Test Descriptions Test Descriptions
Demands in today's industry require motors to run as often as possible. Most proactive companies want to employ predictive maintenance practices on their motors. However, this valuable act can be a double-edged sword-important to do, but often requiring the motor to be shut down for access. Finally, there is monitoring equipment available that gives you the best of both worlds. Emax, from PdMA Corporation, is a portable dynamic tester that evaluates electrical motor condition without shutting down your process.
The power analysis portion of the equipment provides valuable insight into incoming power quality, power circuit condition, stator health and motor efficiency. The three phase current and voltage signal is captured in less than a minute and stored for diagnostics and trending.
Utilizing a combination of unbalance parameters and harmonic analysis, Emax examines the power signal for indications of defects within the different fault zones. Power quality is diagnosed using total harmonic distortion (THD) and crest factor (CF) calculations. Distortion in the signal, often the result of nonlinear loads, produces additional heat within the motor that will reduce life if not acted upon.
The power circuit and stator are evaluated through the use of unbalance parameters and sequence data. Unlike the positive sequence currents that produce useful torque, negative sequence currents are caused by high resistive connections within the motor or circuit and generate heat-producing counter torque. Rising negative sequence currents coupled with a high impedance imbalance is indicative of developing stator faults.
Current analysis is performed through a combination of spectral graphs and software automation. Utilizing this portion of the equipment, the user can identify defects in the rotor and air gap fault zones and record motor startup.
Current is collected in one of three ways: high resolution, low resolution or eccentricity. Each uses different sampling rates and resolutions to identify anomalies in a specific fault zone. Rotor bar defects and eccentricity, static or dynamic can be detected and trended.
Startup, arguably the most stressful and informative time in motor operation, is recorded from start to finish. Graphing in-rush current and start-up time is extremely valuable when evaluating motor operation and condition. Changes in the startup characteristics can be attributed to rotor or stator faults.
Trending data is a critical element in any condition monitoring process. But, spotting motor trends is most effective if the data collected can be organized and viewed as quickly and efficiently as it's captured. Emax generates valuable reports immediately after testing, enabling you to assess the condition of your motors in the field or trend the data for later use.
Emax reports include a series of graphs, screen plots and historical comparisons. These reporting capabilities clearly illustrate the status of rotors, stators, power quality and other fault zones, allowing you to discover and evaluate possible problems before they result in lost productivity from forced downtime.
In addition, when combined with the MCE, the Emax provides the most comprehensive condition analysis equipment available in a single package.
Finally, with the professionals at PdMA Corporation behind this product, you can always rely on our expertise and technical support. Call on us for assistance in maximizing your electrical reliability efforts.
For more information on Emax, or to see a demonstration, please call (800) 476-6463, or e-mail us.