Test and identification of authoritative institutions, such as insurance companies ICE certification experimental American UL certification, the Canadian Standards Association CSA certification, the Ministry of international trade and industry of Japan MTTI certification and international electric technical committee. The following conclusions are obtained:
The selection of the fuse relates to the following factors:
1 normal operating current.
2 applied voltage on the fuse.
3 requires that the fuse is disconnected from the abnormal current.
4 the shortest and longest time allowed to exist.
5 ambient temperature of fuse.
6 pulse, impulse current, surge current, starting current and circuit transient value.
7 whether there are special requirements beyond the specification of the fuse.
8 mounting structure size limits.
9 requirements of the certification body.
10 fuse holder: fuse clip, mounting box, panel mounting, etc..

Here are some of the common parameters and terminology used in fuse selection:
Normal operating current: operating at 25 C, the current rating of the fuse is typically reduced by 25% in order to avoid harmful fuse links. Most conventional fuses have a lower melting temperature for the materials used. Therefore, the fuse is sensitive to changes in ambient temperature.
For example a fuse with a current rating of 10A is typically not running at a current of more than 7.5A at ambient temperature of 25 c..
Voltage rating: the voltage rating of the fuse must be equal to or greater than the effective voltage of the circuit. General standard voltage rating series for 32V, 125V, 250V, 600V.
Fuse is a voltage difference, such as in the case of rated current under the same fuse and fuse 220V 10kV difference is very big, although the same current can make the fuse, but if the voltage is too high, the fuse will not be able to guarantee the insulation safety of fracture.
So the high-voltage fuse can be used in low pressure, but the low pressure can not be used in high pressure.
Resistance: the resistance of the fuse is not very important in the whole circuit. But for a fuse with a fuse of less than 1 a few ohm, the problem should be considered when using a fuse in a low voltage circuit. Most of the fuse is made of a material with a positive temperature coefficient, so it is also divided between the cold resistance and the thermal resistance.
Ambient temperature: the current carrying capacity of the fuse, the experiment is carried out under the environment temperature of 25 degrees Celsius, this experiment is affected by the environmental temperature change. The higher the ambient temperature, the higher the working temperature of the fuse, the lower the current carrying capacity of the fuse, the shorter the life expectancy. On the contrary, the fuse will be extended at a lower temperature.
Fuse Rated Capacity: also known as breaking capacity. Fuse rated capacity is the maximum allowable current that fuses can fuse at rated voltage. When a short circuit, the fuse will be through a large number of normal operating current large transient current overload. Safe operation requires the fuse to remain in full state (no burst or break).
Fuse performance: the performance of the fuse is the fuse of the various current load to make the rapid response. The fuse is normally divided into four types: normal response, time delay, fast action and current limit.
Harmful open circuit: often due to the design of the circuit analysis is not complete. All of the factors involved in the selection of fuses listed above must pay special attention to the normal operating current, ambient temperature and overload. In use, can not only according to the normal operating current and ambient temperature to select the fuse, but also pay attention to other conditions of use. For example, one of the common causes of hazardous open circuit breakers is that the nominal value of the fuse is not fully considered, and it must also be satisfied.
2 surge current generated by the power supply smoothing filter of the input capacitor to fuse the requirements. If the fuse is safe and reliable to work, then to use the fuse of melting heat energy is not more than 20% of the nominal value of the fuse.
Thermal energy: refers to the energy required to fuse the fuse unit, using I2t, read as "ampere square seconds". In general, certification authority, to test: melting heat energy by applying a current increment and the measurement of melting occurred time to fuse, if the melting does not occur in about 0.008 seconds or longer, then increase the intensity of pulse current.
Repeat the experiment until the fuse time is less than 0.008 seconds. The purpose of this test is to ensure that the heat generated is not enough time to run away from the fuse component through the heat conduction, that is, all the heat energy used to fuse the fuse. Therefore, when the fuse is used, in addition to the normal operating current, to reduce the rated value, the ambient temperature, but also consider the I2t value.
Also note: since most of the fuses have welded joints, be particularly careful when they are welded. Because soldering heat is too much will cause the solder reflow in the fuse to change its rating. The fuse is similar to a semiconductor thermal element, so the heat absorbing device is preferably used in the welding fuse.