Three-phase Motor “Rules of Thumb” - Private Webinars - EASA | The Electro•Mechanical Authority
Facebook Twitter LinkedIn YouTube Menu Search Arrow Right Arrow Left Arrow Down Arrow Up Home Arrow Next Arrow Previous RSS Icon Calendar Icon Warning Icon

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.

Article

Three-phase Motor “Rules of Thumb”

  • October 2025
  • Number of views: 271
  • Article rating:

Tom Bishop, PE
EASA Senior Technical Support Specialist 

Often when we are dealing with three-phase squirrel cage motors we ask ourselves “Is there a standard or a rule of thumb for this motor characteristic?” The 10 characteristics that follow apply to conditions associated with motor starting as well as steady state operation. Examples are provided for each of the characteristics. Where applicable, the source NEMA or IEC standard clauses are cited in Table 1.

Table 1: Motor Characteristics with NEMA and IEC References
Topic NEMA MG 00001 IEC 60034-1
1. Voltage variation 12.44 & 20.14 7.3
2. Voltage unbalance 12.45, 12.36.2 & 20.24 none
3. Current variation 12.47 none
4. Current unbalance 14.36.5 none
5. Full load current 12.47 none
6. Locked rotor current 10.37.2 *
7. Instantaneous current at starting 12.36 none
8. Locked rotor stall time 12.49 none
9. Number of starts 12.54 & 20.12 none
10. Slip (synchronous rpm – rated rpm) 12.46 12.1
*IEC 60034-12 provides values for locked rotor apparent power.

 

AVAILABLE IN SPANISH

Available Downloads



Tags:
0Upvote 0Downvote
Print