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DC motor applications: Types of fields and benefits of each

  • April 2018
  • Number of views: 1963
  • Article rating: 5.0

For the wide variety of DC motor applications, there are those where a straight shunt motor is preferred and others which seem to require the greater starting torque of a series field. Why are there different field designs and are they interchangeable? What about the nameplates marked “stab shunt” or “str shunt?” The purpose of this article is to clear up lingering confusion about the types of fields as well as the benefits of each.

Aplicaciones de motores de CC: Tipos de campos y beneficios de cada uno

  • April 2018
  • Number of views: 1440
  • Article rating: No rating

Para la amplia variedad de aplicaciones de motores de CC, existen aquellas en las que se prefiere un motor shunt directo (straight shunt) y otras que parece que necesitan el mayor torque de arranque de un campo serie. ¿Por qué existen diferentes diseños de campo y son intercambiables? ¿Qué sucede con las placas de datos marcadas como “stab shunt” o “str shunt?” El propósito de este artículo es aclarar la confusión permanente sobre los tipos de campos, como también los beneficios de cada uno.

Considerations when working with compound wound DC fields

  • December 2014
  • Number of views: 2310
  • Article rating: No rating

Occasionally a customer wants a spare DC machine, and you find a replacement that is almost – but not quite – identical. Often, either the original or the spare is compound wound. The customer then asks: “What do the series fields do?” and “Can we just isolate the series leads?”  There are a couple of considerations, but the answer is that “it depends.”

Follow these procedures to reduce problems when rewinding field coils

  • April 2008
  • Number of views: 2259
  • Article rating: 4.3

When rewinding field coils, there are a couple of common problems that make life difficult for the service center. One problem occurs when the newly rewound set of shunt fields is returned to the service center, roasted again. What causes this, and whether we can improve our winding procedure, has been the subject of much discussion. We all realize that something caused that first failure. If the subsequent failure looks a lot like it - the shunt fields were charred in both cases then it seems logical that the underlying cause could be the same. Sometimes it is. Let's look at why the coil is burnt. Well sure, it got too hot. But why? Is it because the shunts are energized when the machine is otherwise shut down? If so, the fields can be automatically de-energized after "x" minutes of machine inactivity. Installing a timed relay in the controls will avoid future problems. It may be that the customer is able to trace the problem to a new operator, who needs more training.

Trickle heating is a practical option to prevent condensation

  • April 2006
  • Number of views: 3661
  • Article rating: 5.0

Trickle heating is another very practical option to heat AC stator windings or DC field windings while they are not energized.

Training Film 19: Layer-Winding DC Field Coils

  • June 1985
  • Number of views: 1747
  • Article rating: No rating

Covers all necessary steps for layer-winding DC field coils, how to layer-wind a shunt field coil, how to reinsulate an interpole field coil, and how to install large field coils in the frame.

Training Film 18: Random-Winding DC Field Coils

  • June 1984
  • Number of views: 1678
  • Article rating: No rating

Illustrates procedures for manufacturing random-wound interpole and main field coils for DC machines. Covers everything from removing old coils and taking data to installing and connecting new coils, including how to construct winding forms and jigs, how to shape coils to conform with the curvature of the field frame and how to insulate field coils. Both “wet” and “dry” winding techniques are illustrated.

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 May 2021
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.