Can the method of paralleling small-capacity fuses be used to achieve the purpose of fast fusing?

Power Circuit Protection
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Question: Can you use multiple fuses with small current ratings in parallel to increase the response time of a fusing system?
Answer: Generally, paralleling fuses can increase the rated current for the fusing system. As for the fusing speed, it mainly depends on the T-C curve and I²t.

  • Under normal circumstances, paralleling fuses will increase the overall rated current. This is because the total current in a parallel circuit is the sum of the currents in each branch. For fuses, the upper limit of the current they can withstand will increase after being paralleled.

  • The key factors affecting the fusing speed of fuses are the T-C curve (time-current characteristic curve) and I²t (Joule integral).

For example:

DigiKey Part Number WK6213BK-ND
Manufacturer Littelfuse Inc.
Manufacturer Product Number 38216300410
Detailed Description 6.3 A 250 V AC DC Fuse Board Mount (Cartridge Style Excluded) Through Hole Radial, Can, Vertical
Datasheet Datasheet

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According to the datasheet, the following is the T-C curve.

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The T-C curve describes the time required for the fuse to blow under different overload currents. Through this curve, the relationship between the current magnitude and the fusing time can be visually observed.

  • I²t is an energy-related parameter, which reflects the amount of current energy passing through the fuse within a certain time.

On the DigiKey website, the I²t parameter can be easily found.

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This parameter is also very important for judging whether the fuse will blow and the fusing speed. That is to say, simply paralleling small-capacity fuses has little effect on fusing response time and cannot easily achieve the purpose of fast fusing; these key parameters also need to be considered.

More Littelfuse circuit protection products

Littelfuse Circuit Protection products provide stable and reliable signal transmission guarantee for all kinds of precision electronic devices by virtue of their precise adjustment relationship with capacitance, dynamic resistance, etc. in terms of high-frequency characteristics, and their performance is excellent in the industry.

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  7. Can the method of paralleling small-capacity fuses be used to achieve the purpose of fast fusing?

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