SU773788A1 - Fuse - Google Patents

Abstract

Electromagnetic arc extinction apparatus comprises an arc chamber 19 of insulating material and having an axial channel 22 and electrodes 20, 21 aligned with the axis of the arc chamber 19 and adapted to form a quenching arc 23 in the form of a helix. The cavity of the arc chamber is bent along a helix to cause the quenching arc 23 to be moved in a radial direction, the pitch of the cavity is at least 10 times lesser than the diameter of the arc chamber measured over the cross-section thereof. Conductor plates 16, 17 allow movement of arc roots. The apparatus of the invention is suitable for use on any desirable alternating- or direct-current circuits and can find use in high-voltage heavy-current switchgear including circuit breakers and fuses. <IMAGE>

Description

(54) FUSE FUSE

The invention relates to electrical engineering, and more specifically to fuses designed to protect electrical circuits from short-circuit currents, in particular, to protect high-voltage AC and DC circuits, power semiconductor equipment, etc.

Fuses are known in which | Q the growth (recovery) of the voltage on the quenching arc that occurs after the melting of the fusible element, and the shutdown of the protected network occurs by extending this arc jlj.

The disadvantage of this fuse is the large size, due to the large required arc quenching size and limited speed, determined by the time it takes to pull the arc to these dimensions.

The closest in technical essence is a fuse containing a fusible element and an arcing insert of insulating-25 material 2.

In this fuse, the electromagnetic force of the quenching arc generated after the melting of the fusible element causes the arc to bend, lengthen and fade, and the electrical breakdown between the elements of the curved arc limits the extent of the quenching arc compared to the length of the fusible element. This causes a relatively large fuse size and reduces its speed.

The purpose of the invention is to increase the speed and reduce the size of the electrical fuse.

To achieve this goal, the interrupter insert of insulating material is made in the form of a strip and is arranged in a helix around the fusible element.

In addition, the fuse can be equipped with a replaceable insulation rod, and a fusible element is wound on this rod with a step equal to the helix pitch of the arcing insert.

The drawing shows schematically the fuse, a general view.

Claims (2)

It contains a straight line: a fusible element 1, which passes along the axis of a screw arcing insert 2 of electrically insulating material, the arc 3 in the quenching position at some point in time after the fusible element melts. The fuse works as follows. The electric arc quenching formed after melting of the fusible element 1 departs from the axis of the interrupter insert 2 into the screw space between the turns of the insulating interrupter insert and takes on a screw shape. The interaction of current J of this spiral-shaped arc with the longitudinal component of the intrinsic magnetic field leads (as in a conventional solenoid) to the appearance of an electromagnetic field current ZxB directed radially from the axis of the insert. The motion of the quenching arc under the action of this force. In the screw cavity of the arcing device causes an increase in its length and the restoration of the voltage on the fuse. Another example of the proposed technical solution is the additional insertion into the insert of a replaceable insulating rod located along its axis. This stem is wound along a helix, for example flush, a fusible element with a pitch equal to the pitch of the screw insertion line. The position of the rod relative to the insert must be fixed to ensure that the fusible element is in relative position in the area between the insertion blades. Such a solution eliminates the possibility of electrical breakdown through the central hole of the screw inset and thereby increases its dielectric strength. in this fuse, the quenching arc length is Ig Ig 2l rLK / a, where L is the length of the screw insert of the arc-suppressing device, I is the step of the screw surface that is .. the insert,.: r (t) is the radius of the screw arc increasing as it stretches arc,) + R / iir -I - coefficient close to unity. The arc elongation rate is deg 2ftUKV / ft, where Vf, dr / dt is the speed of movement of the quenching arc column in the radial direction under the force of Ox Oh. From this it follows that the maximum voltage on the damping arc in the fuse with given dimensions (length L and the diameter D of the screw insert), is and, DLKE / I, and the voltage recovery rate is dU / dt in 2nd; gKug / I, where E is the electric field voltage in the arc column of the gas arc, estimated for values of arc current 3 200-2000 A; magnitude E: 30 V / cm. The presence of a screw insert will exclude the electric matic proboy.mezhdu vitkai helical arc quenching and allows ealizovat small values helical arc step. This ensures the compact placement of the quenching arc in the arc-shaped fuse device, and thereby reducing its dimensions. Indeed, the length of the screw arc in CO / I exceeds the length of the insert L times. Accordingly, in this fuse, the rate of arc extinction (and voltage recovery) is 21tr / jt times the speed of its radial movement, which ensures a corresponding increase in the speed of the fuse (without melting time of the fusible element). The arc is quenched when moving in the screw cavity of the insert weakly loads the material of the insert both thermally and mechanically. It should be noted that the material of the fusible element does not deposit on the screw surfaces of the insert, but is carried out in the radial direction. Therefore, the screw insert can be made, for example, from plastics by casting or stamping. To avoid gas escaping from the screw insert, when the safety device is triggered, an external cylindrical housing made of electrically insulating material can be used, which is worn on the insert. In this case, the inner surface of the casing, onto which the material of the fusible element is thrown, can be protected with a replaceable coating. Claim 1. Fuse comprising a fusible element and an arc absorbing insert of insulating material, characterized in that, in order to increase speed and reduce the dimensions, the interrupter insert of insulating material is made in the form of a strip and is arranged along a helix around the fusible element. 2. The safety device according to clause 1, which is distinguished by the fact that it is equipped with a replaceable insulating rod, and a fusible element is wound on this rod with a step equal to the pitch of the helix of the arcing insert. Sources of information taken into account in the examination 1. V. V. Alekseev. High-voltage and low-voltage fuses. Moscow, Publishing House of the Ministry of Municipal: households, 1961. 2. USSR author's certificate number 196982, cl. H 01 H 85/38 ,. 1967.