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Arc Extinguishing Method Of Low-voltage Switchgear
Oct 11, 2017

Arc extinguishing method of Low-voltage switchgear

One of the methods of Arc quenching: elongate arc

The arc is elongated, the electric field strength is reduced, Low voltage Switch or the arc is divided into many short arcs, so that the electric field strength cannot sustain the arc.

The bridge-type contact of the AC contactor, the lower part is the fixed contact head, the upper is the movable contact head, and the current flowing through the contact is I. When the contact is turned on, an arc appears between the static and the contact heads. We use the right-hand spiral rule to determine the direction of the magnetic field from the outside into the paper, and then use the left-hand rule to determine the current I on the arc generated by the electromagnetic force F direction outward.

The arc is elongated and cooled under the action of Force F, and the electric field strength of the internal unit length of the arc is reduced, Low voltage Switch and the arc is extinguished.

Arc Quenching method: Cooling medium to cool the arc

The arc-extinguishing sand in the molten core of the low voltage fuse uses fine sand to cool the arc until it is extinguished.

Three methods of Arc extinguishing: arc-quenching is used to extinguish arc

The electromagnetic force is used to make the arc enter the arc-quenching narrow seam made of insulating material, so that the arc is forced to cool down, the ionic motion speed is reduced and the ion recombination in plasma is accelerated.

The arc-extinguishing gate is a series of $number 5mm steel plates, which are placed in the interrupter of Low-voltage switchgear and are insulated from each other.

The original arc is produced when the moving and static contacts are separated. Because the magnetic resistance of the arc gate is much smaller than the air, the magnetic flux density of the lower arc is far greater than that of the magnetic flux density at the upper part of the arc, which pulls the arc into the arc-extinguishing gate, and the arc is divided into many short arc segments connected with each other. Low voltage Switch Although each of the two arc-extinguishing gratings can be regarded as a pair of electrodes, because the arc gate electrode is mutually insulated, so the insulation is very strong, so that these short arc sections under the Arc-extinguishing grid insulation and cooling effect of forced cooling off.

The arc-extinguishing gate can not only cool the arc cooling, but also produce a "cathode effect" effect on the arc.

We know that air molecules are ionized to form positive cations and negatively charged electrons, and the mass of positive ions is much greater than that of electrons. We also know that alternating currents are two times a week over 0. When the arc enters the arc gate, because the cathode and anode polarity of the contact is changed after the current is over 0, the direction of the positive and negative ions should be changed. Electrons in the vicinity of the original anode can easily change the movement direction toward the new anode because of the small mass, but the positive ions because of mass but not easy to change the direction of movement, Low voltage Switch they almost all stay in the original position, so near the new cathode due to lack of electrons in the flow, and then the arc is accelerated out.

Arc Extinguishing method: Seal the arc in a high-pressure vessel or vacuum container

The tubular fuse and vacuum circuit breaker take this method to extinguish the arc.