All About Circuits Forum Pros & Cons of Wye vs. Delta motor windings.
 Register Blogs FAQ Members List Today's Posts Search Today's Posts Mark Forums Read

 General Electronics Chat Discussion forum for general chat about anything electronics related, including asking questions about material in the All About Circuits E-book, Worksheets, and Videos.

#1
01-02-2012, 02:00 PM
 Blue-Photon New Member Join Date: Jan 2012 Posts: 4
Pros & Cons of Wye vs. Delta motor windings.

What are the advantages / disadvantages of connecting a 3Phase motor in Delta vs. Wye?

(I have been searching for answers to this question for some time. All forums I've visited gave only half baked answers, so I'm hoping this one will be a little more professional.)

I have a small (0.75HP) 6 wire motor - currently connected as Y with center floating. The name plate states: Y/Δ, 230/380 VAC, which tells me I can configure it both ways. If possible I'd like to get more power out of it, so the question is will a Delta connection achieve this?

Many people have stated that there is no power (or other) advantage or disadvantage between the two connections, but if that is the case, why would so many (larger) motors use Wye-Delta starters? These motors clearly "kick-in" when they switch from Y to Δ. If there is no advantage, then why aren't all motors simple connected in Y, and left that way (Y/Δ starters are much more complex and expensive)?

Blue-Photon
#2
01-02-2012, 02:38 PM
 strantor Senior Member Join Date: Oct 2010 Location: Houston tx Posts: 3,581

Your motor is meant to be connected Δ 230 or Y 380. When you connect Δ, you get full applied voltage across each winding. in Y, you get a voltage divider effect across 2 windings at a time. wye-delta starters are a "soft start" or "reduced voltage start" - they start out in wye, giving less voltage across each winding, and then switch to delta.

#3
01-02-2012, 02:50 PM
 jimkeith Senior Member Join Date: Oct 2011 Location: Pennsylvania Posts: 538

There is no power output advantage when connected Δ.
#4
01-02-2012, 02:58 PM
 Blue-Photon New Member Join Date: Jan 2012 Posts: 4

Hi Strantor,

Thanks for your quick answer. I fully realize and understand what you have stated, but this dosen't quite answer my question.

I understand that Vpp in Y = Vpp in Δ, and in Wye Vpn = Vpp/√3, so the voltage from phase to neutral is reduced by √3.

If what you have said is correct (that this motor is designed for Y380 and Δ230), then connecting in Delta 380 would definately increase the power, but it could also run hot and fry the windings. To my knowledge however there is no Δ230 (readily) available in Europe. We only have Y380 phase to phase (230 phase to neutral), and Δ380.

Blue-Photon

Last edited by Blue-Photon; 01-02-2012 at 03:28 PM. Reason: Correction
#5
01-02-2012, 03:15 PM
 jimkeith Senior Member Join Date: Oct 2011 Location: Pennsylvania Posts: 538

The winding current is unchanged in either connection--the phase current does change by the √3 factor.

#6
01-02-2012, 03:25 PM
 GetDeviceInfo Senior Member Join Date: Jun 2009 Location: Canada Posts: 1,501

your question on wye/delta start has more to do with the nature of the load. The motor just converts electrical energy to mechanical energy. Considering Stantors comments, with a Delta configuration you'll have full torque applied instantaneously to the load. If the load has high inertia, this can be very hard on transmission components, and will result in extended starting currents on the motor, causing high heat generation. Motor overload devices are placed inline to protect motors from extended current draws and when properly sized, will prevent such starts. With the Wye connection and the subsequent reduction of voltage on the windings, your available horsepower is cut to 1/3 rating. This greatly reduces the strain on the drive on start up. Once the drive is up to some speed, it is switched over to Delta to obtain full rated HP.

Not all loads are of this nature. In fact most loads in industry can be started without HP reduction. Electronic softstarters are now being integrated with power contactors and the costs are giving them wider usage. I've seen Wye/Delta starters applied to drives down to 1 Hp.

The other concept is as Stantor mentioned. By reconnecting your windings, you have an option of source voltages that you can connect to. Some of the most useful motors in industry are dual voltage motors. These are not Wye/Delta, but the optional voltage is immensly usefull.

