What Does ESR Stand For In Capacitor?

Capacitors are an essential electrical component in the design of many electrical devices. What Does ESR Stand For In Capacitor? For devices like microprocessors, capacitors must be carefully selected to ensure the best performance.

Choosing the right capacitor for the design requires electrical designers to know about ESR. The best ESR meter is an important quantity for capacitors.

So what does ESR stand for in capacitor, and why is it important? This article’s purpose is to answer that and help you understand the concept of ESR and its importance.

What Is ESR?

ESR stands for Equivalent Series Resistance. Ideally, or in theoretical conditions, a capacitor is only considered to have a best capacitance meter. However, that is not the case in practical conditions.

In practical conditions, a capacitor has some resistive properties. So, in reality, a capacitor does not act as a pure capacitor. When designing, this resistive property is taken into consideration by taking an ideal capacitor along with a resistance in series.

This resistance is known as ESR. The ESR arises because of the dielectric materials that are used to construct a capacitor. As a result, the ESR varies between capacitors. The quantity is also frequency dependent.

Why Is ESR Relevant?

Seeing this small resistive property might make you wonder, why is it even relevant? Isn’t it small enough that it can be ignored? In simple electronic circuits that don’t make use of many capacitors, the value is small enough that it doesn’t have an overall effect on the circuit.

However, in complex devices that are used in conjunction with high power or frequency settings, the ESR value has a greater impact. There are more capacitors in place, and not considering ESR can result in reduced efficiency or the device not operating as expected.

So for an electrical engineer to ensure their electrical device is working properly, ESR is an important value to consider. With it, you can model the complete behavior of a capacitor and ensure your calculations are correct.

What Does ESR Stand For In Capacitor?

ESR Stand For In Capacitor

A capacitor charges and discharges electricity. The time it takes to charge up and the time it takes to discharge entirely depends on the capacitor’s capacitance along with the ESR.

Generally, in most cases, you want this time to be lower so the capacitor can react faster to changes in voltage or current. A lower ESR value means the time taken for a capacitor to charge up is less.

Lower ESR is also good because it means that less energy is lost as heat, so the capacitor does not cause a decrease in inefficiency. So a capacitor with low ESR is usually more responsive.

What Does ESR Depend On?

The ESR value of a capacitor can vary depending on the material of the capacitor. Aluminum electrolytic capacitors tend to have much higher values of ESR than polymer capacitors.

Since ESR is an AC resistance, the resistance value is not fixed. It changes with frequency, and so higher frequency circuits will experience the effects of ESR more.

So ESR can depend on the following factors:

  1. The material used in the construction of the capacitor.
  2. Frequency of the power source used with the capacitor.
  3. Surrounding temperature of the capacitor.

Age Of A Capacitor And Its ESR

Another thing to choose a ESR meter note about it changes with age. As time passes ESR of a capacitor will increase.

For Aluminum electrolytic capacitors, this is a huge problem as the increase in ESR can make the capacitor useless if it increases past a certain point. High temperatures can end up decreasing the life span of these capacitors.

Polymer capacitors have lower ESR values and thus can last a long time. They can handle temperature changes better and are easier to work with in most cases.

ESR And Frequency

In regards to frequency, the ESR values of capacitors tend to show a general decrease as frequency increases.

The decrease in the resistance value varies wildly depending on the capacitor in question. Some show a very rapid decrease until the resonant frequency is reached, while others show a much slower decrease.

Measuring ESR

So now the important question is, how to use ESR meter to measure ESR. As discussed above, ESR is an AC resistance. Multimeters cannot be used to measure ESR. How to Test a Capacitor with a Multimeter?

There are instruments known as ESR meters that make use of alternating currents. So they are designed to be able to measure the ESR of a capacitor without having to separate the capacitor or de-solder it.

When measuring with an ESR meter, do remember to note down the resistance for a particular frequency. ESR changes with frequency. For most capacitors, the value ranges from several milliohms to ohms.


After reading this, we hope that you now know what does ESR stand for in capacitor. When working with complex devices, failure to consider this resistive property can result in unexpected responses or devices not working. Knowing about ESR will help you make better designs.

Source Link:

  1. https://en.wikipedia.org/wiki/ESR_meter

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