DIYnot
Local | Network
   DIYnot > Forums
Local | Network
DIYnot Network Local DIYnot Network Local  
  Forum IndexForum Index     RulesRules    HelpHelp     Join FREERegister Free     About CookiesCookies     SearchSearch     LoginLogin 

star delta


 
Post new topic   Reply to topic    DIYnot.com Forum Index > Electrics UK
Search this topic :: View previous topic :: View next topic  
Author Message
markymark2406

from United Kingdom

Joined: 07 Mar 2007
Posts: 250
Location: Ipswich,
United Kingdom
Thanked: 1 time

PostPosted: Sat Sep 08, 2007 9:50 pm Reply with quote

whats the fifference between a star and delta motor and why?
Back to top
 Alert Moderators

If you do not want to see this advert, click here to login or if you are new click here to join free.
ricicle

from United Kingdom

Joined: 14 Sep 2006
Posts: 6298
Location: Gloucestershire,
United Kingdom
Thanked: 375 times

PostPosted: Sat Sep 08, 2007 10:14 pm Reply with quote

The subject of motors can be quite involved.Basically most 3 phase induction motors have 3 windings.In the majority of them these winding 'ends' are brought out into the terminal box.If you look at the rating plate it will tell you which configuration to use.Most will be designed to run at 415V in Delta, however this can lead to high start up currents due to the max. voltage being applied when the motor is stationary and there is no oppostion to current flow.This can be overcome by reducing the voltage across each winding by connecting them in Star.
However the disadvantage of this is that you have reduced the starting torque of the motor and may prove a problem in some applications.

If you can imagine the windings are called A, B and C.So winding A will have 2 ends A1 and A2 etc.Connection in Star means that A2, B2 and C2 are connected together and 3 phase is applied to A1, B1 and C1.
For Delta connection A1,C2 are together, as are A2, B1 and B2, C1.3 phase is applied to each of these pairs.
Older Star/delta starters were manual, but more recent ones are automatic, the changeover time between Star/Delta operation being determined by how the load reacts.

Hope this helps.
Back to top
 Alert Moderators
Space cat

from United Kingdom

Joined: 09 Sep 2007
Posts: 3861
Location: Newcastle upon Tyne,
United Kingdom
Thanked: 74 times

PostPosted: Sun Sep 09, 2007 4:15 pm Reply with quote

I find that a diagram saves a thousand words. The only trouble is that I don't know how to post diagrams here!

Delta is the fourth letter of the Greek alphabet and the upper case symbol is a triangle (but maybe you knew that already). Draw yourself a triangle with all sides equal and then put a dot right in the centre. Now draw three lines out from this dot to the triangle's vertices. That's the star. For a delta connected motor the windings are in the three sides of the triangle; for star connection they are in the three arms of the star.

This is more than just a wiring diagram because the lengths of those lines represent voltages and their angles are the phase angles. If each side of your triangle is 415 volts then the three arms of the star are, very nearly, 240 volts. You can check this using trigonometry or careful measurement on a scale diagram.

On a star connected three phase supply the centre dot is neutral but you don't need to make this connection on the motor because the currents in the three arms of the star add up to zero.
Back to top
 Alert Moderators
markymark2406

from United Kingdom

Joined: 07 Mar 2007
Posts: 250
Location: Ipswich,
United Kingdom
Thanked: 1 time

PostPosted: Sun Sep 09, 2007 4:55 pm Reply with quote

It would be good to see diagrams of these, any chance?
Back to top
 Alert Moderators
davy_owen_88

from United Kingdom

Joined: 17 Nov 2006
Posts: 1680
Location: West Glamorgan,
United Kingdom
Thanked: 1 time

PostPosted: Sun Sep 09, 2007 5:35 pm Reply with quote

Space cat, have a look through this thread for information on how to upload and insert a picture into your post.

