The choice of fast fuse reachs application

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Rectification changes report is the important segment in chloric alkaline industry, and fast fuse changes in commutate of semiconductor electric power the configuration in electric protection is crucial, once equipment finalizes the design hind, the commutate such as the chooses power supply of dc of can immediate impact quality of fast fuse and the efficiency that use phone changes electric parameter. Thermal capacity of electric power semiconductor device is small, must want to have fast fuse protection below state of fault, and fast fuse has as similar as semiconductor device hot character, it is a kind of good protection parts of an apparatus. What the article involves is enclosed have packing type fast fuse, exterior phenomenon is done not have in move. The in configuring fast fuse to be protected in commutator of semiconductor electric power configuration of 1 fast fuse divides 2 kinds commonly. 1.

1 change this type basically uses formula of protection of configuration of spur track of paralell connection of interior drifting an arm at high-power and the protection that exceed high-power commutator. Should change when parts of an apparatus of spur track of the some in spreading an arm damages because of some kind of reason (each spur track differs according to equipment power, a few pairs of fast fuse mix general paralell connection to semiconductor commutate component establishs ties and be become, graph 1 only line out 1 pair of fast fuse and semiconductor commutate component) , after bringing about the fast fuse that establishs ties to it to protect disjunction, usually only a parts of an apparatus gives trouble, what do not affect whole commutator is normal move. Current, the protection of commutator of semiconductor electric power of limited company of chemical industry of Ji Dong of 3 friendly groups configures Tang Shan mediumly to be belonged to change configuration of spur track of paralell connection of interior drifting an arm protects type, moving effect is very good, if pursue,1 is shown. 1.

2 split phase configure the protection that this type basically uses overall protection formula at commutator of medium, small-power. Change when some when the parts of an apparatus in spreading an arm damages because of some kind of reason, after bringing about this fast fuse to protect disjunction, the protection of rectifier will cut off power supply source automatically, stop to rectifier power supply, chloric alkaline industry often is not configured with this, if pursue,2 are shown. Of 2 fast fuse choose also call voltage electric current the law. The line voltage of circuit converter transformer should the rated voltage under fast fuse. Via test and verify of electric power semiconductor device and experiment of short circuit of fast fuse series connection, with semiconductor rated electric current is multiplied with coefficient, as the rated electric current of chooses fast fuse. Because the rated electric current of fast fuse is virtual value, and the rated electric current of semiconductor device is average, be aimed at plan of afore-mentioned the first kind of configuration (graph 1) , to series of RS0 of generation product, RS3 (the phylogeny of our country fast fuse can be divided for 4 phase, generation is series of the RS0 that the whole nation designs jointly, RS3, parameter is 480A, 750V the following, disjunction ability is 50kA, it is a kind of bulk bigger, price the raw product with brief life of cheap, report, at present Shang Youxiang is become installation amount) , this coefficient can is by rectification canal 1.

4, transistor 1.

2, fast transistor is 1 will choose match, if ZP1000 matchs 1400A fast fuse. Be aimed at plan of afore-mentioned the 2nd kind of configuration (graph 2) , can choose fast fuse according to the load performance of Iv of electric current of a powerful person and deflector, the biggest fault current that generates possibly by rectifier again, will choose to have the fast fuse of enough disjunction ability, be like 50kA or 100kA, among them 50kA is tasted for qualification, 100kA is tasted for one class. The applied character   of 3 fast fuse 3.

Carrying capacity of 1 electric current is fast the rated electric current of fuse is with virtual value denotive, the 30% ~ that are nominal and rated electric current through electric current normally commonly 70% . When fast fuse is used or one of end are heated by semiconductor device and another end is discharged to cool by water-cooling mother, or double-faced be discharged to cool by water-cooling mother; Or have compulsive wind cold will control what temperature rise makes to maintain voltaic carrying capacity. The temperature rise that the join situation that fast fuse connect handles in rectifier is affecting fast fuse directly and move reliably, it is this to must maintain the level off of interface and cleanness. If do not have the mother of film,the interface of the platoon wants purify oxidation layer, formulary thrust gives when installation, had better make interface produces flexibility to be out of shape. One by one of shunt-wound fast fuse requirement detects of interface pressure fall. 3.

