Detecting Transformer and Motor Problems with a DLRO

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Low resistance measurements can give a lot of information on the condition of the tested part. Loose or corroded connections can increase its baseline resistance. The common testing tool used for this is a DLRO. This can be used to test small, medium, large single phase, large multi-phase, auto-transformers and motors. It can also be used to detect weak connections of terminals and motor commutator bars. 


An ideal tester should have sufficient current to saturate the coils. If the current is too low, you can get inaccurate results. You should also allow the test sample to cool down because hot coils will have a different resistance reading. You should make sure that the contacts are firmly connected the test sample for maximum delivery of the test current. It is recommended to use kelvin clips or helical spring point test leads to cut through any grease or contaminants that might be present on test sample. These contaminants can alter your reading making it inaccurate.

Regular testing of transformers and motors can prevent unexpected delays. If you are looking for atest equipment rental service, consider renting equipment from Protec. We also carry various high voltage test equipment from leading brands. Contact us for more information on our services.