高压限流熔断器通常被人们认为是一种结构简单，保护可靠，投资较省的一种保护电器。实质上，这种熔断器虽然结构简单，但必须以严格的工艺和质量控制规范保证方能生产出可靠的高性能产品,同时还要正确的使用否则有可能导致它的保护功能丧失。以下简要介绍该产品的选用导则，欲了解详情请与本公司联系.
The high-Volt limit-current fuse generally is known as one protection electrical device with characteristics of simple structure,reliable protection and economical investment，however，actually though this type fuse has simple structure，this product with super performance only can be manufactured by means of strict technology and quality control norm, additionally,it is only
correctly using-it that can make full use of its normal protection function. this product’s use regulation would be introduced briefly below, anyone needing to have more information about it please contacts us．

对于熔断器来讲，使用时的安装环境条件很重要，它不但影响熔断器·性能，而且影响其可靠分断故障能力。因此根据使用条件要
加以正确的考虑.常见的一种安装方式是把熔断器安装在一个三相封闭的箱体中，这时熔断器须降容1 5％使用。额定电流小于20A的熔断器可不
考虑降容，因为小额定电流熔断器发热少，温度低，封闭环境对其影响不大。还有一种安装方式是把熔断器单支封闭在一个绝缘树脂浇注的筒内，在这种情况下，熔断器须容2 5％使用才能保证不使熔断器过热而损坏。额定电流2 0 A以下的熔断器仍可不考虑降容。按照有关标准规定，熔断器正常工作的环境温度在-2 5℃—+4 0℃之间，当温度低于-2 5℃时熔断器的机械性能将受到影响，而当温度高于+4 0℃时每升高1℃熔断器应降容1％使用。
对并联熔断器截流特性和I2t特性可遵循下式原则
lp总=n x(单—熔断器预期电流lp／n时的l p1)
式中lp总—并联后的截流峰值；
n—熔断器并联数：
lp—预期电流有效值；
Ip1—单—熔断器截流峰值
I2t总=n x(单—熔断器预期电流lP／n时的I2t值)
需要注意是决不能把熔断器简单的串联使用在高一级的电压电路中

The instalIment surrounding condition in use is very important for the fuse in that it not only affects the fuse’s perfo rmance,but also takes infuence on the reIiabIe abiIity of b reaking obstacle,therefore,operator should take the use condition into account．One common instalIment way is instalIing the fuse into case body with three-phase being sealed,at this time,thefuse should be decreased by 15 percent in capacity before used except the fuse with rated current being lower than 20A,because the fuse with smalI rated-current has Iittle heat radiated in addition to Iow-temperature,so the sealed surrounding does Iittle influence onto it．Another instalIment way is sealing one set of fuse into one tube poured with insuIation resin,under this circumstance, the fuse should be decreased by 25％in capacity before used in order to prevent the fuse from being damaged because of over-heated except for the fuse with rated current being Iower than 20 A According to relevant standard regulation,the normol work the fuse temperature of fuse ranges from-250℃ to 400℃,The fuse’s mechanical performabce would be affected positively provided the temperature is Iower than-25℃,vice versa,the fuse should be reduced by 1％in capacity per 1 Rise in temperature when the temperature is upper than 40℃before used.

As for the fuse installed in the cupboard with th ree-phase being not sealed,for the mutual interruption between temperature-
rising of th ree-phasefuse,the fuse could be decreased by 1 0％in capacity before used except for fuse with rated current being
lower than 20A．Generally, as for the fuse with rated current being lower than 10A，operator should do his best to make the fuse
away from landing metal support because of fuse-body’s easily-aging resulted from long-term co rona discharging . For
strengthening the current grade of fuse sometime，user would use two or three untis of fuse device for paralleling use,at this
time,the mutual influence between fuse’t emperature should be taken into account by operator,and the fuse should be decreased
by 10-20％in capacity for use generally.
The stem-current and 1²t properties of paralleling fuses can conform to following principle Ip-total：n x(the lp1 of single-fuse’
anticipated current beingl_p/n)
In the equation：Ip-total the stem-current climax value after paralleling n the fuse\s parallel quantity
1_p valid value of anticipated current
1_p1 stem-current climax value of single-fuse
l²t total：n x(the l²t value of single-fuse,anticipated current beingl_p/n)
Noted：the fuse’simple series-connection is banned from being used in the one-grade higher volt circuit

