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Webinar Recordings

DC Motor Electrical Procedures

  • April 2020
  • Number of views: 685
Webinar recording bundle

A special discounted collection of 6 webinar recordings focusing on DC motor electrical procedures.

Just $30 for EASA members!

Carbon Brushes, Current Density and Performance

  • June 2019
  • Number of views: 497
Webinar recording

The lowly brush is underrated and misunderstood. The brush grade, brush pressure and spring tension, as well as the effect of load and humidity are each important to brush performance in DC machines, wound rotor motors, and synchronous machines.

DC Brush Neutral: What It Means and Interpreting Results

  • April 2018
  • Number of views: 770
Webinar recording

This webinar covers:

  • How much voltage output is too much?
  • What can cause higher than desired output voltage?
  • Brush spacing, brush seating, field or interpole spacing & polarity
  • Interpole circuits

DC Machine Inspection Report

  • August 2016
  • Number of views: 1636

A convenient incoming inspection report for basic DC motor conditions and test values.

Carbon Brushes and Commutation: A Practical Approach to Failure Analysis

  • June 2013
  • Number of views: 170
Convention presentation

Ever run across brush arcing or vexing commutation issues? This paper, presented at the 2013 EASA Convention, provides a approach to analyzing brush and commutation problems and failures.

Flashover: Causes and cures for damage to brushholders, commutators

  • April 2013
  • Number of views: 4226

There are times when a DC motor or generator experiences a catastrophic failure and the customer wants to know why it happened. One type of failure that seems to stimulate lively conversation is when the failure involves dramatic damage to the brushholders and commutator. The term "flashover" describes the appearance of the failure; the very name conveys an accurate mental image of the failure. The questions that arise next are predictable: "What caused this?" and "What can be done to prevent a recurrence?" Or, if the motor was recently repaired: "What did you do to my motor to cause this?!" The purpose of this article is to help you answer those questions.

Adjusting Brush Neutral

  • June 2011
  • Number of views: 537
Webinar recording

This presentation demonstrates how to set brush neutral in DC machines, describing several methods along with the benefits and drawbacks of each.

A case of uneven brush wear

  • October 1998
  • Number of views: 1644

The brushes on a 4-pole, 700 hp DC motor were not wearing at the same rate. In this case, rapid brush wear occurred on two adjacent brush rows - one positive and one negative polarity. The other brushes had minimal wear. Electrical tests found no winding faults, and the air supply was clean. Most of us suspect low current-density when rapid brush wear occurs. A lightly loaded DC motor can "dust" a set of brushes in short order. Changing the brush grade (or removing some of the brushes) will usually solve the problem.