What is "holding current"? (Resettable fuse / polyfuse)

Discussion in 'General Electronics Chat' started by daviddeakin, Mar 27, 2014.

  1. daviddeakin

    Thread Starter Active Member

    Aug 6, 2009
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    With regard to polyfuses, can someone explain to me the significance of the 'holding current'? The trip current seems straightforward- the current beyond which the resistance increases suddenly, but what is the holding current rating for?
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Could it be the maximum continues current ?
     
  3. t06afre

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    May 11, 2009
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    As I understand it the hold current is the current in which the fuse will be closed(not tripped). Polyswitchs are thermally activated. So any change in the temperature around the device will influence the performance of the polyswitch. As the temperature around the polyswitch increases, less energy is required to trip the device and thus the hold current decreases. Around room temperature the hold current is about 100% At -40 degree celsius the hold current is about 10% larger. But at 80 degree celsius you will find the hold current may be 50% lower than room temperature
     
  4. daviddeakin

    Thread Starter Active Member

    Aug 6, 2009
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    So do you mean that the holding current is a bit like a "minimum trip current" under maximum temperature conditions? In other words, under the hottest conditions, the trip point won't drop below the holding current rating?
     
  5. sirch2

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    Jan 21, 2013
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  6. t06afre

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    May 11, 2009
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    As the temperature around the polyswitch increase both tripping and hold current will decrease. Both hold and trip-current characteristics of polyswitch devices are a function of temperature.
     
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