JPH0129007B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to circuits and disconnectors,
In particular, it relates to circuit breakers that open a movable element using electromagnetic repulsion between conductors and limit the current when a large current such as a short circuit current flows, prior to driving an automatic tripping device. be.

FIG. 1 is a partial side view of a conventional circuit breaker. In FIG. 1, a stator 1 is formed in a U-shape and is fixed to, for example, a base (not shown).
The fixed contact 2 is attached to one end of the stator 1. The movable contact 3 is attached to one end of the movable element 4 opposite to the fixed contact 2. The pin 5 rotatably attaches the other end of the movable element 4 to one end of the movable element frame 6. The shaft 7 is fixed to the other end of the movable frame 6, and rotates itself to rotate the movable frame 6. The torsion spring 8 is wound around the pin 5, one end 801 of which is engaged with the shaft 7, and the other end 802 which is engaged with the movable element 4 and presses the movable element 4. The flexible conductor 9 connects the armature 4 to a tripping device (not shown).

Next, this operation will be explained using FIGS. 2 and 3. In FIG. 1, current flows through stator 1 → fixed contact 2 → movable contact 3 → mover 4 → flexible conductor 9. During normal manual opening and opening using a tripping device (not shown) at the time of a small overcurrent, a rotational force is applied to the shaft 7 by the operation of the opening/closing mechanism (not shown), and the shaft 7 becomes the center of rotation. The child frame 6 and the movable element 4 rotate counterclockwise and enter the open state shown in FIG. 2. Next, if a large short circuit current flows,
The movable element 4 is caused by the repulsive force between the contacts caused by current concentration at the contact point between the fixed contact 2 and the movable contact 3, and the electromagnetic repulsive force caused by the oppositely directed currents flowing through the stator 1 and the movable element 4, which face each other. Prior to the operation of the opening/closing mechanism (not shown), the opening/closing mechanism (not shown) rapidly rotates counterclockwise about the pin 5 and enters the open state shown in FIG. Therefore, the arc generated between the fixed contact 2 and the movable contact 3 is extended, and together with the effect of an arc extinguisher (not shown) using the effect of a de-ion grid, etc., this increases the arc voltage and limits the large short circuit current. It washes away and comes to a standstill.

However, in conventional circuit breakers, as is clear from the difference in the state of the torsion spring 8 shown in FIGS. Due to the rotation, the clockwise pressing force of the torsion spring 8 on the movable element 4 also increases, so that the effective electromagnetic repulsive force acting on the movable element 4 is reduced. That is, while the electromagnetic repulsion force decreases as the movable element 4 rotates counterclockwise, the torsion spring 8 decreases as the movable element 4 rotates counterclockwise.
Since the clockwise pressing force on the movable element 4 becomes large, the rotation speed of the movable element 4 in the counterclockwise direction becomes slow, the rise rate of the arc voltage is small, and the current limiting effect is reduced. .

This invention was made to eliminate the drawbacks of the conventional ones as described above, and the moment due to the torsion spring 3 that presses the mover 4 in the clockwise direction is
The purpose is to reduce the amount as the movable element 4 rotates in the counterclockwise direction, increase the rotation speed of the movable element 4, and provide a circuit or disconnector with a greater current limiting effect. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a partial side sectional view showing an embodiment of the circuit breaker according to the present invention. In the drawings, parts that are the same or corresponding to those in FIGS. 1 to 3 are denoted by the same reference numerals or dashes. The spring pin 10 is located closer to the movable contact 3 than the shaft 7 of the movable frame 6 and above the shaft 7. The spring hook pin 11 is provided closer to the movable contact 3 than the pin 5 of the movable element 4 and above the pin 5 on substantially the same horizontal line as the upper end of the shaft 7. The torsion spring 8' is wound around a spring pin 10, one end 801 of which is secured to the upper end surface of the shaft 7, and the other end 802 to the spring pin 11.

Next, this operation will be explained using FIGS. 5 to 7. In Fig. 4, when the circuit is opened manually manually and when the circuit is opened by a tripping device (not shown) at the time of a small overcurrent, a rotational force is applied to the shaft 7 by the operation of the opening/closing mechanism (not shown), and the shaft 7 is opened. The movable frame 6 and the movable element 4 rotate counterclockwise as a center of rotation,
The circuit becomes open as shown in FIG. Next, when a large short-circuit current flows, there is a repulsive force between the contacts that occurs due to current concentration at the contact point between the fixed contact 2 and the movable contact 3, and an opposite force that flows between the stator 1 and the movable element 4, which are facing each other. Due to the electromagnetic repulsive force caused by the current in the direction, the mover 4 rapidly rotates counterclockwise around the pin 5 prior to the operation of the switchgear (not shown), and enters the open state shown in FIG. 6. Become. Pin 5 of the spring-loaded pin 11 in the closed circuit state shown in FIG. 4 and in the open circuit state shown in FIG.
FIG. 7 shows the change in position relative to the spring pin 10.

