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How to schedule

To schedule private education for your group, contact:

Dale Shuter, CMP
Meetings & Expositions Manager
+1 314 993 2220, ext. 3335
dshuter@easa.com

1 hour of training

$300 for EASA Chapters/Regions
$400 for member companies
$800 for non-members

How a webinar works

All EASA private webinars are live events in which the audio and video are streamed to your computer over the Internet. Prior to the program, you will receive a web link to join the meeting. 

The presentation portion of the webinar will last about 45 minutes, followed by about 15 minutes of questions and answers.

Requirements

  • Internet connection
  • Computer with audio input (microphone) and audio output (speakers) appropriate for your size group
  • TV or projector/screen

Zoom logo

The Zoom webinar service EASA uses will ask to install a small plugin. Your computer must be configured to allow this in order to have full functionality. Please check with your IT department or company's security policy prior to scheduling a private webinar.

Private Webinars

EASA's private webinars are an inexpensive way to bring an EASA engineer into your service center, place of business or group meeting without incurring travel expenses or lost production time.

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Article

Identifying and getting to root cause of shaft currents

  • February 2015
  • Number of views: 4835
  • Article rating:

Pat Douglas Kirby Risk
Mechanical Solutions & Service

Shaft currents have always been a concern for large motors due to magnetic asymmetries within the motor. Manufacturers strive to keep these to a minimum.

With the widespread use of Variable Frequency Drives (VFDs), shaft current issues have become a concern in all sizes of motors. If these currents are discharged through the bearings, electrical discharge machining (EDM) occurs. Proper installation of VFDs can play a large part in mitigating issues with shaft currents. 

Many end users are not aware of shaft currents or their destructive paths. All too often they think that the motor bearings keep failing because the motor repair was not completed properly. 
Service centers need to be on the lookout for these issues when repairing a customer’s equipment. Many repairs arrive at the service center with no history and no hint of what the problem with the motor might be. The technicians have to do an “autopsy” of the motor to be sure the causal problem is repaired and not just the symptom.

Available Downloads



EASA Technical Manual

More information on this topic can be found in EASA's Technical Manual
  • Section 2: AC Machines
  • Section 8: Bearings

Related Reference and Training Materials

Principles of Medium & Large AC Motors (NEMA Standards)
  • Section 10: Bearings & Lubrication

Principles of Medium & Large AC Motors (IEC Standards)
  • Section 10: Bearings & Lubrication

Root Cause Failure Analysis
  • Section 2: Bearing Failures

Mechanical Repair Fundamentals of Electric Motors
  • Section 13: Shaft/Bearing Currents

Tags: Shaft currents Shaft voltage
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