Electrical Testing of Low and Medium Voltage Motors

To improve motor reliability and move to predictive maintenance for motors, tools are needed to assess the condition of the windings. There are several old and new test methods that have gained popularity with AC squirrel cage induction motor maintenance specialists. These include: ldr current signature analysis ldr growler ldr insulation resistance and polarization index ldr surge testing ldr partial discharge testing. The first two are applicable to find rotor winding problems, while the rest are intended for the stator winding. Each of these tests is critically examined and evaluated for: effectiveness; which windings/types of machines the test is effective; limitations; ease of performance and ease of interpretation. Recent changes to relevant IEEE and IEC standards concerning these tests are also highlighted.