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This new video provides a guide on performing a single-phase rotor test on a three-phase squirrel cage motor to check for open rotor bars. It begins with an introduction to the test's purpose and the importance of ensuring the stator winding is free from grounds, shorts, or opens by conducting preliminary tests such as insulation resistance, surge, and lead-to-lead resistance tests. The video then details the identification and setup of the necessary test instruments, including a single-phase power supply, digital voltmeter, and clamp-on amp meter.

The procedure involves correctly connecting the stator for the test, applying single-phase voltage, and measuring the maximum and minimum amperage during the test. By rotating the motor shaft manually and monitoring the current with a clamp-on amp meter, viewers can note the highest and lowest current values. The video explains how to calculate the test current variation and interpret the results to determine if the rotor has open bars.

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The new EASA Learning Center is now online and ready to provide industry-specific training. You are now able to provide your employees with access to much of EASA's training without leaving your service center! Access to EASA’s Online Learning Center is sold as 12-month subscriptions and targets employees of all skill levels.

ERT Certificate Program
Also delivered through the EASA Learning Center is the new Electromechanical Repair Technician (ERT) Certificate Program. The ERT Cetificate Program provides new, existing, and potential employees in the electromechanical repair industry a structured learning path to become a well-rounded, service center technician. 

EASA LEARNING CENTERERT PROGRAM

Most of us do not have the facilities to load test large DC machines, so our AC method to set brush neutral depends on how well the factory tuned the interpole strength. When a machine has interpoles that are a bit too strong or too weak, revert to this on-site method to locate the correct brush neutral position:

• This is a trial-and-error process, so don't get discouraged if it's not perfect the first time.
• Run the motor at load, and observe the arcing.
• Shut it down and lift a few brushes to make sure they are all burning on the same edge. (Leading or trailing doesn't matter, just confirm it's the same edge for all brushes.)
• Shift the entire brush rigging about ⅛" – ¼” (3-6mm) away from the burning edge. That will be closer to the "working neutral" position.
• Lightly use the brush seater to clean the brush faces.
• Run the motor at load again and see if it sparks; if it doesn't spark, then you got it in one try – congratulations!
• If it still sparks, repeat the steps above. Shift the brush rigging away from the burning edge.
  –  If the burning shifted to the other edge, you moved it too far, so move it back a little bit.