JPH0255516A - High speed removal of short circuit - Google Patents

Abstract

PURPOSE:To prevent a device against the spreading of accident at the fault point of short circuit and development to service interruption by shorting the circuit on the load side of a fuse and by quickly reducing the current flowing to the fault point. CONSTITUTION:When a shorting fault occurs on the load side, the current +I flows to an immobile bypass conductor 11 and a magnetic field BA is generated, while to a mobile bypass conductor 12 the backward current -I flows and a magnetic field BB is generated. However, the generated field BB will hardly act on the immobile bypass conductor 11 blocked by magnetic transmitting bodies 15, so that only the mobile bypass conductor 12 will be positioned in the magnetic field due to the generated field BA between the facing edges of a cut section of the magnetic transmitting bodies 15. On that account, on the mobile bypass conductor 12 the downward force F will act which separates it from the immobile bypass conductor 11 by the current -I flowing there and the field BA. The mobile bypass contact 12a is thereby lowered downward and comes into contact with an immobile bypass contact 11a. A bypass circuit small in resistance value is therefore formed to the power source side of shorting fault point, so that the spreading of accident disaster is prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention can be inserted into the branch point of each customer in a low-voltage power distribution system, for example, and prevent current from flowing into a short-circuit failure part that occurs in the customer room. In addition to suppressing the spread of accidents and promoting the cutoff of short-circuit protection devices such as drop-in line fuses or high-voltage fuses, short-circuit accidents can be quickly removed from the power distribution system to prevent disasters. The present invention relates to a high-speed short circuit removal method that minimizes the occurrence of short circuits and prevents the development of widespread power outages.

(Prior art and its problems) When supplying electricity from the distribution system to consumers, generally the first
As shown in the figure, the voltage of the high voltage distribution line 0) is stepped down by the pole transformer (2) and led to the low voltage distribution line (3), and then the voltage of the drop line (
4), the electricity is supplied to the consumer (6) via the electricity meter (5).

By the way, in this case, in order to eliminate failures due to short-circuit accidents after the lead-in line (4), generally a lead-in fuse (7) is provided in series near the branch part (4a) of the lead-in line (4), as shown in Figure 1. This is the method that is often used.

However, the types of lead-in fuses used in low-voltage distribution lines are limited in terms of system operation; The short circuit current and the rated current of the fuse cannot be coordinated due to the fact that short circuit failures occur in a wide variety of situations, and in some cases it is only the high voltage side fuse. The operating time may be extended, leading to the spread of disasters and power outages. For example, a watt-hour meter is replaced with a certified one at regular intervals, but in this case, the service line is usually not equipped with a disconnect switch, so the watt-hour meter must be replaced while the line is still live. I don't get it. Therefore, for example, when an arc short circuit occurs due to an operator's error while attaching or removing electric wires during replacement work, the short circuit current is significantly limited by the arc voltage, resulting in a delay in the disconnection operation of the lead-in fuse. As a result, the arc heat may scorch the walls of homes or cause accidents in which workers may suffer burns.

(Objective of the Invention) The present invention proposes a method that can rapidly reduce the short-circuit current flowing at the fault point and speed up the breaking operation of the lead-in fuse using a small and inexpensive device, and prevent the spread of disasters at the short-circuit fault point as described above. This prevents the situation from developing into power outages or power outages.

(Means of the present invention for solving the problem) When a short circuit accident S occurs between the service line (4) after the branch point (4a) (hereinafter sometimes referred to as the load side) as shown in Figure 2. The short circuit current is not supplied from the utility room side which does not have a power source, but is supplied only from the low voltage distribution line (3) side (hereinafter sometimes referred to as the power source side). Therefore, immediately after a short circuit occurs, a forced short circuit occurs quickly on the consumer (6) side of the lead-in fuse (7), which is the power supply side where the short circuit occurred, and the impedance seen from the power supply becomes smaller than that at the time of the short circuit. By creating a bypass circuit B with a significantly smaller amount, it is possible to reduce the current flowing to the short-circuit fault point S, and prevent the arc mentioned above from burning the wall of the consumer by quickly extinguishing it. You can prevent it from happening.

Furthermore, the bypass circuit allows a larger current to flow through the lead-in fuse (7) than in the case of only a short-circuit failure. Therefore, the cut-off operation can be made quickly and reliably, and the customer (6) where the short-circuit failure has occurred can be quickly removed from the power distribution system, thereby preventing the risk of causing a power outage for other customers due to the continuation of the short-circuit failure. There are also few (can be done).

On the other hand, when a current of 1000 A or more is passed through two conductors, for example, 10 crn long, arranged in parallel with an interval, the interaction between this flowing current and the generated magnetic field (
Based on Fleming's left-hand rule), a sufficient driving force as shown in FIG. 3 acts on the conductor to move it.

Therefore, from the above, if a conductor is connected to both wires on the load side of the lead-in fuse of the above-mentioned lead-in line, when a current of several thousand amperes, which generally occurs due to a short circuit, flows, the distance between the conductors will be changed by the action of electromagnetic force. By providing a contact point on each conductor and closing it when an electromagnetic force is applied, the conductor itself can generate current without requiring a current detector or an operating power source. You can create a simple, small, and inexpensive bypass circuit that detects and works.

The present invention is based on the above-mentioned idea, and will be specifically explained below using embodiment figures.