The temperature rise of 2 fast fuse and power comsumption are fast the UIw of Δ of power comsumption W= of fuse; In Δ U=f(Iw) type: Iw---Working electric current; Δ U---Of fast fuse pressure fall. The power comsumption of fast fuse and resistor of its cold conditions have very big concern, choose the fast fuse with cold conditions lesser resistor to be helpful for reducing temperature rise, because voltaic carrying capacity basically gets temperature rise,restrict. The place before be like is narrated, the join situation that fast fuse connect handles also is affecting the temperature rise of fast fuse, the temperature rise that asks fast fuse connect is in should not affect the work of parts of an apparatus of its photograph adjacent. The experiment proves, the temperature rise of fast fuse under 80 ℃ when can move for a long time, the product with the stable workmanship when 100 ℃ still can run temperature rise for a long time, temperature rise the critical point that 120 ℃ are voltaic carrying capacity, when be like temperature rise to achieve 140 ℃ , fast fuse cannot move for a long time. Current, chemical industry uses water-cooling mother to discharge zephyr cold pattern to reduce the temperature rise of fast fuse commonly. Water-cooling mother platoon is like effect of 400 ~ 600V to the fast fuse of low voltage norms especially much better. Fast fuse terminal and join of water-cooling mother platoon carry difference in temperature to be in commonly 1.

0 ~ 2.

0 ℃ . A lot of high-power are fast fuse is designed by water-cooling condition, so, ask should hang down to the manufactory before the user is being used. Wind is cold also be a kind of effective method that reduces temperature rise, will decide wind speed is right according to curve of wind speed carrying capacity the influence of fast fuse temperature rise, when wind speed makes an appointment with 5m/s, can rise commonly of 25% shed ability, if wind speed increases again will not have apparent effect. According to the power comsumption below the curve of fast fuse voltage drop that the manufactory offers and rated electric current, measure fast fuse the voltage drop between polar terminal can be calculated quickly the practical electric current that gives this spur track. Additional, connecting likewise shed a circumstance, whether is temperature rise still used with fast fuse onefold or double concern. What fast fuse uses more in the high-power commutate device that advanced industry country makes is double establish ties with semiconductor device, be like 700A × 2, 1400A × 2, 2500A × 2. Double and fast fuse terminal of the structure can be decreased as far as possible thin, in order to reduce resistance. Have a kind double and fast fuse relies on connective bolt and even board join, another kind is to connect board (terminal) with 2 fuse-element (terminal) the structure that solder is an organic whole, this kind of structure is more advanced. The fast fuse with taller voltage its internal resistance is greater, especially 800V above product, because crust porcelain covers the length with have certain, exterior accumulating is bigger, and the filling of by of quantity of heat that fuse-element produces, crust is conducted medicinal powder hot, the fast fuse with reason tall voltage wind cold effect is more distinct. 3.

The chooses fast fuse crust intensity of 3 disjunction ability decided the disjunction capacity to the biggest fault current greatly. Next, the metallic frit of fast fuse interior piece of ability of vapour of metal of adsorption of appearance, filling and quantity of heat, fuse-link electrodynamic wait to affect disjunction ability. When designing rectifier, should calculate " rectification transformer " alternate with short-circuit current, choose the fast fuse that has enough disjunction capacity by this electric current. Till explode,the fast fuse with disjunction insufficient capacity can light arc continuously, serious when can bring about make dc short circuit, reason is rated disjunction ability is a safe index. Additional, the dispersive sex that the product makes also is one of factors that affect disjunction ability. The issue that ignores easily is the power factor in the circuitry when short circuit breakdown, because be when fast fuse disjunction,the size of the size of the electric arc energy that produces and circuit inductance has very big concern, when < of φ of Cos of circuit power factor 0.

