In the choice of fuse is that we are very headache, this is because there is no a good guide, the following China fuse block factory will fuse selection involved in the factors listed, you can choose the most suitable fuse according to these ideas.
1. Normal working current: at 25C, the reliable working current of the fuse is usually 75% of the rated current to avoid failure.Example: in a 25C environment, it is generally not recommended to use a fuse rated at 10 amperes operating above 7.5 amperes.
2，Application voltage (ac or dc) : the rated fuse voltage must be equal to or greater than the voltage of the application circuit.
3, ambient temperature: the higher the ambient temperature, the hotter the fuse work, the shorter the life.Conversely, working at lower temperatures will extend the life of the fuse.The fuse will also be hotter when the normal working current is near or over its rated value.
4. Overload current: it defines the current that the circuit needs to be protected in the case of failure.The fault condition can be current, or current and the maximum fault time that can be sustained before damage occurs.In matching fuses and circuits, time-current curves should be considered, however, keep in mind that the curves are based on average data.
5. Maximum fault current: the fusing current rating of the fuse must reach or exceed the maximum fault current of the circuit.
6，Pulse (current jump, surge current, start current and circuit transient) : electrical pulse conditions may vary greatly from application to application.Different fuse configurations may not respond equally to a given pulse condition.Thermal cycling and possible mechanical fatigue caused by electrical pulses can affect the life of the fuse.Initial or start pulses are normal for some applications where fuses are selected to include a thermal delay design to maintain normal start pulses and still provide protection against prolonged overloads.In selecting a fuse that corresponds to the start pulse, we should refer to and compare the fuse’s time-current curve and I2t rating.
7. Physical size limitation: please refer to the manufacturer’s data sheet for information on fuse length, diameter and height.
8. Institutional approval required: refer to the manufacturer’s data sheet for institutional approval information on specific equipment, such as UL, CS, VDE, METI or MITI.Military requirements require special consideration.
9. Fuse features: please refer to the manufacturer’s data manual for installation type/dimensions, easy disassembly, axial leads, visual instructions, etc.
10. Fuse holder features and reassessment: refer to manufacturer’s data sheet for information on clips, mounting blocks, panel mounting, PCB mounting, RFI shielding, etc.
11，Pre-production application test and verification: verify the selection by requesting samples to be tested in the actual circuit.Before evaluating the sample, ensure that the fuses have good electrical connections and that the cable connections used are appropriate.The test shall include a life test under normal conditions and an overload test under fault conditions to ensure the proper operation of the fuse in the circuit.
Post time: Oct-31-2019