 6 then presses the fixed portion 15b toward the accessory installation section 17a, fixing the auxiliary switch unit 15 to the accessory storage section 12 of the power supply side intermediate case 4. When the detection lever 15c is operated by rotating the contact holder 16, the switch body 15a detects the on/off state of the main circuit contact.

In the molded case circuit breaker 1 configured as described above, when an overload current flows through the main circuit, the overcurrent trip device 9 performs a tripping operation, causing the switching mechanism 7 to trip and separate the movable contact of the main circuit contact from the fixed contact. At this time, an arc is generated between the movable contact of the movable contact and the fixed contact of the fixed contact, but the arc comes into contact with the grid 14a of the arc extinguishing device 14, where it is broken, cooled, and extinguished.

In this embodiment, the molded-case circuit breaker 1 is equipped with an auxiliary switch unit 15 in the accessory device installation section 17a of the accessory device storage section 12, but an alarm switch may also be installed.

Next, the circuit breaker shown in Figure 4 is a three-phase (R, S, T) AC earth leakage breaker 20 connected between the power supply side and load side of the main circuit, and is shown with part of the main body case 2 removed.

The main body case 2 of the earth leakage circuit breaker 20 shares the lower case 3 and power supply side intermediate case 4 used in the molded case circuit breaker 1 of the first embodiment, and also includes a load side intermediate case 21 and upper cover 22 that are dedicated to the earth leakage circuit breaker 20.

As shown in Figure 4, the main case 2 contains an opening/closing mechanism 7, an operating handle 8, an overcurrent trip device 9, a main circuit conductor 13, an arc extinguishing device 14, an auxiliary switch unit 15 arranged in the T-phase main circuit, a zero-phase current transformer 23 that detects unbalanced current in the main circuit using the R-, S-, and T-phase main circuits as primary conductors, and a trip coil unit 24 arranged in the R-phase main circuit. Furthermore, as shown in Figure 5, the trip coil unit 24 is equipped with a printed circuit board 25 on which circuit components for a leakage detection circuit that detects the occurrence of a ground fault current from the secondary output level of the zero-phase current transformer 23 are mounted.

In Figure 4, the auxiliary switch unit 15 and trip coil unit 24 are shown as being mounted in the lower case 3, but in reality, as shown in Figure 5, the trip coil unit 24 is housed in the accessory device storage section 12 provided in the power supply side intermediate case 4. Although not shown, the auxiliary switch unit 15 is also housed in the accessory device storage section 12 provided in the power supply side intermediate case 4.

As shown in Figure 5, the partition wall 17 of the power supply side intermediate case 4 separates the first internal space S1, in which the arc extinguishing device 14 and contact holder 16 are located, from the second internal space S2, in which the switching mechanism 7, overcurrent tripping device 9, zero-phase current transformer 23, and printed circuit board 25 of the leakage detection circuit are located.

The trip coil unit 24 is a device that receives an output signal from the earth leakage detection circuit and trips the opening/closing mechanism 7. In Figure 6, the left side shows the bottom side of the trip coil unit 24. The trip coil case 26 has an arm 27 protruding from one side, and an annular screw-through portion 28 is formed at the tip of the arm 27. In addition, a cylindrical protruding access hole blocker 29 is formed on the bottom surface of the trip coil case 26.

As shown in Figure 5, the trip coil unit 24 is mounted with the bottom of the trip coil case 26 on the accessory installation section 17a of the power supply side intermediate case 4, and the access hole closure section 29 formed on the bottom is fitted into the access hole 18 provided near the accessory installation section 17a. Also, as shown in Figure 7, the threaded through section 28 of the trip coil unit 24 is penetrated by a fastening screw 30 that fastens the load side intermediate case 21, power supply side intermediate case 4, and lower case 3, and is fixed in place between the load side intermediate case 21 and power supply side intermediate case 4.

In the earth leakage circuit breaker 20 configured as described above, when a ground fault current flows in the main circuit, the zero-phase current transformer 23 detects the occurrence of a ground fault current and the earth leakage detection circuit sends an output signal to the trip coil unit 24. The trip coil unit 24 then trips the switching mechanism 7, separating the movable contact of the main circuit contact from the fixed contact. At this time, an arc is generated between the movable contact of the movable contact and the fixed contact of the fixed contact, but the arc comes into contact with the grid 14a of the arc extinguishing device 14, is broken, cooled, and extinguished.

