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How a DLRO Detects Faults in Welded or Bonded Metals

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Digital low resistance ohm meters are handy test tools for measuring resistance between two welded metals. An increasing resistance value of two metal contacts is an indicator of degradation. This can quickly alert the operator of any significant changes on the condition of metal joints and immediately perform corrective actions to prevent further damages.


DLRO measures resistance by passing a current through the test sample and measuring the potential across the sample. It is then internally calculated by the tester using Ohm’s law to determine the resistance of the sample.

Welded or bonded metal joints like rails, ground bonds, circuit breaker contacts, squirrel cage bars and other devices can be degraded and can only show obvious physical damage when damage is already extensive. DLROs can detect changes in the resistance of welded joints and any significant change may indicate degradation. Early detection helps restore the degrading part and prevents unexpected breakdowns. 

If you don’t have the right test equipment or don’t have the budget to buy the equipment you need, consider test equipment rental options from Protec. We have high voltage equipment available for rent from known manufacturers. Call us now for a quote on test equipment rental.