JPS6352419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an instantaneous tripping device for a circuit breaker or breaker, and more particularly to an instantaneous tripping device for a circuit breaker or breaker that can change an instantaneous tripping current value.

This type of instantaneous tripping device for circuit breakers and disconnectors is used to protect electric motors and high voltage fuses.
There is a demand for a device that can change the instantaneous tripping current value over a wide range and that operates with high precision relative to the set value.

An example of a conventional instantaneous tripping device for a circuit or disconnector is shown in FIG. 1 is a fixed core formed by bending a magnetic plate into a U-shape, and 2 is a movable core arranged at a predetermined distance G on the opening side of the U-shaped fixed core 1. 3 is a conductor, and the conductor 3 suddenly rises along the bottom of the U-shaped frame of the fixed core 1, is bent into an inverted U shape, and is connected between the fixed core 1 and the movable core 2. This conductor 3 constitutes a magnetic circuit.
When a current exceeding a set value flows through the movable core 2, the movable core 2 is attracted to the fixed core 1 against the spring force of the spring 4, which activates the tripping claw 5 of the tripping device to close the circuit or break the circuit. Opens the circuit instantly. In this tripping device, when changing the setting of the instantaneous tripping current value, it is carried out by changing the gap G between the fixed iron core 1 and the movable iron core 2 using an adjustment means (not shown). 6 is a case in which the fixed iron core 1 is attached.

However, such conventional instantaneous tripping devices for circuits and disconnectors have the following problems.

(1) The attraction characteristics between the attraction force of the fixed core to the movable core (hereinafter simply referred to as attraction force) and the gap size G have a relationship as shown in Figure 2.
As the size G of the air gap increases, the attraction characteristic curve becomes saturated, and it is impossible to set the setting value of the tripping current to I3, for example. In other words, in this type of breaker which sets the tripping current value by changing the air gap G, the setting of the tripping current value has conventionally been limited to an extremely small range of the air gap size G. Ta. Therefore, a slight difference in the gap G may cause a large error in the tripping current value.

(2) Since the suction force is relatively large, the spring constant of the return spring is large, and when changes in the deflection of the movable iron core 3 are taken into consideration, a spring load with a higher precision is required, which increases the cost.

(3) As shown in Figure 2, the straight line A-A, which indicates the characteristics of the return spring, has a downward trend to the right, and B-B
There is no upward trend to the right as shown by the line (it is impossible for the force to become weaker the more the spring is stretched). Therefore, the adjustable range is naturally determined by the suction characteristic curve of the instantaneous tripping device, and it has been difficult to expand the adjustable range.

The purpose of the present invention is to solve these problems, further expand the adjustable range of the instantaneous tripping current value with a simple structure, further improve the accuracy of the set current value, and provide a circuit that can be obtained at a low cost. An object of the present invention is to provide an instantaneous tripping device for a disconnector.

In order to achieve such an object, the present invention includes a fixed iron core and a movable iron core that forms a magnetic circuit between the fixed iron core, and when tripping, the magnetic attraction force generated by the magnetic flux of the magnetic circuit causes In instant tripping devices for circuit breakers and disconnectors, the movable core is attracted to the fixed core against the spring force of a return spring that has one end hooked to the movable core, and is fixed to a part of the fixed core. An auxiliary core that shunts a part of the magnetic flux passing through the core is provided, and the magnetic poles of the auxiliary core and the magnetic poles of the fixed core are placed opposite to each other with the movable core in between, and the magnetic attraction force generated between the fixed core and the movable core is This feature is characterized in that a part of the magnetic attraction force generated between the auxiliary iron core and the movable iron core is canceled out.

Therefore, according to the instantaneous tripping device for circuit breakers and breakers configured as described above, the attractive force generated by the magnetic flux of the magnetic circuit formed between the movable core and the auxiliary core is applied to the movable core and the fixed core. Since it acts to cancel the attractive force generated by the magnetic flux of the magnetic circuit formed between the fixed core and the movable core, the attractive force characteristics can be maintained without saturating even in a relatively large area of the gap between the fixed core and the movable core. The adjustment range of the instantaneous tripping current value can be expanded.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 shows an embodiment of the invention. The first below
The explanation will be continued by assigning the same reference numerals to the same parts as in the figures. Here, 7 is an auxiliary iron core made of a magnetic plate,
As shown in FIGS. 4A and 4B, it is formed so as to surround the U-shaped shape of the iron core 1, and its tip portions 7A are bent in directions facing each other. The iron core 1 and the auxiliary iron core 7 are attached using, for example, spot welding. Reference numeral 8 denotes a protrusion protruding from the case 4, which brings the end of the movable core 2 into contact with each other in the normal energized state (see Fig. 4B), and connects the movable core 2 and the auxiliary core tip 7A. A predetermined air gap GA is maintained in between.
Note that in this state, a predetermined gap GB is maintained between the fixed iron core 1 and the movable iron core 2.

