JPH03283228A - Short voltage trip gear of circuit 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] [Industrial application field]

The present invention relates to an undervoltage tripping device that is housed in a circuit breaker such as a molded case circuit breaker and trips the circuit breaker when the circuit voltage drops below a predetermined value.

[Conventional technology]

An undervoltage trip device automatically trips a circuit breaker when the circuit voltage drops, and the operating voltage is typically 70-20% of the rated voltage. This undervoltage tripping device uses an electromagnetic coil to which a circuit voltage is applied to attract a movable core against the spring force, and when the circuit voltage drops below a predetermined value, the attraction force of the electromagnetic coil becomes the spring force. It is generally known to drive the movable iron core to operate the tripping mechanism of the circuit breaker when the resistance is no longer possible, and is also described in, for example, Japanese Patent Application Laid-Open No. 57-191929.

[Problem to be solved by the invention]

Because the above-mentioned undervoltage tripping device is housed inside the circuit breaker,! Magnetic coils are inevitably required to be miniaturized, and there is a limit to the attractive force they generate and, therefore, the spring force that drives the movable core. Therefore, as described in the above-mentioned publication, a mechanism (so-called latch mechanism) that reduces the force by engaging a claw between the tripping lever and the movable iron core that acts on the tripping mechanism of the circuit breaker is usually used. ) to obtain a large tripping force with a small electromagnetic coil. However, there is a problem in that the provision of the latch mechanism complicates the structure and increases the cost of the entire device. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a small and inexpensive undervoltage tripping device for a circuit breaker that can obtain a large tripping force without using a latch mechanism.

[Means to solve the problem]

This invention achieves the above object by adding a new permanent magnet that generates a constant attractive force as a base by adding force to an electromagnetic coil whose attractive force varies depending on the circuit voltage. . In such an undervoltage tripping device, a permanent magnet is housed in a spool of a magnetic coil, and an operating rod connected to a movable core guided by the spool is coupled to a yoke into which the NWa coil is inserted. The electromagnet part protrudes through the fixed core, is rotatably supported by a base holding the electromagnet part, and is held in a reset state via the operating rod by the movable core attracted to the fixed core. The tripping lever may include a tripping lever, and a tripping spring suspended between the tripping lever and the base.

[For use]

Since the attractive force of the permanent magnet is added to the attractive force of the electromagnetic coil, the overall attractive force increases, and it becomes possible to operate a tripping spring with a large spring force using a small electromagnetic coil. Here, FIG. 3 shows the relationship between the circuit voltage and the attractive force in principle, and FIG. 3(A) shows the conventional case, and FIG. 3(B) shows the case of the present invention. As you can see from the figure, the conventional structure has 7
In the tripping range of 0 to 20% circuit voltage, only an electromagnetic coil can obtain an attractive force in the range of F, -F, but according to the present invention, an attractive force of F due to a permanent magnet is added to this. , and a suction force ranging from (FI+FM) to (F,+FM) is obtained. Therefore, with the same electromagnetic coil, the tripping spring can be made stronger by the amount of the attractive force F, and the operating stroke can be increased.

