Capacitors are among the most important components of all and can be found in numerous electronic devices, from laptops to washing machines to smartphones. If you want to measure a capacitor, for example to determine its capacity, multimeters are a good choice. The correct procedure is important, because only in this way can the exact values be measured without complications.

A capacitor is used to control essential functions in electrical appliances. It functions, for example, as an AC resistor or can be used as a memory. The function of the capacitor depends on its use within the circuit and it is most frequently used in DC circuits, but is also less common in AC circuits. Over the life of the device, capacitors wear out, which can cause the function to suffer, resulting in problems with the electrical equipment. Typically these do not store enough energy, which has a negative effect on the use of the device. A multimeter is used to check the condition or the exact capacity of the capacitor and can give you information about it.

Important sizes
Before you use the measuring instrument, you should know the most important quantities to be able to measure with the capacitor. These are the values that help to determine the functionality of the component and show you exactly whether it can still be used.

1. electrical capacitance: the electrical capacitance is given in C and indicates the maximum amount of charge of the capacitor. It is measured in Farad and defines how much energy the capacitor can store.

2nd Farad: Farad is the unit of measurement for the electrical capacitance and is given in F.

3rd resistance: the resistance is measured in ohms. It is necessary to measure the resistance of the capacitor to determine whether it is still working or charging.

These values help you to make the correct settings to measure the capacitor.

If you do not yet have a multimeter, you must of course first obtain a suitable measuring device before you can use it. You have the choice between the following functions.

Devices without capacity measurement: 10 to 15 Euro
Devices with capacitance measurement: 20 to 40 Euro
The devices look the same at first glance, but the multiple measuring device with the additional capacitance measurement offers the possibility to determine the electrical capacitance of the capacitor. This allows you to see exactly how high the capacitance is and whether it is sufficient or still in factory condition. As soon as the capacitance of the capacitor decreases due to wear, the function suffers and a replacement capacitor is required.

In the case of a device without capacitance measurement, it is only possible to determine the operability, since this carries out a pure resistance measurement. This means that the more accurate you want to measure, the more important it is to use a multimeter with capacitance measurement.

1. remove the capacitor from the circuit for measurement. To do this, terminate all contacts so that the poles are exposed.

Then check the component for possible damage.

This includes:

3. finally, you must discharge the capacitor. This is important because there may be residual current in the component, which has a negative effect on the measurement results and, in the worst case, may even damage the measuring instrument. To discharge, connect the capacitor to an electrical load. This step is particularly easy with a light bulb. After the residual current has been discharged, you can measure the capacitor.

Tip: Multimeters for industrial applications are also available on the market, which can be used for numerous measured variables and are significantly more expensive. Such models are not necessarily required for the home, as only a few measured variables are used.

leaking liquids
If this is the case, the capacitor is usually irrevocably damaged and should be replaced. Especially in the case of large dents or loss of liquid, a new capacitor should be used, while particularly fine cracks are usually still functional, but should be replaced at the next best opportunity.

Measuring instructions
Measuring a capacitor with a multimeter without capacitance: Instructions

After the preparation you can now measure the capacitor. The following variant is not quite as accurate as measuring the capacitance, but is sufficient to see if the capacitor is still working at all. Apart from the multimeter, you do not need any other tools to perform the measurement.

Follow the instructions to measure the capacitor:

Step 1: At the beginning you adjust the instrument without connecting the measuring leads to the capacitor. The instrument is set to a value of 1 kiloohm, i.e. 1,000 ohms. To do this, turn the handle until the marking arrives at this point. However, do not switch on the device yet.

Step 2: Connect the test leads to the multimeter. The majority of the devices have detachable measuring ladders, but there are some cheaper models that have these permanently installed. Connect the device.

Step 3: Then connect the test leads to the poles of the capacitor. As soon as the circuit is closed, a value should appear on the display for a short moment, which you should remember and note for safety’s sake if you are not so good with numbers.

Then the command “OPEN LINE” is displayed. Now repeat this procedure one more time. If the same value appears as before, everything is fine with the capacitor. However, if the result is different, the capacitor is damaged and must be replaced. In many cases it will not charge up.

Measure capacitor capacitance: manual

With this variant you measure the capacitance of the capacitor, which you can compare with the values of the manufacturer. Proceed as follows:

Step 1: Set the multimeter to capacitance measurement in Farad. This is marked with a C on the multimeter and the measuring range is optimally adjusted by the instrument itself. To do this, the instrument must be switched on and the measuring leads connected.

Step 2: Connect the two measuring conductors to the poles of the capacitor and compare the indicated capacitance on the capacitor with the displayed value. If the measurement result is similar, the capacitor can be used. If the value is significantly below the standard value, the capacitor can no longer be used and should be replaced.


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