Series Connected D.C Motor Characteristics

  • Thread starter Thread starter 1988ajk
  • Start date Start date
  • Tags Tags
    Motor Series
Click For Summary

Discussion Overview

The discussion focuses on the characteristics of series connected D.C. motors, specifically the nature of the speed/torque relationship. Participants explore whether this relationship is linear or follows a different pattern, considering both theoretical and practical aspects of motor behavior.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asks if the speed/torque relationship of a series connected D.C. motor is linear or curved, noting that speed decreases as torque increases.
  • Another participant suggests that the relationship is 'mostly' linear but acknowledges the presence of nonlinear artifacts in real motors.
  • A different viewpoint claims that the torque-speed curve is hyperbolic due to the series connection of the armature and field windings.
  • One participant provides additional context about the motor's characteristics, stating that the series field has low resistance, leading to quick saturation and resulting in high starting torque but poor speed regulation as load increases.
  • A later post questions whether a permanent magnet D.C. motor would exhibit the same characteristics, presuming that the behavior would be similar since magnets perform a comparable function to windings.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the speed/torque relationship, with some suggesting linearity and others asserting a hyperbolic shape. The discussion remains unresolved regarding the exact characteristics of series connected D.C. motors.

Contextual Notes

There are mentions of nonlinear artifacts and saturation effects, but the discussion does not resolve the implications of these factors on the overall behavior of the motor.

1988ajk
Messages
28
Reaction score
0
Hi all,

Please excuse me for such a simple question, I am a predominantly a mechanical engineer.

Does a series connected D.C Motor have a linear speed/torque relationship or a curve?

I am aware that both have speed (RPM) decreasing as torque (Nm) increases.

Many thanks in advance!
 
Engineering news on Phys.org
Many thanks,

the last post has cleared up some ambiguous notes I have.
 
Since your series field is in series with your armature, and has a very low resistance, about .4 ohms... it saturates very quickly providing maximum flux on relatively low provided current. For that reason, the motor has Amazing starting torque, but since the winding is saturated early it produces less and less torque as armature current is applied form no load to full load.

In summary, the motor has excellent torque on starting, but has poor speed regulation from no load to full load (as armature current is applied)
 
say if the d.c motor were a permanent magnet type, would this have the same characteristics?

I presume that they would stay the same, as the magnets do the same 'job' as windings.
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
Replies
3
Views
2K
Replies
5
Views
6K
Replies
9
Views
2K
Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 74 ·
3
Replies
74
Views
6K
  • · Replies 7 ·
Replies
7
Views
3K