If the image is already uploaded then you just have to copy the address for the image and put IMG tags around it like this:

[img]blahblahblah[/img]
Back to top
 Alert Moderators
Space cat

from United Kingdom

Joined: 09 Sep 2007
Posts: 3861
Location: Newcastle upon Tyne,
United Kingdom
Thanked: 74 times

PostPosted: Sun Sep 09, 2007 11:00 pm Reply with quote

Thanks davy. I'll study that next time I'm properly awake.
Back to top
 Alert Moderators
Spark123

from United Kingdom

Joined: 02 Jun 2005
Posts: 14198
Location: Cumbria,
United Kingdom
Thanked: 400 times

PostPosted: Sun Sep 09, 2007 11:36 pm Reply with quote

Back to top
 Alert Moderators
empip

from United States Minor Outlying Islands

Joined: 24 Sep 2005
Posts: 5377
Location: United States Minor Outlying Islands
Thanked: 47 times

PostPosted: Mon Sep 10, 2007 7:22 am Reply with quote

Back to top
 Alert Moderators
markymark2406

from United Kingdom

Joined: 07 Mar 2007
Posts: 250
Location: Ipswich,
United Kingdom
Thanked: 1 time

PostPosted: Thu Sep 20, 2007 7:54 pm Reply with quote

Just confirm someone the links you put in the connection box on the motor? in star i know that you linkout one side UVW but what about delta?
Back to top
 Alert Moderators
ricicle

from United Kingdom

Joined: 14 Sep 2006
Posts: 6298
Location: Gloucestershire,
United Kingdom
Thanked: 375 times

PostPosted: Thu Sep 20, 2007 8:01 pm Reply with quote

markymark2406 wrote:
Just confirm someone the links you put in the connection box on the motor? in star i know that you linkout one side UVW but what about delta?


U1-W2, U2-V1, V2-W1
Back to top
 Alert Moderators
markymark2406

from United Kingdom

Joined: 07 Mar 2007
Posts: 250
Location: Ipswich,
United Kingdom
Thanked: 1 time

PostPosted: Thu Sep 20, 2007 8:08 pm Reply with quote

still not clear, can you draw or direct me to a website with pictures?
Back to top
 Alert Moderators
ricicle

from United Kingdom

Joined: 14 Sep 2006
Posts: 6298
Location: Gloucestershire,
United Kingdom
Thanked: 375 times

PostPosted: Thu Sep 20, 2007 8:47 pm Reply with quote

Have you checked on the inside of the terminal box cover - there is usually a diagram in there?

There should be 6 studs - U1 U2, V1, V2, W1, W2

It should be possible to fit a link between U1+W2, a link between U2+V1 and a link between V2+W1.

This normally creates 3 parallel links.You then wire ONE incoming phase to each of these links.

If you still don't understand I suggest you read up before you undertake this kind of work. icon_wink.gif


Last edited by ricicle on Fri Sep 21, 2007 5:47 pm, edited 1 time in total
Back to top
 Alert Moderators
Spark123

from United Kingdom

Joined: 02 Jun 2005
Posts: 14198
Location: Cumbria,
United Kingdom
Thanked: 400 times

PostPosted: Fri Sep 21, 2007 7:25 am Reply with quote

Back to top
 Alert Moderators
Search this topic :: View previous topic :: View next topic  
Post new topic   Reply to topic    DIYnot.com Forum Index > Electrics UK All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Similar Topics   Replies   Views   Posted 
Star Delta 10 240 Thu Mar 20, 2014 10:54 pm
Remote controlling star delta starter 37 4940 Sun Dec 12, 2010 9:37 pm
star/delta line current formulas 2 660 Sat Nov 22, 2003 2:06 am
MEM DELTA switches 4 640 Wed Apr 22, 2009 7:13 pm
star ceiling kits - fibre optic lighting 9 900 Mon Jun 15, 2009 10:31 am


 
DIYnot
Find an Expert | Find a Supplier | Search DIYnot.com
Network | Advertising | Newsletter
DIY | DIY How To | @home | DIY Wiki | DIY Forum
By using this site you agree to our Terms of Service / Disclaimer.
Please read our Privacy Policy. Copyright © 2000-2014 DIYnot Limited.