# Percent% Errror Quoted for Electrical Components. What is it?

• Phrak
In summary: Errror Quoted for Electrical Components. What is it?In summary, manufacturers quote a percent variation from nominal value for their parts. This percent error can be 5%, 1%, or 2%. If a part is quoted as 5%, the manufacturer guarantees that the resistors are within 5% of the nominal value. With better manufacturing tolerances, you can always sell higher-tolerance resistors as lower ones.
Phrak
Errror Quoted for Electrical Components. What is it?

(Where do I post electrical engineering homework questions? I'm home. I'm working. OK, maybe I'm not really working.)

Manufacturers quote a percent variation from nominal value for their parts. What does this percent error even mean??

For a 5% error, does this mean that each and every part is within 5% of the quoted value. Is the distributions flat, or is it Gaussian in shape?

If the manufacturer also sells a 2% version, does this mean that the 5% parts will have the middle 2% missing as these parts are selected-out?

Last edited:

Phrak said:
(Where do I post electrical engineering homework questions? I'm home. I'm working. OK, maybe I'm not really working.)

Manufacturers quote a percent variation from nominal value for their parts. What does this percent error even mean??

For a 5% error, does this mean that each and every part is within 5% of the quoted value. Is the distributions flat, or is it Gaussian in shape?

If the manufacturer also sells a 2% version, does this mean that the 5% parts will have the middle 2% missing as these parts are selected-out?

I believe that if you're quoted 5%, the manufacturer guarantees that the resistors are within 5% of the nominal value (at some given temperature)--otherwise, they'd go into the next resistor size! I seem to always get better though.

The reason you don't see the 2% chopped out of the 5% (and the 1% chopped out of the 2%, and so forth) is that resistors are sold in various series. There are more 2% nominal resistor values available (E48) as opposed to 5% (E24) and 10% (E12):
http://en.wikipedia.org/wiki/Preferred_number

With better manufacturing tolerances, you can always sell higher-tolerance resistors as lower ones.

MATLABdude said:
I believe that if you're quoted 5%, the manufacturer guarantees that the resistors are within 5% of the nominal value (at some given temperature)--otherwise, they'd go into the next resistor size! I seem to always get better though.

The reason you don't see the 2% chopped out of the 5% (and the 1% chopped out of the 2%, and so forth) is that resistors are sold in various series. There are more 2% nominal resistor values available (E48) as opposed to 5% (E24) and 10% (E12):
http://en.wikipedia.org/wiki/Preferred_number

With better manufacturing tolerances, you can always sell higher-tolerance resistors as lower ones.

That makes some sense. It may depend on the manufacturing process; upon whether a part is tested or not. Without testing, periodic process checks would be preformed to see that process parameters are within limits, such that tolerance limits are met in the final product. In this case you'd expect a small fraction of items to leak outside the tolerence limits. So the curve might be more or less a normal distribution. With 100% testing, those that exceed spec would be kicked out. In this case the distribution would be normal, with the tails of the curve truncated.

It also depends on the quality of the people. I've worked for some crap companies, whos specs were bogus.

But this is a lot of semi-educated guess-work on my part. Wish I knew better.

## 1. What is percent error quoted for electrical components?

Percent error quoted for electrical components is a measure of the inaccuracy of a measurement or calculation in relation to the true or expected value. It is expressed as a percentage and can be used to assess the quality and reliability of electrical components.

## 2. How is percent error calculated for electrical components?

To calculate the percent error for electrical components, you need to subtract the measured value from the expected value, divide this difference by the expected value, and then multiply by 100 to get a percentage. The equation for percent error is: (|measured value - expected value| / expected value) * 100%

## 3. Why is percent error important in the field of electrical engineering?

Percent error is important in the field of electrical engineering because it helps to identify the accuracy and reliability of electrical components. It also allows engineers to make necessary adjustments or improvements to ensure the highest quality and efficiency in their designs and systems.

## 4. What factors can contribute to a high percent error in electrical components?

There are several factors that can contribute to a high percent error in electrical components, including measurement errors, manufacturing defects, environmental conditions, and human error. It is important to identify and address these factors to improve the accuracy and reliability of electrical components.

## 5. How can percent error be minimized in electrical components?

To minimize percent error in electrical components, engineers can use more precise measurement techniques, conduct thorough quality control and testing during manufacturing, and consider factors such as temperature and humidity during design. Regular maintenance and calibration can also help to reduce percent error in electrical components.

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