New
P2026111016
Wirewound Power Resistor 27R 20W 5%
DZD 380.00
Power Resistors
92 results
Power resistors from 3 W to 25 W: cement, wirewound and ceramic resistors, for dissipating heat in power supplies, amplifiers and test loads.
Related categories
92 results
10 available
New
P2026111015
Wirewound Power Resistor 25R 20W 5%
DZD 380.00
New
P2026111014
Wirewound Power Resistor 24R 20W 5%
DZD 380.00
New
P2026111013
Wirewound Power Resistor 22R 20W 5%
DZD 380.00
New
P2026100950
Wirewound Power Resistor 470R 10W 5%
DZD 180.00
New
P2026100876
Wirewound Power Resistor 62R 20W 5%
DZD 380.00
New
P2026100875
Wirewound Power Resistor 40R 20W 5%
DZD 380.00
New
P2026100874
Wirewound Power Resistor 75R 20W 5%
DZD 380.00
New
P2026100873
Wirewound Power Resistor 33R 20W 5%
DZD 380.00
New
P2026100872
Wirewound Power Resistor 50R 20W 5%
DZD 380.00
P2026090806
Wirewound Power Resistor 47R 20W 5%
DZD 380.00
P2026090805
Wirewound Power Resistor 30R 20W 5%
DZD 380.00
P2026090804
Wirewound Power Resistor 20R 20W 5%
DZD 380.00
P2026090803
Wirewound Power Resistor 10R 20W 5%
DZD 380.00
P2026090802
Wirewound Power Resistor 1R 20W 5%
DZD 380.00
P2026090707
Resistor R47 7W 5%
DZD 70.00
Choosing a power resistor
A power resistor is chosen on three points: the value in ohms, the power dissipated in watts and the tolerance. The stated power (3W, 5W, 7W, 10W, 12W, 20W…) corresponds to dissipation in free air: in practice, allow a margin of twice the calculated power, especially in an enclosed case or near other heat-generating components. Ohm's law gives the actual power from the current and the voltage across the terminals.
The families available differ in their construction:
- Rectangular cement resistors (3W to 17W): the common, compact format, for power supply boards and snubbers.
- Wirewound in ceramic case (type RB57 SETA, G202, FP7): good resistance to brief overloads, useful for motor starting or current limiting.
- Large ceramic resistors (up to 245 mm): for test loads and braking, when a lot of heat needs to be dissipated.
- Porcelain heating resistors: designed to run hot, not for precise measurement.
For current-sensing shunts (0R68, 1R, R47), favor a tight tolerance, of the 1% type, as the error directly affects the reading. Wirewound resistors are inductive and are poorly suited to very high frequency. If a value is missing, the series-parallel calculation allows composing it, with the power then shared between the elements. For small signal values, see the Resistors category.
Frequently asked questions
What is the difference between a cement resistor and a ceramic wirewound resistor?
The cement type is a compact, molded rectangular block, for moderate dissipation on a board. The wirewound resistor in a ceramic body better withstands current spikes and high power, but it is bulkier and has parasitic inductance.
How do you choose the wattage of a power resistor?
Calculate the power with P = U×I or P = R×I², then choose at least double that as the rated value. A 5W resistor actually dissipating 4 W becomes very hot and drifts in value; a 10W used for the same job stays warm and lasts longer.
Can a 7W resistor be replaced with two lower-wattage power resistors?
Yes, in series or in parallel with suitable values, provided each element stays within its own limit. Two identical resistors in parallel give half the value and double the admissible power.
Why does the price of a power resistor vary so much?
The power rating, the body size, the technology (cement, wirewound, ceramic) and especially the tolerance make the difference: a 1% metal-film type costs more than a 5% of the same value.
How do you read a value written as 0R68 or 1K2?
The letter replaces the decimal point: 0R68 is 0.68 ohm, 1K2 is 1,200 ohms, 2K7 is 2,700 ohms. For models with color bands, use the <a href='/tools/resistor-color-code'>color code</a>.