【Example】

1 and 2 show an embodiment of the present invention, and FIG. 1 (
A) is a longitudinal sectional view of the undervoltage tripping device in the suction state, (B
) is a longitudinal cross-sectional view of the circuit breaker in the tripped state, and FIG. 2 is a partially cutaway side view of the circuit breaker in which the device of FIG. 1 is housed. In the figure, 1 is a yoke consisting of a U-shaped main body 1a and a connecting piece 1b swaged across both legs of the main body 1a;
2 is a fixed core welded integrally with this, 3 is a spool inserted between yoke 1 and fixed core 2, 4 is an electromagnetic coil wound around spool 3, and 5 is the same (housed in spool 4). , a pair of permanent magnets that apply force to the electromagnetic coil 4 to generate an attractive force, 6 a movable iron core guided by the spool 3,
Reference numeral 7 indicates an operating rod that is formed integrally with the movable core 6 and projects through the fixed core 2; 8 indicates a trip lever rotatably supported by a shaft 9; and 10 indicates a view of the trip lever 8 facing toward the movable core 6. A tripping spring 11 provides a clockwise rotating force, which biases the movable core 6 toward the fixed core 2 with a spring force smaller than that of the tripping spring 10, and brings the movable core 6 into a suction state after tripping. The reset return spring 12 is a crossbar that constitutes a part of the tripping mechanism of the circuit breaker body. Figure 1 (A) where the rated voltage is applied to the electromagnetic coil 4
In this state, the movable iron core 6 stretches the tripping spring 10 by the magnetic flux of both the electromagnetic coil 4 and the permanent magnet 5, is attracted to the attraction surface 2a of the fixed iron core 2, and pulls the tripping lever 8 away from the crossbar 12. It is held in the position shown. Here, when the circuit voltage drops to 70-20% and the attractive force of the electromagnetic coil 4 decreases, the entire attractive force including the attractive force of the permanent magnet 5 becomes less than the spring force of the tripping spring 1o. , the balance between the suction force and the tripping force is lost, and the tripping lever 8 is moved by the tripping spring 10 to move the movable iron core 6 to the return spring 11.
The crossbar 12 is driven clockwise in the figure while pushing away by a stroke G against the
Move to the left in the diagram. This causes the tripping mechanism to operate and open the circuit breaker. When the circuit voltage rises to 100%, the attraction force exceeds the tripping force, and the movable iron core 6 returns to the attraction state again under the action of the return spring 11.
It becomes possible to close the circuit breaker. According to the above configuration, the attraction force is increased by the permanent magnet 5 compared to the conventional configuration using only the electromagnetic coil, and the attraction force can be directly opposed to the tripping spring 10 without using a latch mechanism, and the necessary operating stroke G can be obtained. It becomes like this. Next, another embodiment in which a mechanism for facilitating reset after circuit voltage recovery is provided will be described with reference to FIGS. 4 to 9. Note that parts corresponding to those in the embodiment shown in FIG. 1 are given the same reference numerals. First, Figure 4 shows the overall configuration of the undervoltage disconnection device,
Figure 4 (A) is a plan view, (B) is a vertical cross-sectional view, (C)
is its front view. In the figure, the electromagnet part and other components are attached to a box-shaped base 13, and this base 13 has integrally formed mounting parts 113a and 13.
b is fitted into the case 14 of the circuit breaker, and is held and fixed by a cover 15 covering the case 14 from above. The detailed configuration of the electromagnet section held by the base 13 is shown in the perspective view of FIG. In the illustrated configuration, the movable core 6 is guided by a non-magnetic cylinder 16 inserted into the spool 3, and both legs of the yoke body 1a are fitted into grooves 3a provided above and below the flange of the spool 3. The pair of upper and lower permanent magnets 5 are housed between left and right side walls 3b integrally formed on the rear flange of the spool 3, and are pressed down via a spacer 17 by a connecting piece 1b caulked to the yoke body 1a. 18 is a magnetic shunt inserted between the upper and lower permanent magnets 5. Further, the return spring 11 is inserted between the head flange 7a of the operating rod 7, which is caulked to the movable iron core 6, and the yoke main body 1a. Returning to FIG. 4, the tripping lever 8 is rotatably supported by a shaft 9 between a pair of left and right arms at the upper front surface of the base 13. As shown in FIG. Although the tripping lever 8 has an inverted shape,
As shown in FIG. 4(B), the shaft 9 passes through the bent part and the two arms 8a are long and short and are shifted in position from the front and back downward.
and 8b are formed adjacent to each other, and an arm 8c is formed toward the left side of the figure from the L-bend. Here, arm 8a
The tip of the arm 8b is opposed to the head flange 7a of the operating door 0, and the tip of the arm 8b is opposed to the crossbar 12. As shown in FIG. 4(A), a tripping spring 10 is hung between a cylindrical projection 19 formed on the side surface of the arm 8b and a cylindrical projection 20 formed on the wall surface of the base 13. On the other hand, between the pair of left and right arms at the lower front of the base 13,
A pull-back lever 21 is rotatably supported by a shaft 22,
The pull-back lever 21 is formed with an arm 21a that faces the crossbar 12 on the opposite side of the arm 8b of the pull-out lever 8. A position slightly offset from the axis 22 of the pull-back lever 21 and the tip of the arm 8c of the pull-out lever 8 are connected to each other by a connecting rod 23 whose hook-shaped ends are inserted into respective holes. has been done. In such a configuration, in the illustrated state in which the rated voltage is applied to the electromagnetic coil 4 and the movable core 6 is attracted to the fixed core 2, the tripping lever 8 is moved from the operating rod 7 via the arm 8a as shown in FIG. ) in the counterclockwise direction, tripping spring 1
0 (The arm 8b of the trip lever 8 and the arm 21a of the pull-back lever 21 are at a distance from the crossbar 12 of the circuit breaker in the closed state. When the circuit voltage decreases to 70 to 20% and the balance between the attraction force and the tripping force acting on the movable core 6 is lost as described in the embodiment shown in FIG.
The release lever 8 rotates clockwise in FIG. 4(B). FIG. 6 shows the moment when the arm 8b contacts the crossbar 12 when the tripping lever 8 rotates. As the tripping lever 8 rotates, the pulling lever 21 moves the arm 8C.
The arm 21a is rotated clockwise in the figure via the connecting rod 23, and the arm 21a approaches the crossbar 12. Next, when the arm 8b pushes the crossbar 12 to the left and moves it to a certain position, the unillustrated claw of the crossbar 12 and the latch receiver are disengaged, and the circuit breaker body with the latch released is released. The movable contact 24 is activated by the instantaneous operation of the opening/closing mechanism.
At the same time, the crossbar 12 receives a force from the opening/closing mechanism and simultaneously moves to its final position. FIG. 7 shows the state in which the tripping operation is completed in this manner. At this time, the pull-back lever 21, which had been rotating clockwise in the same way as the trip lever 8 rotated clockwise, hits the crossbar 12 moving to the left, and this time it reverses away from the crossbar 12. It is rotated counterclockwise by the force,
The tripping lever 8 is rotated counterclockwise via the connecting rod 23 against the tripping spring 10. As a result, when the circuit voltage is restored, the movable core 6 is attracted to the fixed core 2 without being hindered by the tripping spring 10, and as shown in FIG.
The tripping lever 8 can be held in a reset state. That is, according to such a configuration, re-attraction of the movable iron core 6 at the time of resetting becomes easy, and while increasing the operating stroke of the movable iron core 6, the electromagnetic coil 4 and the permanent magnet 5
It is possible to reduce the capacity of the electromagnet and to downsize the electromagnet section. FIG. 8 shows the arm 8 of the tripping lever 8 in the embodiment shown in FIG.
This shows an embodiment in which a protrusion 8d is provided integrally with C to facilitate integration into the circuit breaker main body. During installation of the tripping device, no voltage is applied to the electromagnetic coil 4 and the fixed iron core 6 is not attracted, so the tripping lever 8 is attached to the tripping spring 10 as shown in FIG. 8(A).
It is in contact with the pull-back lever 21 due to the force shown in FIG. 4. Therefore, when attempting to insert the case 14 (FIG. 4) from above, the arm 2 of the pull-back lever 21
1a hits the crossbar 12. Therefore, the 8th
As shown in Figure (B), by hooking your finger on the protrusion 8d and rotating the trip lever 8 counterclockwise, a gap is created between the pull-back lever 21 and the trip lever 8 to allow the cross bar 12 to pass through. It can be opened. FIG. 9 is a side view of a main part showing a configuration for dealing with variations in the attraction force of the electromagnet section. It is inevitable that there will be some variation between products in the attractive force generated by the electromagnetic coil 4 and the permanent magnet 5, or in the tripping force by the tripping spring 10, and as shown in FIG. 10, the operating voltage will deviate from the standard value. things can happen. Therefore, in the embodiment shown in FIG. 9, the cylindrical protrusion 20 on the base side, on which the tripping spring 10 is hooked, is provided at three locations with slightly shifted positions, so that the voltage value at which the balance between the attraction force and the tripping force is disrupted is lower than the standard value. The spring force from the tripping spring 10 can be adjusted so that it falls within the range. As described above, according to the present invention, a latch mechanism is not required, the structure is greatly simplified, and it is possible to manufacture a small and inexpensive undervoltage release device.