In the instantaneous tripping device configured in this way,
When a current flows through the conductor 3, as shown in FIG. 4B, a main magnetic flux φ1 passing through the fixed iron core 1 and the movable iron core 2 and a sub-magnetic flux φ2 passing through the auxiliary iron core 7 and the movable iron core 2 are generated. As a result, an attractive force F1 due to the main magnetic flux φ1 and an attractive force F2 in opposing directions due to the sub magnetic flux φ2 are generated in the movable iron core 2. In the area where the air gap GB between fixed core 1 and movable core 2 is small, main magnetic flux φ1 becomes sub-magnetic flux φ2
Since it is considerably larger than that, the attraction force characteristics of the movable iron core 2 are almost the same as normal attraction force characteristics. However, in a region where the air gap GB is large, the proportion of the sub magnetic flux φ2 passing through the movable iron core 1 and the auxiliary iron core 7 increases, and the attractive force F2 also increases, so the attractive force F2 acts as a braking force for the attractive force F1.

In other words, in circuit breakers and breakers with this type of structure,
Since there is little leakage of magnetic flux to the outside, stable attractive force characteristic curves as shown by the broken line in FIG. 2 and the solid line in FIG. 5 can be obtained as the value of the difference in attractive force (F1-F2). Therefore, it is possible to use up to the gap G3 at the cross point C3 (see Fig. 5) where the load of the return spring 4 and the attractive force against the movable core 2 are equal, and the tripping current value can be changed from I2 to I3.
It can be expanded to. When setting the cross-sectional area of the auxiliary core 7, make it smaller than the cross-sectional area of the fixed core 1 (see Figure 4B) so that it is magnetically saturated in a relatively large current region exceeding I3. Select to do so.

FIG. 6 shows another embodiment of the present invention, in which the fixed iron core 1 and the auxiliary iron core 7 are integrally constructed. The other configurations are the same as in FIG. 3.

As described above, according to the present invention, an auxiliary core that shunts a part of the magnetic flux passing through the fixed core is provided in a part of the fixed core, and the magnetic poles of the auxiliary core and the magnetic poles of the fixed core are connected to the movable core. The magnetic attraction force generated between the fixed core and the movable core is partially canceled out by the magnetic attraction force generated between the auxiliary core and the movable core, which improves the attractive force characteristics. The adjustment range of the instantaneous tripping current value can be expanded without saturation in a relatively large area of the gap between the fixed core and the movable core. Also,
Since the cross point between the return spring load curve and the attraction force characteristic curve can be set to avoid the saturation region, the accuracy of picking up the instantaneous tripping current value is improved. Furthermore, the present invention has a simple structure called an auxiliary core, and can be manufactured relatively inexpensively. Furthermore, since the adjustable range of the instantaneous tripping current value can be expanded, protection coordination in the power distribution system can be made more effective.

It goes without saying that the present invention can be applied to instantaneous tripping devices for circuits and disconnectors such as electric leakage disconnectors, low pressure air disconnectors, and disconnectors.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of the configuration of a conventional instantaneous tripping device for circuit breakers, and Figure 2 is a gap G between the fixed core and the movable core that generates the suction force of the movable core.
FIG. 3 is a cross-sectional view showing an example of the configuration of the instantaneous tripping device for a circuit breaker according to the present invention;
Figure 4A is a perspective view of the fixed core and auxiliary core;
FIG. 4B is a cross-sectional view including the fixed core, movable core, auxiliary core, and protrusions; FIG. 5 is a characteristic curve diagram of the attraction force of the movable core versus the gap G between the fixed core and the movable core; FIG. 6 is a perspective view of a fixed core and an auxiliary core according to another embodiment of the present invention. 1...Fixed core, 2...Movable core, 3...Conductor, 4...Spring, 5...Trip claw, 6...Case, 7...Auxiliary core, 7A...Tip, 8...Protrusion Department.

Claims (1)

[Scope of Claims] 1. It has a fixed iron core and a movable iron core that forms a magnetic circuit between the fixed iron core, and when tripping, due to the magnetic attraction force generated by the magnetic flux of the magnetic circuit,
In the instantaneous tripping device for a circuit breaker, wherein the movable core is attracted to the fixed core against the spring force of a return spring that has one end hooked to the movable core, the fixed core An auxiliary core that shunts a part of the magnetic flux passing through the fixed core is provided in a part of the fixed core, and magnetic poles of the auxiliary core and magnetic poles of the fixed core are arranged opposite to each other between the movable core and the fixed core and the movable core. An instantaneous tripping device for a circuit breaker, characterized in that a part of the magnetic attraction force generated between the auxiliary iron core and the movable iron core is canceled by the magnetic attraction force generated between the auxiliary iron core and the movable iron core. .