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 What are the Methods of Testing an Electric Motor

What are the Methods of Testing an Electric Motor

Sunday, August 14, 2022

IEEE Std 1415-2006 IEEE Guide for Induction Machinery Maintenance Testing and Failure Analysis

This is a complete list of Motor Tests as Listed under the IEEE std, with associated experience from 3Phi Reliability.

Bearing Temperature Simple trending, Better Methods for on condition Lubrication. 3Phi Reliability recommend using SDT Lubexpert for on condition measurement of friction levels and optimal Lubrication.

Capacitance  Ok for contamination of Windings3Phi Reliability recommend measuring Capacitance as a trend and Dissipation factor. These two measurements provide good understanding of the Insulation contamination.

Core Loss Test  Essential in the rewind process, Conducted in the repair shop.  3Phi Reliability recommend specifying Core Loss test before & after burn out to ensure the stator core is suitable for a rewind.

Current Trending   Ok if the process is stable

Current Signature Good tool but drive Emissions can crowd data.

Current Starting In Rush current amplifies Winding condition defects, the meter must have Low Pass filter and variable Hz capability for Drives.

DC High Potential   Limited Experience No Comment

Dielectric Similar to Polarisation Index. Good on Open frame motor near Ammonia. Should only conduct this test if Insulation Resistance is less than 5 Giga Ohm.

Dissipation Factor Cable defects can be detected. Motor Insulation aging can be identified.

Grease Analysis This is essential part of a Lubrication program, especially on Drives where Electrical decay can occur.

Growler Signature Workshop Rotor Analysis. In field Rotor Tests ans Acceptance testing best conducted with Dynamic Rotor Test

Insulation Resistance Mandatory Safety Test. Tends to be a late stage detection test. Conducting Phase to Phase Insulation test may show earlier defect. Must be corrected for temperature.

Oil Analysis Very Effective early stage defect detection.

Partial Discharge Essential for MV & HV Assets

Phase Angle Effective detection of early Winding defects. Measured in combination with Inductance and Impedance.

Polarization Index Effective Method of Insulation health. Does not need to be Temperature corrected.

Shaft Grounding Currents  More effective than Shaft Voltage. Measured with Rogowski coil and Scope.

Shaft Voltage Good Indicator of Drive Emissions

Speed Ok for measuring Slip frequency if load constant. Errors are high and ha been withdrawn from IEEE std.

Surge Test Effective Winding Test. Not easily portable. Good for detection of winding defects in first turns of a coil. Limit success in for deep coil defects depending on test voltage. High test voltages risk damage if ground wall condition comprimised.

Torque Analysis Portable Good Analysis, takes alot of setup. Not really portable.

Thermography Good general tool. Limited to Line of sight

Ultrasound Great for On Condition Lubrication programs

Variable Frequency  Effective early detection of Winding defects. Portable.

Vibration Analysis Effective in many Motor defects Mechanical and Electrical. Limited Stator defect detection.

Voltage Balance Essential Test Highly damaging to Stator health

Voltage Distortion Power Quality should be checked with Power Analyser, can affect Motor Efficiency

Voltage Drop As above on Motor Start

Voltage Level As above

Voltage Spikes As above

Winding Resistance Effective means of Circuit defects and Energy Opportunities

Winding Temperature Good trending indicator. Copper losses elevated with temperature.


EMF Drive Emissions  Good indicator to Winding decay, Lubrication decay, and Bearing damage

Transfer Impedance Verification of Drive/Motor grounding to minimize Bearing currents.

Mark Gurney Motor Analyst 3Phi Reliability SARL

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