(Embodiment) FIG. 4 is a diagram showing an embodiment of the present invention. In the figure, (1
1) is an immovable bypass conductor, (lla) is an immovable bypass contact provided facing upward near one end of the conductor, (llb
) is a lead-in line connection terminal, (11, c) is a lead-in fuse side connection terminal, (12) is a movable bypass conductor, and (12a) is a movable bypass contact, which is connected to the stationary bypass contact (l).
It has a folded part facing la) and is provided on the conductor (12). (12b) is a lead-in line connection terminal, and (12C) is a lead-in fuse side connection terminal.
), the end of the movable bypass conductor (12) is fixed to the shaft (12d) so that one end can move in the direction of the immovable bypass conductor (11), and the connecting terminal (12c) is fixed to the shaft so as not to impede the flow of current. ) and the movable bypass conductor (11) are connected, for example, by a flexible metal braid (12e). Also, the connecting terminal (12b) and the movable bypass conductor (1
2) The other end is a metal connecting body (12f), such as a flexible metal braid, so that the movable bypass conductor can move toward the stationary bypass conductor (11) and contact the contact (lla) (12a). Connected by the body. (13) is a fixed positioning insulator, which connects the immovable bypass conductor (11) and the movable bypass conductor (12) to the contact point (lla) and (12a).
) are fixed at a predetermined interval so that they are facing each other. (14)
is a movable positioning insulator and a stationary bypass conductor (1
1) is fixed, and the movable bypass conductor (12) is movably supported by the bearing hole (14a). (15) is a magnetic transmission body, (15a) is a split part for inserting a movable bypass conductor, and the movable bypass conductor (12) is a split part (15a).
) and are fixed to the positioning insulators (13) (14) so as to surround the stationary bypass conductor (11).

(16) is a case, and the above forms a bypass device B, which has connection terminals (llb) (llc), (
12b) (12c), both wires (4b) (4) of the load side lead-in wire of the lead-in fuse (7) are connected as shown in Figure 2.
c) connected in series.

(Function) When a short-circuit failure occurs on the utility room side of the high-speed bypass device B, a current (+■) flows through the immovable bypass conductor (11) in the direction of the arrow in FIG.
), current (-■) flows in the opposite direction.

For this reason, the area around the immovable bypass conductor (11) is as shown in Fig. 5 (
A magnetic field BA in the direction of the arrow in a) is generated, and a magnetic field Bl+ in the opposite direction to that of the stationary bypass conductor (11) is generated in the movable bypass conductor (12). However, the generated magnetic field BIl is blocked by the magnetic transmitter (15) and is almost entirely blocked by the stationary bypass conductor (11).
), and only the movable bypass conductor is located in the magnetic field between the opposing split ends of the magnetic transfer body (15) due to the generated magnetic field B, as shown in FIG. 5(b).

Therefore, a downward force F is applied to the movable bypass conductor (12) due to the current flowing therein and the magnetic field B, which causes it to separate from the immovable bypass conductor (11), and as a result, the movable bypass contact (12a) also moves downward. Fixed bypass contact (Ila)
). Therefore, since a bypass circuit B having an extremely small resistance value is formed on the power supply side at the point where the short circuit failure occurs, it is possible to prevent short circuit accidents from spreading.

The second example uses repulsive force, but for example, as shown in Figure 6, the movable bypass conductor (12) is folded back into a loop so that when a short circuit occurs, the immovable bypass conductor (11) and the movable bypass conductor By passing current in the same direction through (12), the movable bypass conductor (12) is connected to the immovable bypass conductor (
11) Generate an attractive electromagnetic force F in the direction and bring the contacts (Ila) and (12a) placed opposite each other into contact with each other to create a bypass circuit between the drop-in wires (4a) and (4b). You can also do that. Note that (16
) is a magnetic shield that covers the movable bypass conductor (12) other than the portion facing the immovable bypass conductor (11), and the magnetic field generated by this portion is transmitted to the movable bypass conductor (
12) does not affect the magnetic field in which it is located, thereby increasing the reliability of operation, and can be omitted together with the magnetic transmitting member (15) of Embodiment I.

In addition, in the above embodiment, one of the two bypass conductors was made movable, but by making both of the two bypass conductors movable, the time from when the short circuit fault current flows until the contacts make contact can be increased. Can be shortened.

In addition, although the present invention has been described above for a short-circuit failure on the load side of a lead-in fuse, by applying it to a high-voltage distribution system, it can be applied to a high-voltage distribution system, for example, when deterioration of the insulation part occurs, or when abnormal voltage due to lightning strikes etc. This can be effective in cases where an arc short circuit failure occurs. Furthermore, it can also be applied to general electrical wiring circuits.

(Effects of the Invention) As described in Section 2 below, the present invention detects a short-circuit fault by itself and shorts the circuit on the load side of the fuse, thereby rapidly reducing the current flowing to the short-circuit fault point and preventing the fuse from breaking. In addition, the device is small, simple, and inexpensive, and can be easily used on each service line.
In particular, it makes a significant contribution to the maintenance and management of power distribution lines.

[Brief explanation of the drawing]

Figure 1 is a power distribution system diagram. Fig. 4 is a diagram explaining the principle of . Example diagram and its action diagram, It is an example figure. Figures 2 and 3 show the invention Figure 5 shows one implementation of the present invention. FIG. 6 shows another embodiment of the present invention.

Claims (1)

[Claims] (1) In an electric circuit in which a load is connected to a power source via a short-circuit protection device, first and second contacts each having opposing contacts arranged in parallel on each of both wires near the load side of the short-circuit protection device;
Bypass conductors are connected in series, and the contact is closed by changing the distance between the first and second bypass conductors due to an electromagnetic force acting on the bypass conductor based on an excessive current that occurs when a short circuit occurs on the load side, This forcibly shorts the lines near the load side of the short-circuit protection device installation point, rapidly reducing the current at the point where the short-circuit accident occurs and increasing the current flowing through the short-circuit protection device, thereby preventing the spread of short-circuit accident disasters. A high-speed short-circuit removal method characterized in that the short-circuit protection device speeds up load shedding.