JPH0126140B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current limiting device that limits the current in an electrical circuit by passing an arc generated by opening of both contacts that have closed an electrical circuit through an arc path in a narrow gap.

When a short-circuit accident occurs in an electric circuit, it is necessary to quickly disconnect the circuit and take recovery measures, and the larger the power supply capacity, the larger the fault current. By the way, in the conventional AC switchgear, the fault current continues to flow until the current zero point, and the electric circuit equipment is required to have the ability to withstand the fault current during that time. For this reason, large-capacity equipment, especially switchgear, is required, and this increase in capacity poses an obstacle to large-scale power system design. On the other hand, in DC circuits, there is no current zero point like in AC, so the arc voltage is increased to the same level as the circuit voltage to reduce the current and then break. This ability of disconnectors was inadequate, and they could only disconnect circuits with voltages of several thousand volts, which was an obstacle to the development of high-voltage DC power transmission.

In order to solve this problem, the arc generated by the opening of the contact that has closed the electric circuit is extended through the narrow arc path formed by the opposing surfaces of the insulating member, thereby increasing the arc voltage and limiting the current. Accordingly, prior art current limiting devices have been developed to facilitate shearing.

This prior art current limiting device is shown in longitudinal section in FIG. 1, which shows the closed state. 1 is a fixed electrode electrically connected to one terminal plate (not shown); 2 is a fixed contact provided on the inner diameter of the front side of the fixed electrode; and 3 is the front of the outer diameter of the fixed electrode 1. An insulating outer cylinder 4 has a large inner diameter part fitted and fixedly supported on the side and a small inner diameter part on the front side, 4 is an insulated inner rod fitted and fixed to the fixed electrode 1, and the outer diameter part on the front side is an insulated outer cylinder 3. An arc passage 5 which is elongated to a predetermined length in the longitudinal direction with a narrow gap t ₁ between the two is formed opposite to the small inner diameter portion of the arc passage 5 . Reference numeral 6 denotes a movable contact that is moved in and out in the direction of arrow A by a drive device (not shown), and has a shaft hole 6a on the tip side for covering the insulating inner rod 4 with a slight gap. The outer diameter portion passes through the small inner diameter portion of the insulating outer cylinder 3 through a slight gap, and is inserted into the fixed contact 2 to make electrical contact.

In the above device, when in the input state shown in Fig. 1,
When the movable contact 6 moves apart in the direction of the arrow A in the shriveling operation, both the contacts 2 and 6 are separated and an arc 7 is generated between them, as shown in FIG. This arc 7 passes through the arc passage 5 and is extended.
It is narrowed and elongated to a small cross-sectional area by the slit _t1 . In this way, the arc resistance increases, the arc voltage increases, the fault current is limited, and damage to system equipment due to overcurrent is prevented.

In the case of an AC circuit whose power supply capacity is not large, it is possible to break the circuit at the current zero point using only the device according to the prior art described above. In addition, AC circuits with large power supply capacity,
Alternatively, in the case of a DC circuit, the fault current limited as described above can be easily cut off by a relatively small capacitance cutter connected in series.

However, in the apparatus shown in FIG. 1, the arc 7 raises the temperature of the gas in the arc passage 5, and if the pressure rises extremely, there is a risk that the insulating outer cylinder 3 will be damaged. Therefore, increasing the wall thickness of the insulating outer cylinder results in a larger external shape.

This invention relates to one and the other contacts whose contact is closed and opened by relative movement in the longitudinal direction, and an inner insulating member and an outer insulating member which surround an arc generating part from the inside and outside due to the opening and closing of both contacts. an insulating member, the outer insulating member passes through the other contact so as to be relatively movable in the longitudinal direction;
An arc path of a predetermined length in the longitudinal direction is formed between the outer insulating members with a narrow gap along the relative movement path of the other contact, and the arc generated by the opening of both the contacts is connected to the arc. In a device that limits the circuit current by stretching it in a passage, the outer insulating member is cut in multiple places in the circumferential direction from the arc passage side to the outer periphery at the same position in the relative movement direction of the contact, so that outside air can be A communication groove with a groove width larger than the slit size of the arc passage is provided to guide the arc from the arc passage, cool it, and release high pressure gas generated in the arc passage to cool the insulating member. Prevents damage and reduces external size.
By inviting the arc into the communication groove and increasing the arc length, increasing the electrical resistance and increasing the cooling effect,
The object of the present invention is to provide a current limiting device with significantly improved current limiting performance.

FIG. 3 is a longitudinal sectional view of a current limiting device according to an embodiment of the present invention, showing a state in which 1, 2, 4
6 and 6a are the same as the devices of the prior art described above, and their explanation will be omitted. Reference numeral 10 denotes an insulating outer cylinder having a large inner diameter part fitted and fixed to the front side of the outer diameter part of the fixed electrode 1, and having a small inner diameter part on the front side, and between the small inner diameter part and the outer diameter part of the insulating inner rod 4. An arc passage 5 having a predetermined length in the longitudinal direction is formed in the gap _t1 . This insulation outer cylinder 1
0, arc passage 5 (forms the arc generation site)
A longitudinal communication groove 10a that is cut through the outer circumference from the side and communicates with the outside is formed between the fixed contact 2 and the movable contact 6.
A plurality of locations are provided in the circumferential direction at the same position in the direction of relative movement. This communication groove 10a
As shown in the cross-sectional view in FIG. 4, the groove width t ₃ is made larger than the slit t ₁ of the arc passage 5.

In the device shown in FIG. 3, when the movable contact 6 in the closing state shown by the chain line moves apart in the direction of arrow A during the cutting operation as shown by the solid line, an arc 7 occurs. this arc 7
The gas in the arc passage 5, which has become high temperature and high pressure due to the heat of Energy is removed and cooled, improving current limiting performance.

