Can anyone explain the cause and effects of power dissipations on resistors. I read a passage tht says " However, the wire-wound type is more rugged of two and able to survive much larger power dissipations than the carbon composition type." I don't under what this means. The only thing I can think of is using the two resistor types with greater current pass through each was designed for. The wire-wound will last longer before failing.
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Power dissipations?
- Thread starter EEC
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Power ratting of a resistor determines its failure point
Power ratting of a resistor determines its failure point
All resistor will generate a thermal response, which when superseding its wattage ratting will leave a open resistor. Some are more violent than others. Wire wound types will usually take much more power than a carbon resistor. The wire wound failure is normally much less violent. Think of a heater coil as a example of a wire wound resistor. Getting hotter and hotter until it opens the element. The carbon types can fail as burnt items on a circuit board or simply explode and just leave its ends soldered in the board.
Power ratting of a resistor determines its failure point
All resistor will generate a thermal response, which when superseding its wattage ratting will leave a open resistor. Some are more violent than others. Wire wound types will usually take much more power than a carbon resistor. The wire wound failure is normally much less violent. Think of a heater coil as a example of a wire wound resistor. Getting hotter and hotter until it opens the element. The carbon types can fail as burnt items on a circuit board or simply explode and just leave its ends soldered in the board.
broadgage
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Any type of resistor has a maximum wattage or disipation figure which should not be exceeded.
Although carbon resistors can be manufactured in high wattages, this is uncommon and higher wattage units are more often wirewound.
Carbon resistors over 1 watt are uncommon, wirewound ones are available up to hundreds of watts.
Although carbon resistors can be manufactured in high wattages, this is uncommon and higher wattage units are more often wirewound.
Carbon resistors over 1 watt are uncommon, wirewound ones are available up to hundreds of watts.
Many resistor wattage ratings are pretty optimistic. For example, I recently bought a 100 watt resistor. Specs indicate, however, that it can only dissipate 2.7 watts in free air. Pretty big difference. What many ratings mean is that with "adequate" cooling at low ambient temperatures, and for a few microseconds, you can dissipate the rated wattage without immediate destruction. And you thought derating wire was a bummer!
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