在安装前首先注意熔断器是否完整良好，清洁。如果受过摔落或剧烈振动则应检查其电阻值及仔细查看瓷管表面是否有裂纹。
在安装时，需注意熔断器上所标的撞击器方向，正确安装后，锁紧底座上的钢卡(或紧固螺栓)，防止过松接触。
在三相系统中，当只有一支熔断器发生动作后，一般熔断器均应更换，除非能证实仅有一支熔断器通过故障电流，因为尽管其它两支未动作，但有可能严重损伤或接近损坏。
在更换熔断器时需非常小心，因限流熔断器在运行时有一可靠的动作范围，但不能保证每一故障条件均在其可靠范围内，如开关装置脱扣失灵，或熔断器在低于其最小分断电流下动作等。为了安全起见，至少要等待熔断器动作10分钟以后且电路被其它电器隔离情节的情况下才能更换，一定要保证熔断器在不带电条件下更换。
在一般的电力系统中，如果选择适当，熔断器应很少发生动作。如果不是这种情况，则很可能是系统选择配合不当或计算选择有误以及线路连接有问题等，应进一步检查和计算。
对于正常运行的熔断器，定期检修设备时，可用测量熔断器内阻的变化来判断是否老化， 内阻的变化范围应在±10％之内。

Before installment, operator should check out whether the fuse is complete／good／clean or not,provided the fuse has suffered
from being fallen and violent vibration, operator is supposed to examine its resistance value and whether the porcelain tube has
crack or not on surface.
During installment，operator should take notice of the collision device’s direction marked on the fuse, after the install ment is
finished, operator should lock steel-fastener(or fastened bolt)on bottom base tightly to prevent from loosely contact.
In the th ree-phase system, the common fuse device should be changed after one unit fuse happen motion except for that
operator could ascertain that only one fuse device is electrified with obstacle current，because although another two hasn’t
happened motion, there maybe exist serious impairment on them.
Ope rator should be very careful at the time of changing fuse device, for the limit-current fuse has one reliable motion scope during operation，but it can’t be guaranteed that every obstacle condition is within its reliable scope(such as some wrong with the switch appliance trip, or fuse conducts motion in case of being lower than its minimum brokencurrent)．consequently,for the sake of security，operator couldn’t conduct changing until the fuse’s motion has last fo r 10minutes or longer and the ci rcuit has been isolated from other electric devices, in a word．the fuse should be changed under the circumstance of being without any electricity.

In the common electrical system，the fuse should conduct motion in low frequency if it is selected suitably,Besides this case above,it is far more likely that it has some wrong with system selection compatible problem，calculation selection or wire connection．So if the frequency is high，operator is supposed to check out and compute further
As for the fuse of normal operation，during examining and repairing equipment, operator could check out whether the appliailce is aging or not by means of measu ring fuse’s internal resistance，and the fluctuation scope of internal resistance should be within±10％.

用于直接起动的熔断器额定电流的选用按如下公式：
l_y=δ NIn
式中： δ—综合系数(见表)；
N—起动电流与电动机满载电流之比，
通常取N=6：
I_n—电动机满载电流：
l_y—在起动时间内的电流值。
在时间-电流特性曲线上找到起动时间对应的ly值点，点所对应的曲线或靠近的这一点右边的曲线即是选用的熔断器．熔断器
额定电流应大于1．3倍电动机的满载电流。

The rated current selection of fuse for directl starting should confo rm to following equation：
1_y=δ N1n
In the equation：δ comprehensive coefficient(refer to form)
N—the ratio of start current and motor’s fuIly-loaded current
General ly，N-equals 6
1_n—motor‘s fuIly-loaded current
1_y—the current value in the start-time
Finding the ly value-point corresponding with start-time on time-current characte ristic curve，the curve corresponding with point or on right side of point is the selected fuse，the fuse’s rated current should be bigger than 1.3 times of fully-Ioadedcurrent of motor