[Brief explanation of the drawing]

FIG. 1(A) is a vertical cross-sectional view of the embodiment of the present invention in the suction state, FIG. 1(B) is a vertical cross-sectional view of the same in the tripped state, and FIG. 2 is a circuit breaker in which the device of FIG. 1 is housed. FIG. 3(A) is a diagram showing the principle of the relationship between circuit voltage and attraction force in the conventional configuration, and FIG. 3(B) is the same (the relationship in this invention is shown). 4(A) is a plan view of another embodiment of the present invention, FIG. 4(B) is a longitudinal sectional view thereof, FIG. 4(C) is a front view thereof, and FIG. 4 is an exploded perspective view of the electromagnet section, FIG. 6 is a vertical sectional view showing the state of the circuit breaker in the embodiment shown in FIG. 4 immediately before the opening operation, and FIG. Figure 8 (A
) is an enlarged side view of the main part before installation, showing an embodiment for facilitating the installation of the device in FIG. 4 into the circuit breaker main body, FIG. This figure is an enlarged side view of a main part showing a configuration for adjusting the operating voltage of the device shown in FIG. 4, and FIG. 10 is a diagram for explaining variations in the operating voltage of the device shown in FIG. 4. 4... Electromagnetic coil, 5... Permanent magnet, 6... Movable iron core, 8... Tripping lever 10... Tripping spring,
24...Movable contact. Renowned patent attorney Yoshihide Komada z Fig.

Claims (1)

[Claims] 1) A circuit voltage is applied to an electromagnetic coil to attract the movable core against a spring force, and when the circuit voltage decreases below a predetermined value, the spring force causes the movable core to be attracted. An undervoltage tripping device for a circuit breaker that operates a tripping mechanism of a circuit breaker by driving a circuit breaker, characterized in that a permanent magnet is provided that attracts a movable core by applying force to an electromagnetic coil. Undervoltage trip device. 2) The device according to claim 1, wherein a permanent magnet is housed in a spool of an electromagnetic coil, and an operating rod connected to a movable core guided by the spool is a fixed core coupled to a yoke into which the electromagnetic coil is inserted. an electromagnet portion protruding through the electromagnet portion; and a trigger rotatably supported by a base holding the electromagnet portion, and held in a reset state via the operating rod by the movable iron core attracted to the front fixed iron core. An undervoltage trip device for a circuit breaker, comprising a release lever and a trip spring suspended between the release lever and the base.