Power resistor?

I should have also added the part must be through hole. And it's for a commercial product where UL certification is a must.

Take care..not only do you have to make sure the resistor can handle the watts...it must be rated to handle the voltage too.

I wouldn't worry too much about the type...that only really comes into play if you want good temperature/noise/stability characteristics.

I expect you're only worried about wattage, voltage, price and availability. (Usual rules apply ..e.g if it does everything you want...they aren't available. At KrisDel enterprises everything which is out of stock is half price)

Del

A "power" resistor is simply one that is designed to conduct high current in a relatively small resistor package. Typically, power resistors range from about 5W to kilowatts. Low power resistors are designed to withstand the heat generated by the I²R (power) loss but higher power resistors generally require auxiliary internal or external cooling by air, water, or other medium to dissipate the heat.

Suggest Googling "power resistor" for manufacturers, suppliers, and application information to help select the type that is best for your application.

You have forgotten to point out its (resistor) nominal in Ohm. It makes a HUGE sense for resistor's dimensions.

It makes a HUGE sense for resistor's dimensions.

Iv'e never noticed this in relatively low powered resistors... e.g 2W and less in the range of a few ohms to a few meg ohms.

Del

Hi Del, hope you enjoy your time spent in the garden.

I'm supposing that resistor nominal here from some 7.2 kOhm to dozens of MOhm make sense for resistor size restricted in dimension within 13 mm.

Though I can be wrong. In any case this resistor can't be Ohm it should be more than some 6.8 kOhm.

regards, caramba

As far as type, goes, I have found the "wire wound " resistors, as the most reliable, and slightly more accurate then the ones you mentioned.

Hear, hear! Unless they are run well beyond their nominal ratings, wire wound resistors are extremely reliable, and don't drift. At 60 Hz, their relatively high inductance can be safely ignored.

techno,

I agree with you regarding wire wound resistors being the most reliable. However, they may not be suitable in certain instances where the introduction of inductance can be a problem.

Agreed, however he is simply using it on an Input power line at 60HZ. There should be no problems. I believe it is where they are used the most.

Lots of Power resistors use ceramic materials to dissipate the heat.

you could use normal Resistors but then you would have to put a bundle of them parallel to get the required power value.

As far as i know, if you use uncommon values outside E24 series at higher power ratings than these power resistors are harder to come by.

"I now have to ask a foolish question."

What is the maximum current the resistor is expected to handle?

More information required.

As Sterling Stan has requested, what is the current draw.

Also it would be good to understand what other features are close by and what is the expected duty cycle.

We use Nichrome wire and make our own sense resistors for circuit board mounting, or even have a local spring manufacturer wind them for us. You may be able to find a gauge of wire that provides your exact resistace in 13mm length or close enough to have a pinched standoff with the wire a few mm from the board surface.

You still have a significant challenge with "through hole" application of a 2 Watt resistor. Some of the HEAT will be conducted through the leads to the board connection points.

My observations are that over time the solder will "change" and become extremely brittle and you will get cold joints. (Unless you have good heatsinking ground planes and such.) That's why you need to understand the duty cycle and other features on the board.

You may get UL approval for each of the components but in the combined system condition there still could be failure.