The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
Today at 04:24 PM
On Delay Relay with Auto Reset
by Potseal
Yesterday at 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 15
HotLine1 10
Texas_Ranger 8
Trumpy 8
sparkyinak 7
Who's Online
0 registered (), 218 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#7453 - 02/06/02 04:56 AM Three Phase Motors
Frank Cinker Offline
Member

Registered: 07/29/01
Posts: 317
Loc: Pennsylvania
In general, what are the advantages of a three phase motor over a single phase motor.
I believe three phase motors run more efficient and have a longer life expectancy among other advantages.

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#7454 - 02/06/02 05:29 AM Re: Three Phase Motors
ctolbert Offline
Member

Registered: 08/09/01
Posts: 33
Loc: Cumming, GA USA
Frank:

Check this out:
http://www.motorsanddrives.com/cowern/contents.html

The cowern papers are pretty handy for these kind of comparisons. Being more efficient and longer lasting are true, but also look at direction of rotation, size in HP, and versitility.

Carl

[This message has been edited by ctolbert (edited 02-06-2002).]
_________________________
Carl Lee Tolbert
Technical Support
AC Drives
Automationdirect.com
Your source for the most practical automation products at almost-free pricing, delivered by 11 a.m., just by clicking a mouse.
PH: (770)844-4200
Fax:(770)886-3199
http://www.automationdirect.com

Top
#7455 - 02/06/02 05:31 AM Re: Three Phase Motors
Joe Carpenter Offline
Member

Registered: 12/19/01
Posts: 55
Loc: USA
A few advantages for us is, Faster startup which means a lower startup cost. Lower initial cost of motor. They have less components, (capacitors, centrifigal switches)therefore less to go wrong.
If you have 480v service and use 3phase 460v motors, they do not have to go thru your own transformers thereby eliminating unnecessary load an transformers.
I know there are more. these are just a few of the benefits we see in our plant.

Top
#7456 - 02/06/02 08:18 PM Re: Three Phase Motors
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
Polyphase motors are self starting and they may have a lower level of Reactive / shuttle power bouncing between the windings and the transformer.
Also, they require a lower FLA than their 1 phase counter parts.

All that stuff makes them have better overall efficiency for all areas concerned.

Other than this stuff, the HP [or wattage consumed] is equal on 1 phase motors and polyphase motors.

Oh ya, since they are self starting, they don't need the annoying aux/start circuit [or other starting means], and do not create double frequency pulsations on the shaft [or reflected back to the system in harmonic distortions].

Drawbacks:
  • Require Polyphase AC Systems,
  • Loss of one phase will create problems


Scott SET
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals