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EASA Technical Manual

  • September 2022
  • Number of views: 27473
  • Article rating: .5
FREE for Members of EASA

Revised September 2022!
EASA's most comprehensive technical document is available FREE to EASA members. Download the complete manual or just the sections you're interested in.

EASA AR200-2021: Guide For The Repair Of Dry-Type Transformers

  • August 2021
  • Number of views: 10384
  • Article rating: 3.8

This guide outlines best practices for the repair of dry-type transformers.

Transformer basics: How they operate, their many features

  • April 2014
  • Number of views: 6388
  • Article rating: 3.0

Transformers are fundamental to an industrial or utility distribution or transmission system. This article will present basic transformer information that may help the reader appreciate how they operate and their many features.

Dissolved gas analysis for oil filled transformers

  • March 2012
  • Number of views: 6618
  • Article rating: No rating

The intent of this article is to provide an overview of the more common techniques used for dissolved gas analysis (DGA) of mineral oil. Types of gases created during transformer faults. There are several key gases produced during transformer faults. The type of gas and the quantity depends on the materials involved in the fault, the energy dissipated at the fault location and the solubility of the gases in oil.

Topics covered include:

  • Types of gases created during transformer faults
  • Methods of analysis and interpretation
  • Dornenburg ratios
  • Rogers ratios
  • Key gas method
  • Gas limits
  • Duval triangle
  • Analyzing other gases
  • Factors affecting gas concentrations and diagnosis

Aluminum-to-copper magnet wire winding conversions: Considerations for deciding whether wire area should be reduced

  • December 2011
  • Number of views: 13762
  • Article rating: 4.3

Although aluminum magnet wire theoretically can be converted to copper magnet wire of about 5/8 of the original wire area, in some cases this is not advisable. In others, it may result in a change in the magnetic strength of a coil or winding. In this article we will address the most common aluminum-to-copper magnet wire conversions as well as how to deal with whether the wire area should be reduced. Topics discussed include:

  • AC motor windings
  • Shunt fields
  • Series fields and interpoles
  • Transformer windings

Replacing aluminum conductors with copper conductors in power and distribution transformers up to 10 MVA

Design issues and differences in material properties must be considered before proceeding

  • August 2010
  • Number of views: 6700
  • Article rating: 2.5

There are many transformers in use rated up to 10 MVA (10,000 kVA) that were originally wound using aluminum conductors. When damaged or when selected for rewind, the aluminum conductor is often replaced with copper conductor. This is usually fairly routine when the conductor changes are undertaken within the bounds of the original transformer design. It is this type of change that will be reviewed in this article. It is not the intent to provide information here for the complete redesign of the transformer. It is important that all coil dimensions remain as close to the originals as possible. In carrying out the type of change outlined above, there are some design issues and differences in material properties that must be considered before proceeding with the work. Some of these issues are:

  • The effect that the difference in thermal characteristics of the materials will have on short term overload capability.
  • The effect that the different material properties will have on the original blocking and bracing system.
  • The effect that the difference in conductivity will have on conductor size.
  • The effect that the difference in conductor size may have on coil resistance and reactance.
  • The effect that the different conductor size may have on coil size (axial length) and hence its ability to withstand short circuits.

Getting The Most From Your Electric Motors

Getting The Most From Your Electric Motors - coverThis 40-page booklet provides great advice for obtaining the longest, most efficient and cost-effective operation from general and definite purpose electric motors.

This booklet covers topics such as:

  • Installation, startup and baseline information
  • Operational monitoring and maintenance
  • Motor and baseline installation data
  • How to read a motor nameplate
  • Motor storage recommendations



EASA/AEMT Rewind Study

EASA Rewind Study cover

The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors
Tests prove Premium Efficiency/IE3 Motors can be rewound without degrading efficiency.


ANSI/EASA AR100-2020

ANSI/EASA AR100-2015 cover

Recommended Practice for the Repair of Rotating Electrical Apparatus
This is a must-have guide to the repair of rotating electrical machines. Its purpose is to establish recommended practices in each step of the rotating electrical apparatus rewinding and rebuilding processes.



EASA Technical Manual

EASA Technical Manual cover

Revised September 2022
The EASA Technical Manual is the association's definitive and most complete publication. It's available FREE to members in an online format. Members can also download PDFs of the entire manual or individual sections.