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How to Use Eddy Current for Conductivity Measurement?

In this blog post, you’ll read:Electrical conductivity meter can be effectively measured with eddy current instrument. We can apply electrical conductivity information to sort metals, and check for proper heat treatment and heat damage.

Table of Contents

A materials electrical conductivity information can be used to determine problems and defects on solid components. Electrical conductivity uses eddy current principle for accurate and fast material scanning.

This is the reason why choosing the right kind of eddy current electrical conductivity is of utmost importance and we have the right information you need to make an informed decision. But first, let us answer your questions about the importance of conductivity measurement, and how to get correct results when using a conductivity meter.  We will also give recommendations on some great quality conductivity meters for you to pick so please keep reading.



I. Importance of Conductivity Measurement


Electrical conductivity is used for checking the quality of materials by determining if the material can conduct electricity. It is used in process industries for both quality assurance and control to help determine if a material is fit for certain intended purposes.  Here are some of the important uses of electrical conductivity.

( If you want to get the right electrical conductivity meter with eddy current for measurement, here’s the right one for you. Click to learn more.)


  • To sort metals

Different metals have varied properties and therefore act differently when electrical current is passed through them.  Information on the conductivity of materials can be used to determine the composition of the materials being tested and you will therefore be able to sort the metals out depending on the conductivity properties.


  • To test resistivity of materials 

Resistivity can be loosely defined as the inability of a component to conduct electricity.  Materials that have high resistivity are poor electrical conductors.  Some industries, especially electrical and electronics engineering, require resistivity information for decision making purposes for the safe running of their daily activities.


  • To check for proper heat treatment 

Metals contain ions which react in certain special ways when they are heated.  During heat treatment of materials, ions get excited and move around inside the materials, this will cause a shift in the normal conductivity readings of these materials.  Through this information, you can deduce whether the heat treatment process has been well done. 


  • To inspect for heat damage

High heat can destroy or realign ions in certain kinds of metals.   Electrical conductivity measurement results will help you know whether any changes in a material have occurred and this could mean heat damage.



II. What do you need to Pay Attention to during Measurement? 


Electrical Conductivity Meter EE0011

Electromagnetic tests such as electrical conductivity use comparative methods to give accurate results.  The instrument will compare the values it gets against some stored values inside the device.  Because of this, there are some factors that you need to pay proper attention to, for your instrument to work optimally.  These are;


  • Calibration

As mentioned, conductivity measurements rely on comparison with already set values inside the instrument.  This can only be achieved through proper calibration, where a curve of known values is used in predicting the measured unknown values.  


  • Temperature

Magnetic ions inside a test component react differently under certain temperatures.  Therefore, conductivity values will be different on the same material in varied temperatures.  To control this, a temperature correction can be done whether automatically through instruments that have a temperature sensor or manually through temperature conversions.


  • Roughness

Proper eddy current measurement on rough surfaces is usually affected by the profile of the surface.  If a surface has grooves for example, the same probe placed on a dent or a peak will give different results.  To combat this, you need to take several readings on the same material then use the mean value as the conductivity value.


  • Curved surfaces 

The kind of surface of a test component may cause errors in conductivity or resistivity readings.  The instrument can give either higher or lower reading depending on the kind of surface that was used during calibration of the instrument.  For example, if calibration was done for a flat component, a curved surface (concave or convex) will give lower or higher figures than the true values.


  • The thickness of the testing part

Eddy currents move better in thick components to give good results. Movement of the current is very limited in thinner components and may give inconclusive results. To combat this type of error, pay attention to probe frequency values.


  • User influence

Some measuring errors can occur through improper use of the measuring device.  To avoid human operational errors, ensure the probe is placed vertically on the test surface and a stand can be used to avoid probe movement during measuring.



III. How to Select Your Metal Conductivity Meter?


The following are some factors that you need to consider when selecting a conductivity meter and probe for your specific conductivity testing needs. 


1. Determine your requirement

To choose the kind of electrical conductivity meter that is best for you, you first need to know what you require in terms of machine features.  Some important features are the quality of the instrument, the type of display, instrument speed, accuracy, and the type and size of power required to run the instrument.  In addition to this, it is also important to know whether you will use the instrument on the bench or out in the field.


2. Think about your application

Depending on your specific applications for conductivity measurement, there are some variables that you should be aware of to ensure your meter is fit for the expected purpose.  The requirements to look into are; measurement range, working temperatures, the type and size of materials to be tested, and performance requirements of the instrument.  Moreover, you also need to define the nature of the material that will be tested, be it a liquid or solid, a pure metal or metal alloys and so on.


3. Consider the flexibility of the operation

Because conductivity meters are versatile in measurement.  Check on the flexibility of your instrument to test different substances and to perform efficiently under varied temperatures. 


4. Select the right probe

An instruments’ probe is what determines the accuracy of the conductivity testing.  There are different kinds of eddy current probes that have been designed for specific purposes.  For example, a probe for checking electrical conductivity in water cannot be the same as a probe for metals and metal alloy examinations.  Probe specification details will help you understand what type of materials to use it on and the expected accuracy of measurement which is mainly influenced by the probe frequency details. 


5. Pay attention to the price and warranty

You may have chosen your conductivity meter with enough consideration to your applications and desired output and you may have even landed on the perfect instrument.  Now, check on the price of the instrument and instrument warranty.

 First of all, ensure that the price is affordable to your business.  Secondly, get an instrument that has a long period warranty 12 months and over is always a good choice.  Check that warranty is provided for both the conductivity meter and the probe.


6. Get to know the delivery date

The sooner a supplier can deliver your equipment the better it will be for you and your business.  Choose a supplier who does prompt delivery so that you can get your meter to start working for you as soon as possible.


If you want to buy quality but affordable electrical conductivity meter, you can consider importing eddy current conductivity meter for China. 



IV. Common Problems when Taking Conductivity Measurement


  • Get the improper probe calibration 

The ultimate test for how efficiently a conductivity meter probe will work comes down to how the instrument calibration was done.  Depending on the kind of work you use your instrument for, always pay attention to do the proper calibration.  In metal industries for example, the calibration standard should be one that has similar shape, thickness and surface quality as the components to be tested.

For example, if you are testing surfaces that are curved, use a curved surface standard to create the calibration curve that will be used for future testing on the same instrument


  • Neglect the temperature variations 

As stated earlier, temperature is a factor that greatly affects the conductivity of materials.  Ions present in a material move faster with increase in temperature. Failing to pay attention to temperature variations leads to inaccurate conductivity results. For example, in metal components, an increase in temperature results in increased resistance and therefore a decrease in conductivity.

Most manufacturers understand how important temperatures are for conductivity measurements and have therefore made instruments that automatically do temperature conversion to 20 degrees Celsius.


  • Wrong test on conductivity materials

Electrical conductivity using eddy currents is a versatile principle and works on solids and liquids alike. For measurement on solid components, you should pay attention to the type of material you are testing for conductivity.

For instance, conductivity measurement on pure metals is different from that of metal alloys and so the same test cannot be performed on these different materials.



V. Your Best Choice


Some great choices for conductivity meters by NDT-KITS that are fit for use in different industrial applications are as below.


Electrical Conductivity Meter EE0011

Electrical Conductivity Meter EE0011

The EE0011 electrical conductivity meter for metals uses eddy current principle for quick and convenient measurement of material quality in different industrial applications such as in checking for purity of materials, checking for conductivity on un-oxidized aluminum and checking for general material resistivity.  In addition to that, it is also used in the aviation industry to check on the strength of materials.

Features of the EE0011 meter include

  •       Operating frequency of 60 KHz which is a standard in the aviation industry.
  •         Allows for easy probe replacement and adjustment
  •         High power lithium battery for long operations
  •         Has data storage capabilities



Electrical Conductivity Meter EE0022

Electrical Conductivity Meter EE0022

The EE0022 is a meter that we designed with you in mind, because we know you want convenient and quick measurements.  It uses the eddy current principle for material quality assurance checking.  This conductivity meter has found use in applications such as testing for un-oxidized aluminum, material resistivity tests, testing for thermal performance of materials and so on.

Notable features of EE0022 are;

  •       Stores up to 1000 measurement data
  •         Operates at a frequency of 60 KHz to 120 KHz
  •         Has a high capacity battery for longer operations on the bench and in the field.
  •         Automatic temperature compensation of 20 .


➤ Related Article: How to Import Electrical Conductivity Meter from China? 





Eddy current conductivity measurement is important for checking material quality in various industrial applications.  This is why choosing the right conductivity meter is important.  There are key factors that you need to pay special attention to when choosing a conductivity meter and when doing quality checks using the same meter such as calibration and temperature variations.

No matter what your conductivity checking requirements may be, always get an instrument with the right probe that is affordable, has warranty for both the instrument and the probe and let it be from a supplier that will deliver your instrument in prompt time.

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