Ok Take the following facts:
Nominal Resistance = 360 Ohms
Tolerance = 5%
Maximum Permissible Resistance = 378 Ohms
Minimum Permissible Resistance = 342 Ohms
Now Assuming the resistor above is rated at 2 watts, what is the maximum continuous Voltage that can be placed across the resistor without causing it to overheat?
How do we find this?
If anyone can help, It wouldl be greatly appriciate it. Thank You
2006-11-30 03:29:39 · 3 answers · asked by ? 2 in Science & Mathematics ➔ Engineering
The math is correct for the above answers but since you asked the question with regards to overheating there are other considerations.
The major enemy of all electrical and electronic components is heat.
Resistors are rated at ambient temperature of 25 degrees C. This rating is in free air with component leads connected to a substantial terminal that can help carry heat away.
If you operate this resistor at maximum rating and put it in an enclosure it will fail long before expected.
Manufacturers tend to exaggerate their ratings and test them in ideal but not realistic conditions. A resistor that may hold up running at maximum ratings will soon fail when subjected to the thermal cycling in and out of this extreme temperature condition.
A rule of thumb that is practical is to size a resistor at 1/2 of its wattage rating unless there are only short duration high wattage peaks. Damage doesn't occur until it has had time to come up to temp. If you are interested in long component life operate components at well below their maximum.
2006-12-04 01:29:23 · answer #1 · answered by Buffertest 3 · 1⤊ 0⤋
Power through the resistor is V^2/R. Set Power = 2, R = to it's lowest possible value and solve for V. (^ = exponent operator).
2006-11-30 11:33:40 · answer #2 · answered by Gene 7 · 1⤊ 0⤋
Watts = (voltage)^2 / Resistance so.....
Voltage = SQ. root of (watts*resistance)
Max = Sq. root of (2 watts * 378 ohms)
Min = Sq. root of (2 watts * 342 ohms)
2006-11-30 12:05:31 · answer #3 · answered by digger 1 · 1⤊ 0⤋