I am trying to decide on the best resistor type for a 50V system with ~470 Ohm resistance. This resistor will constantly be dissipating power.

Is a wirewound resistor the right choice? Should I be looking into planar resistors? And how can I determine when a heatsink is necessary for a resistor.

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    \$\begingroup\$ What's the requirement context? Wirewound resistors are the easiest way to dissipate larger amounts of heat, since the ceramic conducts heat but not electricity. Carbon, even in a thin film on ceramic, doesn't lose the heat to it as easily as copper. However, the wirewounds have a lot more inductance, so you have to take that into account depending on the frequency range you're using. \$\endgroup\$ – Cristobol Polychronopolis Dec 4 '18 at 21:44
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    \$\begingroup\$ For long life you want it to be rated for 15 to 20 watts. Ceramic wirewound is the toughest, but has substantial inductance. From here the price goes up with better materials like silicone. Panel mount resistors need a heatsink but offer absurd precision (.1% -> .01%) if you need that, and do not mind the high cost. Please give us more details of what you actually need. \$\endgroup\$ – Sparky256 Dec 4 '18 at 21:59
  • \$\begingroup\$ @sparky256 the OP appears to have already de-rated. 50V across 470R = 5.3W. so a 10W could be appropriate for the OP with life and derating \$\endgroup\$ – JonRB Dec 5 '18 at 0:45

When in doubt, use a distributors parametric search option. Typically wire-wound are needed


10W, 470R.

I personally have an affinity for metal-clad resistors or the green metal wound for this type of loading

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    \$\begingroup\$ I wouldn't use a 10W rated resistor at 10W... But perhaps I'm overly cautious. \$\endgroup\$ – Hearth Dec 4 '18 at 23:13
  • \$\begingroup\$ Neither would I ... I would easily do a 70% de-rating (ie at least 15W) IF I needed to dissipate 10W, I don't think the OP does. The OP was asking for specifics as what/where. The OP may have factored in de-rating: 50V @ 470R = 5.3W, thus requesting a 10W resistor for such loading seems fine \$\endgroup\$ – JonRB Dec 4 '18 at 23:14

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