Selection Method Of Fuse

Selection Method Of Fuse

1.Normal Current: First we must know the normal current size that flows through the fuse in the circuit used. 

Usually we have to set a reduction in advance, and then choose according to the following principle: that is, the normal current must be less than the product of the rated current and the reduction coefficient. 

2.Fuse Current: In accordance with UL specifications, the fuse should be quickly fused at a rated current of twice times. In most cases, however, in order to ensure a reliable fuse, we recommend that the fuse current should be greater than 2.5 times times the rated current.

In addition, the fuse time is important, but also must refer to the fuse characteristic diagram provided by the manufacturer to make a judgment. 

3.Open Circuit Voltage: open circuit voltage should generally be selected to be less than the rated voltage.

For example, when a fuse with a rated voltage of dc24v is used in a ac100v circuit, it is possible to ignite or break the fuse. 

4.Short-circuit current: The maximum current value we flow when the circuit is short-circuited is called short-circuit current. For various fuses, the rated break capacity is specified, and we must be careful not to make the short-circuit current exceed the rated circuit capacity when selecting the fuse.

If a fuse with a small broken circuit capacity is selected, it may break the fuse or cause a fire. 

5.Impact Current: The waveform (pulse current waveform) for the observation of the impact current is used to calculate its energy using the I2T value (Joule integral value). The impact current is different in size and frequency, and the effect on the fuse is different. The ratio of the i2t value of the impact current to the fuse i2t value of a single pulse determines the number of times the fuse is resistant to impact current.