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The high-voltage dropout fuse collection short circuit protection, the overload and isolating circuit's function is a body, widely usesd on the distribution line and the equipment, it can use in  small power and to be protective value request not high place, it also may use with the isolator coordination, replace the automatic air switch; With the load switch coordination use, replaces the  high price circuit breaker. The fuse's structure is more simple and protects reliably, but if uses improper, will cause to move by mistake or not to act, creates the inevitable economic loss. Therefore, it is the necessary to understanding and use fuse.

1.The work process, the melt chooses and installs the request

1.1  Process

When fuse movement connects in the power circuit, In normal work, it contact with fuse button's install in the cartridge fuse, is loaded with the sheeting depressurization's hat to contract, the fuse buttcock line pulls out through the cartridge fuse, will spring board to turn back pressure near nozzle, with under contact connection, in springs board torsion under the function the fuse to be at the tautness condition, and locks the active joint. When the fuse occupies switches on the position, because on static contact downward and shrapnel outward thrust, causes the whole fuse's contact to be more reliable.

When the electrical power system breaks down, the fault current blows the fuse rapidly the fuse, produces the electric arc in the fusion tube, the cartridge fuse produces the massive gas under the electric arc function, when the gas surpasses the value of pressure which assigns, released the sheeting namely the discount to open along with Niu, reduced in the cartridge fuse pressure, has had the intense ionization in the electric current zero hour, caused the electric arc extinguishment. But when the gas has not surpassed time the value of pressure which assigns, releases the sheeting not to act, the electric current zero hour has produced the intense free gas from under nozzle blowout, springs the board to pull out rapidly the fuse buttcock line, causes the electric arc extinguishment. After fuse's fuse moves the joint release, the cartridge fuse under on static contact under the shrapnel pressure, in addition is in itself self-possessed the function rapid depreciation, shuts off the electric circuit, forms the obvious breaking gap.

1.2 Melt choice

About how to choose the size of fuse (piece)'s question, first acts according to the different protection object, chooses the corresponding model and the corresponding time - electric current characteristic fuse, but must consider factors and so on upper and lower layer coordination, accurate choice concrete parameter. 

1.3 Installs the request

The dropout fuse, its fusion tube spool thread should become with the lead perpendicular line 15~30°, its component moved nimble , when droped should not bump and other objects;

The fuse's specification should tally with the design requirements, should non-bend compressing or the damage, the melt should press closely with the contact reliable

1. Fuse's install need to be vertical, prevents the electric arc to fly falls on the near equipments' part;
   
2. Fuses and the fixed contact should be straight line, the non-sloping contact;
   
3. Fuses must mark the fuse and the melt (silk or piece) the nominal current, the melt's capacity should tally with the electric appliance's request, not or not nominal current indication's melt does not permit to use after the verification.

The high-voltage dropout fuse uses the insulating stud single-phase operation, don't permit of the belt load operation. Through the practice we discovery that, when the belt load pulls open by wronged operation, the majority situations with separate the parallel return route or the ring circuit are similar, the release voltage is low, won't causes intense electric arc. But when the belt load pulls open second, because the fracture voltage is a line voltage, its fracture voltage is high, will therefore have the intense electric arc, possibly will cause each to have the arc light neighboring to short-circuit, will threaten the person and equipment's safety. But when pulls open the third-phase, because the electric circuit already tends the opening (does not have electric current or electric current is very small), will not produce the electric arc. Therefore grasps the correct, the standard operation sequence and the method guarantees is the safe key.

Although at present "Electric power Trouble-free service Regulations" have not made the stipulation to the high-voltage dropout fuse's operation, but in practice  we discovery that, regarding to the level and time triangle arrangement high-voltage dropout fuse operation should achieve the following several spots.

1.Before completing the operation we should do preparatory work, selects the corresponding voltage class and the qualified insulation tension bar, wears the insulating gloves, puts on the insulation shoes, completes the preparatory work fully.

2.Before the operation, must check the equipment's name and the serial number earnestly, to determination the operation's accuracy.

3.To choice the advantageous' operation position to stand, generally stand before current operation dropout fuse's underneath for suitable. If is on the poles and towers operation, but should also wear the safety belt on.

4.When operation the high-voltage dropout fuse, moving contact to aim at its static contact, guaranteed the accuracy of gathers the position.

5.When gathers the high-voltage dropout fuse, we must rapid, decisive, accurate, but when near the bottos gather, cannot make an effort excessively fiercely, for will damage insulator support and other equipment.

Moreover, we should also pay attention to the actual operation:

operation sequence: When gathers the fuse, gathers nearby first, and the intermediate phase later, it's opposite when separation, has the wind gathers fuse

The high-pressured depreciation type fuse also has the fuse electric current characteristic in the daily movement not to be unstable, along with the movement's environment, the temperature change, causes the coordinate fault and trip phenomena and so on, to jump the ranks; if the fuse tube quality is bad, the distortion aliquation can cause to drop by mistake; if uses for a long time ,it easy to cause high and low contact bad contact, the contact to give off heat, situations and so on loss by burning and contact oxidation; Because in running the operates, the use, to install improper causes the performance to suffer injury. Therefore, the correct standard's and the enhancement technique of production level, develops the high quality's high-voltage dropout fuse, is guarantees the electrical power system safe reliability service the important task.

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