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Rotor Bar Testing – Digital Low Resistance Ohmmeter (DLRO)

Test Overview

During a DLRO test, resistance measurements are taken across single rotor bars and then evaluated (relative to other bars from the same rotor) for values above an acceptable range. 

Test Deficiencies

Although DLRO testing is an effective method of evaluating rotors for cracked/broken or otherwise damaged/defective rotor bars, the test methodology has its shortcomings. In the case of a die cast rotor, the rotor must be modified to access the individual rotor bars, creating extra work for repair technicians. In addition, the DLRO test doesn’t necessarily provide a definitive pass/fail; it can raise more questions than answers.