In FIG. 7, the solid line indicates the positional relationship between the spring hook pin 11 and the torsion spring 8' in the closed circuit state shown in FIG. ′ is shown.
The moment M ₁ of the torsion spring 8' pressing the mover 4 shown in the solid line in FIG. 7 and the moment M ₂ pushing the mover 4 of the torsion spring 8' shown in the dashed line in FIG. 7 are expressed by the following equation. expressed.

M ₁ =Kθ ₁ /l ₁ ×L ₁ [1] M ₂ =K−θ ₂ /l ₂ ×L ₂ [2] where, K: Spring constant of torsion spring 8' θ ₁ : Closed circuit state of mover 4 Deflection angle of the torsion spring 8' at the time θ ₂ : The torsion spring 8' at the time of repulsion of the mover 4
Angle of deflection L ₁ : Distance between the vertical line drawn from the other end 802 of the torsion spring 8' to the pin 5 and the spring hook pin 11 when the mover 4 is in a closed circuit state L ₂ : Torsion spring when the mover 4 is repulsive Distance between the vertical line drawn from the other end 802 of 8' to pin 5 and spring-loaded pin 11 l ₁ : Arm of twist spring 8' that presses spring-loaded pin 11 when movable element 4 is in the closed circuit state Length l ₂ : Torsion spring 8' during repulsion of mover 4
is the arm length of the torsion spring 8' that pushes the spring hook pin 11. Here, the moment of repulsion of the mover 4 is
In order to make M ₂ smaller than the moment M ₁ , θ ₁
> θ ₂ , l ₁ <l ₂ , and L ₁ >L ₂ , there is no problem, but as is clear from FIG. 7, θ ₁ >θ ₂ cannot be satisfied.
Therefore, it is sufficient that the relationship (θ ₂ /θ ₁ ×l ₁ /l ₂ ×L ₂ /L ₁ )<1 [3] always holds true. However, the seventh
As is clear from the figure, the relationship (θ ₂ /θ ₁ ×l ₁ /l ₂ )>1 [4] always occurs at the beginning of rotation of the mover 4, so (θ ₂ /θ ₁ ×l ₁ / l ₂ )/(L ₁ /L ₂ )<1 [5] The positions of pin 5, spring pin 10, and spring hook pin 11, and the movable member are adjusted so that changes in L ₁ and L ₂ are significantly changed. If we configure the repulsion angle of 4 and the deflection angle of the torsion spring 8' when the mover 4 closes, then M ₁ > M ₂ , so as the mover 4 is displaced by the repulsion caused by the electromagnetic force, it will resist the change. The moment becomes smaller, and the electromagnetic repulsive force acting on the movable element 4 can be effectively utilized.

This invention is constructed as described above, and since the effective repulsive force acting on the movable element 4 becomes large, when a large short-circuit current starts flowing, the movable element 4 is
starts to rotate and the rotation speed is also large. Therefore, the arc that occurs between the movable contact 3 and the fixed contact 2 also occurs from the beginning when the large short circuit current begins to flow, the arc length increases in a very short time, the arc voltage shows a steep rise, and the large short circuit current is extremely current limited and can be easily severed.

In the above embodiment, only the movable element 4 is configured to electromagnetically repel, but the stator 1 may also be used as a movable element and both may be configured as in the above embodiment. Further, one end 801 of the torsion spring 8' may be locked to the movable frame 6, and the other end 802 of the torsion spring 8' may be directly locked to the movable element 4.

As described above, according to the present invention, the moment for applying the contact pressure of the contact point is configured to decrease as the movable element is deflected by the electromagnetic repulsion force of a large current, so that the rotation speed of the movable element is large. This has the effect that the rise of the arc voltage becomes steeper and an excellent current limiting effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial side view of a conventional circuit breaker, FIGS. 2 and 3 are explanatory diagrams of the operation of FIG. 1, and FIG. 4 is an embodiment of the circuit breaker according to the present invention. The partial side views shown in FIGS. 5 to 7 are explanatory diagrams of the operation of FIG. 4. In the figures, the same parts or equivalent parts in each figure are denoted by the same symbols or the same symbols with a dot. 1 is a stator, 2 is a fixed contact, 3 is a movable contact, 4 is a mover, 5 is a pin, and 6 1 is a movable frame, 7 is a shaft, 8' is a torsion spring, 801 is one end, 802 is the other end, 10 is a spring pin, and 11 is a spring hook pin.

Claims (1)

[Claims] 1 A pair of conductors, which are movers, each having opposing contacts at one end and repelling each other due to the electromagnetic force of the current flowing through each, so that at least one of the conductors separates from the other, the other end of the mover being connected to a pin. Therefore, a movable frame rotatably supported at one end; a shaft fixed to the movable frame and rotating the movable frame by its own rotation;
a spring pin provided on the movable frame; and a spring pin wound around the spring pin, one end of which is locked to the shaft or the movable frame, and the other end of which is locked to the mover directly or via a spring hook pin. 1. A circuit breaker comprising a torsion spring and configured to reduce a pressing moment of the torsion spring acting on the movable element during electromagnetic repulsion of the movable element.