2 when have particularly high demand to disjunction ability. In the type of energy Wo=Wa+Wr+W1   when fast fuse disjunction: Wa---Electric arc energy; Wr---Resistor wastes energy; W1---The energy that circuit inductance releases. Satisfy in disjunction ability " rectifier " when the requirement, notice peak value of voltage of disjunction instant electric arc even (call in the standard " transient restores voltage " ) cannot exorbitant, should give when fast fuse is made limitation, make its under semiconductor device can susceptive maximum, otherwise semiconductor device will damage. The fuse with reason disjunction the shortest time is not certain the most applicable. When fast fuse is used in dc road, because of nonexistent in dc disjunction process voltage over- at 0 o'clock, this is a slashing condition to the reliable disjunction of fast fuse, usually so fast fuse is like fast fuse can be used only in be being used in dc road 60% of rated voltage, had better choose dc fast fuse. 3.

4The size of the chooses fuse fusing time T of I2t and I of fusing electric current is concerned, its rule is the square with electric current becomes inverse ratio. Graph the 3 relation curves that express T ∞ 1/I2, the second that calls fuse - install characteristic curve. As a result of all sorts of wiring (include electrified wire netting) have certain overload capacity, should can allow to move more for long when overload is lighter, and when exceeding some overload multiple, corresponding requirement fuse is inside proper time fusing. Choice fuse protects overload and short circuit, the overload that must know the equipment that use phone is characteristic, make this one character lies appropriately fuse second - in the protective range that brings character. By the graph 3 visible, the fusing time of Io of fusing electric current is right talk going up is infinity, call the smallest melt electric current or critical electric current, the electricity that carries fuse-element namely is less than critical value won't fusing. The Ie of rated electric current that chooses fuse-element so should be less than Io; The specific value that takes Io and Ie normally is 1.

5 ~ 2.

0, call fused coefficient. The different protection of fuse of this coefficient report when overload is characteristic, if want to make fuse can protect small overload electric current, melt coefficient should some lower; When starting to avoid electromotor short when cross electric current to make fuse-element fused, melt coefficient answer some taller. Fast frit implement after voltaic carrying capacity satisfies the requirement of systematic short-circuit current, short-circuit fault current can be kept apart when breakdown, but whether the I2t value that protects the semiconductor device of a series connection to must analyse both. When only the I2t value when fast fuse is less than semiconductor device I2t to be worth, ability protects action to arriving since semiconductor device. The I2t when short circuit breakdown is worth cent to be two phase, namely the I2t before arc and fusing I2t. Fuse-element metal turns from solid state the time that is liquid state is the time before arc, about 1.

0 ~ 2.

0ms, can consider as adiabatic process, this time paragraph the voltaic time integral that fast fuse produces can consider as fair value, will decide by the design. The I2t before arc is worth to different material its value also differs, to material of avery kind of it is a constant. Turn into when fuse-element metal the electric arc when steam only then light, in process burning arc electric current falls by current limliting value to 0, the I2t of this phase is fusing I2t namely, it is a variable. This one process basically relies on filling to be corroded and draw energy. When designing fast fuse, to satisfy the rated electric current that semiconductor device increases ceaselessly, want to take a lot of step, and cannot choose fast fuse simply with arithmetical method. The experiment proves, increase when rated electric current 1 times when, the I2t value of fast fuse is 4 times original, and the addition that semiconductor device I2t is worth wants many small. Want to make fast fuse reduces I2t value to have greater difficulty, only many sided takes step, like reasonable frit piece distributing, shorten fuse-element length, reduce electric arc bar and rise destroy the extinguish arc ability of arc material. I2t is worth one of main index that are handpick and fast fuse. 3.

5 insulation resistance are sudden it is very important that the index of the insulation resistance after fuse disjunction is proved by experience. 20 centuries joined salt of sylvite, natrium in the product with 90 many time, sodium salt can increase the disjunction capacity of electric arc bar. And the insulation resistance after making poorer fast fuse disjunction mostly under 0.

3M Ω , have appearance of leakage of electricity even, the classics after breakdown is being cut off below special situation is lighted again again for some time, this will cause bigger trouble. The fast fuse with good quality (joined salt of sylvite, natrium) should form after disjunction 0.

The insulation resistance of 5M Ω above. Fast fuse can achieve the insulation resistance that is more than Ω of 1 ~ 30M after disjunction 10min, can think to have good reliability. Additional, its life and dependability consider even when using fast fuse; The insulation resistance index after disjunction (> 0.

5M Ω ) ; As far as possible low transient restores voltage; Do not use have invisible the product of breakdown. CNC Milling CNC Machining