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
Forum Software Upgrade coming soon...
by Webmaster
9 minutes 34 seconds ago
Faricating Guards out if Lexan?
by frank
Today at 04:33 PM
Would ELV branch circuits be a good idea?
by LongRunner
Today at 07:42 AM
100% breakers?
by Texas_Ranger
Today at 06:13 AM
Dangerous DIY Advice
by Potseal
01/12/17 09:52 AM
New in the Gallery:
Desk-mounted "power-board"
Shout Box

Top Posters (30 Days)
HotLine1 15
gfretwell 11
Webmaster 11
ghost307 10
Trumpy 9
Who's Online
2 registered (sparkyinak, Webmaster), 110 Guests and 5 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#47873 - 01/27/05 11:03 PM 2pole but 3 phase
Edward Offline
Member

Registered: 12/14/02
Posts: 309
Loc: California
i saw a wood working machinary that had 4 MOTORS on it. On the name plate of each motor it was STAMPED 2 POLE however on the body of the motor it clearly said 3 phase iduction motor. And it had 3 leads going to the motor housing.
My question is what does that 2pole refer to?

Number of phases? I dont think so.

Number of poles inside???????

Thanks
edward
_________________________
Thanks
Edward

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....

#47874 - 01/28/05 03:16 AM Re: 2pole but 3 phase
oldtimer Offline
Junior Member

Registered: 07/26/02
Posts: 7
Loc: raymond, ohio, u.s.a.
the number of poles relates to a motor's r.p.m. 2 poles = 3600 r.p.m.
4 poles = 1800 r.p.m.
6 poles = 1200 r.p.m.
(nominal speeds with no slippage factored in)

this has to do with the number of windings in the stator and how their grouped, not whether their single-phase or three-phase.

Top
#47875 - 01/28/05 05:35 AM Re: 2pole but 3 phase
winnie Offline
Member

Registered: 09/15/03
Posts: 652
Loc: boston, ma
In particular, the number of 'poles' describes the shape of the magnetic field produced inside the motor.

In a conventional induction motor, magnetic flux threads across the 'airgap', the space between the rotor and the stator. Just like a conventional bar magnet, some parts of the stator will be north poles, and some parts will be south poles. In operation, the position of the poles rotates.

The magnetic field will rotate by one pair of poles per AC cycle. So when you feed 60Hz AC into a 2 pole motor, the magnetic field will rotate 60 times per second, or 3600 RPM. If you feed 60Hz AC into a 4 pole motor, the magnetic field only rotates half a turn per AC cycle, or 30 times per second, or 1800 RPM

-Jon

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