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Understanding How a DLRO Measures Low Resistance

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Low resistance measurement can help you determine the internal condition of electrical connections. Ideally, a good metal connection should have a very low resistance to current. However, if the joint corrodes, weakens or get contaminated, the resistance increases. This test lets you find defects that are not normally visible through visual inspection. This diagnostic method is also suitable for finding weak joints in welded metals like in airplanes and railroads.

In measuring very low resistance, an ordinary Ohmmeter will not do. The proper device used for this application is a microOhmmer or digital low resistance Ohmmeter. A DLRO applies a very high current of at least 10 amperes to the test sample and measures the voltage drop across. The measured voltage is then used to compute for the resistance using Ohm’s law. This device often utilizes a Double Kelvin Bridge input to offset the lead resistance. This input configuration ensures accurate resistance measurements. 

If you are looking for electrical test equipment for low resistance measurement and other diagnostic procedures, consider getting them from Protec Equipment Resources. Please contact us at 1-866-352-5550 for a complete list of test equipment available in our inventory.