Here, the access hole 18 provided near the accessory device installation section 17a of the power supply side intermediate case 4 is blocked by fitting an access hole blocking section 29 provided on the trip coil unit 24 into it. Since the first internal space S1, in which the arc extinguishing device 14 and contact holder 16 are located, and the second internal space S2, in which the leakage detection circuit printed circuit board 25 is located, are separated by a partition wall 17, arc gas generated by the arc extinguishing device 14 does not flow to the printed circuit board 25.

In addition, the generation of arc gas increases the internal pressure in the first internal space S1, and the internal pressure of the arc gas acts on the access hole closure portion 29 fitted into the access hole 18 in a direction that causes it to escape through the access hole 18. However, because the threaded through portion 28 of the trip coil unit 24 is fixed in a sandwiched state between the load side intermediate case 21 and the power supply side intermediate case 4 via the supply screw 30, it is possible to reliably prevent the access hole closure portion 29 from escaping through the access hole 18.

In the earth leakage circuit breaker 20 of this embodiment, the access hole 18 provided in the accessory installation section 17a of the power supply side intermediate case 4 is blocked by fitting the access hole blocking section 29 of the trip coil unit 24 into it, and the first internal space S1 in which the arc extinguishing device 14 and contact holder 16 are located is separated from the second internal space S2 in which the printed circuit board 25 of the earth leakage detection circuit is located by the partition wall 17, so that arc gas generated by the arc extinguishing device 14 does not flow to the printed circuit board 25. Therefore, in the earth leakage circuit breaker 20 of this embodiment, soot contained in the arc gas does not adhere to the circuit of the printed circuit board 25, improving the insulation performance of the printed circuit board 25.

In addition, in the earth leakage circuit breaker 20 of this embodiment, the threaded through-hole 28 of the trip coil unit 24 is fixed in a sandwiched state between the load side intermediate case 21 and the power supply side intermediate case 4 via the supply screw 30. This reliably prevents the access hole blocking portion 29 from slipping out of the access hole 18 even if the internal pressure of the first internal space S1 increases due to the generation of arc gas.

Furthermore, the lower case 3 and power supply side intermediate case 4 that make up the main body case 2 are used as common components for the molded case circuit breaker 1 and the earth leakage circuit breaker 20, which helps reduce manufacturing costs.

1 Molded-case circuit breaker 2 Main body case 3 Lower case (first case)
4 Power supply side intermediate case (first case)
5 Load side intermediate case (second case)
6 Upper cover (second case)
7 Opening and closing mechanism 8 Operating handle 9 Overcurrent tripping device 12 Accessory device storage section 13 Main circuit conductor 13a Power supply side main circuit terminal 13b Load side main circuit terminal 14 Arc extinguishing device 14a Grid 15 Auxiliary switch unit (accessory device)
15a Switch body 15b Fixed part 15c Detection lever (accessory)
16 Contact holder 17 Partition wall 17a Accessory device installation section 18 Access hole 20 Earth leakage breaker 21 Load side intermediate case (second case)
22 Upper cover (second case)
23 Zero-phase current transformer 24 Trip coil unit 25 Printed circuit board 26 Trip coil case 27 Arm portion 28 Screw-through portion 29 Access hole closing portion 30 Supply screw S1 First internal space S2 Second internal space

Claims (3)

A circuit breaker in which a main circuit contact, a switching mechanism, an arc extinguishing device, an overcurrent tripping device, a zero-phase current transformer, a trip coil unit, and a printed circuit board for a leakage detection circuit are mounted inside a main body case consisting of a first case and a second case,
The first case is provided with a partition wall that separates a first internal space in which the arc extinguishing device and the main circuit contact are arranged from a second internal space in which other components are arranged, and an access hole that communicates the first internal space with the second internal space is formed in a part of the partition wall,
a blocking means provided in the trip coil unit, the trip coil unit being mounted on the partition wall on the second internal space side, and the access hole being blocked by the blocking means. The circuit breaker of claim 1, characterized in that the blocking means comprises a protruding access hole blocking portion provided on a portion of the trip coil case of the trip coil unit, and when the trip coil unit is mounted on the partition wall, the access hole blocking portion fits into and blocks the access hole. The trip coil case has a screw-through portion formed integrally therewith,
3. The circuit breaker according to claim 2, wherein when the first case and the second case are fixed together with a fastening screw, the screw-through portion through which the fastening screw passes is clamped between the first case and the second case.