Quote:
 I have a small (0.75HP) 6 wire motor - currently connected as Y with center floating. The name plate states: Y/Δ, 230/380 VAC, which tells me I can configure it both ways. If possible I'd like to get more power out of it, so the question is will a Delta connection achieve this?
Yes, but you cannot exceed your current ratings, so again it's more of a question, can you drive a bigger load? Yes, within the ratings of the motor.

With all that being said, you should probably give us full nameplate data, as you may have a multispeed motor.
__________________
I get all the news I need on the weather report

Last edited by GetDeviceInfo; 01-02-2012 at 03:34 PM.
 The Following 2 Users Say Thank You to GetDeviceInfo For This Useful Post: Blue-Photon (01-02-2012), bug13 (11-20-2012)
#7
01-02-2012, 03:47 PM
 Blue-Photon New Member Join Date: Jan 2012 Posts: 4

Quote:
 Originally Posted by GetDeviceInfo your question on wye/delta start has more to do with the nature of the load. ... Yes (you will get more power), but you cannot exceed your current ratings, so again it's more of a question, can you drive a bigger load? Yes, within the ratings of the motor.
So if I understood correctly:

If I connect this motor in Δ(380) I will theoretically increase the possible power output.

If however in Y connection it is already reaching its maximum power rating, pushing it to Δ to deliver more power could (will) cause it to overheat.

This makes more sense to me.
#8
01-02-2012, 04:28 PM
 strantor Senior Member Join Date: Oct 2010 Location: Houston tx Posts: 3,581

Quote:
 Originally Posted by Blue-Photon So if I understood correctly: If I connect this motor in Δ(380) I will theoretically increase the possible power output. If however in Y connection it is already reaching its maximum power rating, pushing it to Δ to deliver more power could (will) cause it to overheat. This makes more sense to me.
yes. you could theoretically wire it in delta at 380V but you would have to derate it.
 The Following User Says Thank You to strantor For This Useful Post: Blue-Photon (01-03-2012)
#9
01-03-2012, 08:09 AM
 Blue-Photon New Member Join Date: Jan 2012 Posts: 4

Things are much clearer for me now. It's nice to clear out a few cobwebs, since my EE courses date back 30+ years (I'm mechanical not electrical, but don't hold it against me).

Cheers, and happy new year!

Blue Photon

___________

Fear of the Lord is the beginning of wisdom. Pr. 1:7
#10
01-03-2012, 11:09 AM
 jimkeith Senior Member Join Date: Oct 2011 Location: Pennsylvania Posts: 538

Quote:
 Originally Posted by strantor yes. you could theoretically wire it in delta at 380V but you would have to derate it.
This will saturate the magnetics and probably will not provide significant additional torque. In saturation, the current will dramatically increase and overheat the motor. You must derate the voltage in this case--back to 230VAC.
 The Following 2 Users Say Thank You to jimkeith For This Useful Post: bug13 (11-20-2012), strantor (01-03-2012)

 Tags cons, delta, motor, pros, windings, wye, wye vs. delta connection, wye-delta motor

 Related Site Pages Section Title Worksheet Delta and Wye 3-phase circuits Worksheet AC motor control circuits Worksheet Polyphase power systems Worksheet Autotransformers Worksheet DC motor control circuits Textbook Three-phase Y and Delta configurations : Polyphase Ac Circuits Textbook Three-phase transformer circuits : Polyphase Ac Circuits Textbook Harmonics in polyphase power systems : Polyphase Ac Circuits Textbook Rectifier circuits : Diodes And Rectifiers Textbook -Y and Y- conversions : Dc Network Analysis

 Similar Threads Thread Thread Starter Forum Replies Last Post jegues Homework Help 1 10-13-2011 06:31 AM scriverman General Electronics Chat 4 03-29-2011 02:50 AM Student01 Homework Help 5 03-08-2010 02:01 AM filemod Homework Help 4 06-23-2009 03:55 PM manish oberoi General Electronics Chat 2 07-16-2008 05:48 AM

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Electronics Forums     General Electronics Chat     The Projects Forum     Homework Help     Electronics Resources Software, Microcomputing, and Communications Forums     Programmer's Corner     Embedded Systems and Microcontrollers     Computing and Networks     Radio and Communications Circuits and Projects     The Completed Projects Collection Abstract Forums     Math     Physics     General Science All About Circuits Commmunity Forums     Off-Topic     The Flea Market     Feedback and Suggestions

All times are GMT. The time now is 03:37 AM.