At this time, the arc 7 is divided into a plurality of communication grooves 10a and guided through it, but the width of the groove is smaller than the slit _t1.
Since t ₃ is large, the arc 7 is greatly attracted and elongated, and is cooled by good discharge of high-temperature gas and the groove wall surface of the communicating groove, further improving the current limiting effect.

FIG. 5 is a longitudinal cross-sectional view of a current limiting device according to a second embodiment of the present invention, showing a state in which it is being opened. Fixed electrode 1
1 is provided with a fixed contact 12 and an insulating outer cylinder 13
is fitted and fixed. Reference numeral 14 denotes a movable contact that is moved in and out in the direction of arrow A by a drive device (not shown), and has an insulating inner rod 15 of approximately the same outer diameter fixed to its tip. As a result of the movement, it passes through the inner diameter part of the front side of the insulating outer cylinder 13 through a narrow gap t2, and is inserted into the fixed contact ₁₂ to make electrical contact, resulting in the closed state shown by the chain line.
When the movable contactor 14 is released, the insulating inner rod 15 enters the inner diameter part of the front side of the insulating outer cylinder 13, and a narrow gap t ₂ is created between the two.
The arc passage 1 is lengthened to a predetermined length in the longitudinal direction.
6 is formed. The insulating outer cylinder 13 has a longitudinal groove 13a cut through the outer periphery from the arc passage 16 (which forms the arc generation site) and communicating outward in the direction of relative movement between the fixed contact 12 and the movable contact 14. Multiple locations are provided at the same location in the circumferential direction. The width of this communication groove is larger than the dimension of the slit _t2 , similar to that shown in FIG.

In the device shown in FIG. 5, when the movable contact 14 in the closing state shown by the chain line is moved apart in the direction of arrow A by the shrunken operation as shown by the solid line, there will be a gap between both the contacts 12 and 14. Arc 7 occurs. At this time, the insulating inner rod 15 is attached to the inner diameter part of the front side of the insulating outer cylinder 13.
enters, and the arcs 7 are separately passed through the arc passages 16 formed by both opposing surfaces and are elongated. The high-temperature, high-pressure gas in the arc passage 16 is released from the communication groove 13a in the direction of arrow B, thereby preventing damage to the insulating outer cylinder 13. Further, the arc 7 is moved from the arc passage 16 to the narrow gap
It is attracted to the communication groove 13a, which is wider than _t2 , and passes through, being greatly expanded and cooled, further improving the current limiting effect.

In addition, in the above embodiment, the number of communicating grooves is as follows:
Although there are multiple locations in the circumferential direction, there may be only one location in some cases.

Further, in the above embodiment, the fixed contact side is fixed and the movable contact side is moved, but the relationship between fixation and movability may be reversed, or both may be moved.

Furthermore, the present invention is not limited to the embodiments described above, and the present invention is not limited to the embodiments described above. It can be applied to various forms as long as it forms a narrow arc path between opposing surfaces along the movement path of the contact, and stretches the arc in this arc path to exert a current limiting function. It is possible.

As described above, according to the present invention, in extending the arc generated by the opening of both contacts to the arc path in the narrow gap between the opposing surfaces of the insulating member, the current limiting function is exerted. The outer insulating member is cut in multiple places in the circumferential direction at the same position in the relative movement direction of the contact, from the arc passage side to the outer circumference to communicate with the outside air, and the groove width is the narrow gap in the arc passage. A communication groove larger than the dimensions is provided to guide the arc from the arc passage, separate the arc,
Moreover, since the high-pressure gas emitted from inside the arc passage and the wall surface of the communication groove are cooled in each stretched state, there is no risk of damage to the outer insulating member due to a rise in gas pressure inside the arc passage. The outer shape is reduced, and the arc is separated and elongated to improve the cooling effect, and especially when used for direct current, the current limiting performance is greatly improved.

[Brief explanation of drawings]

1 and 2 are schematic longitudinal sectional views showing the current limiting device according to the prior art in the closing state and in the opening state, and FIG. 3 shows the current limiting device in the opening state according to an embodiment of the present invention. A schematic vertical sectional view, FIG. 4 is a sectional view along the - line in FIG. 3, and FIG. 5 is a second cross-sectional view of this invention.
FIG. 2 is a schematic vertical cross-sectional view showing the current limiting device according to the embodiment in a state in which it is opened. 2... Fixed contact (one contact), 4... Insulating inner rod, 5... Arc passage, 6... Movable contact (other contact), 7... Arc, 10... Insulating outer cylinder , 10a... Communication groove, 12... Fixed contact (one contact), 13... Insulating outer cylinder, 13a...
Communication groove, 14...Movable contact (other contact),
15... Insulating inner rod, 16... Arc passage. In addition,
The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. One and the other contacts that are closed and opened by relative movement in the longitudinal direction, and an inner insulating member and an outer insulating member that surround the arc generation area from the inside and outside when both contacts open and close. The outer insulating member passes the other contact so as to be relatively movable in the longitudinal direction, and a narrow gap is provided between the inner and outer insulating members along the relative movement path of the other contact. In a device in which an arc path of a predetermined length is formed in the longitudinal direction, and the arc generated by the opening of both of the contacts is stretched in the arc path to limit the circuit current, the outer insulating member is in contact with the outside insulating member. Communication grooves are provided at multiple locations in the circumferential direction at the same position in the relative movement direction of the child from the arc passage side to the outer periphery, communicating with the outside air, and having a groove width larger than the slit size of the arc passage. A current limiting device characterized by guiding an arc from an arc passage, cooling the arc, and releasing high pressure gas generated within the arc passage.