Fuse Knowledge
May 21, 2022
1，Relationship between fusing time and temperature rise
Under the same fault current, the shorter the fuse blowing time, the higher the internal resistance of the fuse and the higher the temperature rise.
2,What is the meaning of I2T curve, arc voltage curve and power consumption curve?
1) The I2T curve means that the energy value (I2t) required for the fuse to break under different voltage systems is different,
Different conversion factors correspond to different voltages.
2) The arc voltage curve refers to the
The arc generated inside the momentary fuse is broken under the voltage system
Voltage value (also known as operating overvoltage).
3) The power consumption curve refers to the power consumption exhibited by the fuse under the rated current and different voltage systems.
Power consumption is different, expressing the change curve of power consumption.
3,How to choose a suitable fuse?
This should be based on the actual application conditions, voltage selection fuse rated voltage 2 system maximum voltage. The selection of the rated current of the fuse is a little more complicated. It is necessary to know the rated current of the fuse, the inrush current of overload and surge, time, frequency, the cross-sectional area of the busbar connecting the fuse, the start-stop cycle of the whole machine, and many other factors. , Anything that can affect the heat dissipation and heating conditions of the fuse will change the electrical characteristics of the fuse.
◆As far as the EV industry is concerned, the rated current selection of fuses based on experience is roughly as follows:
- The fuse is used to protect the main circuit of the battery pack (not placed in the MSD), generally 2 times the rated current;
If it is placed inside the MSD, it is generally 3-4 times the rated current. If it is placed inside the PDU, the branch circuit protection is generally 2-3 times the rated current. However, the above is only suitable for general models. For sports cars, high-current fast charging, high-power special vehicles, etc., you have to further consider the detailed selection calculation.
