- Occupation
- Licensed Electrician
Just having a little fun on a cold and windy day.
Star delta connection of induction motor
- Thread starter panthripu
- Start date
- Status
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Regardless of what everyone THINKS it is, the fact remains that IF it was designed as Star or Delta connections, one of those is not going to be right. So most likely is it SUPPOSED to be connected in Star and when connected in Delta, that would have been for a lower voltage, so by applying the higher voltage, you are saturating the windings and making them into 60A heater cores. Stop doing that...
My theory: it's actually an IEC motor designed for 230/400V 50 Hz to where it is 400V if connected in Star and 230V if connected in Delta. Then because 400V 50Hz is pretty close to the same V/Hz ratio as 460V 60Hz (8:1 vs 7.7:1, so well within 10%), the motor was labeled as 460V 60Hz, but NOT as 230V 60Hz, because the V/Hz ratio would be out of tolerance (4.6 vs 3.83, so 17% difference). So to use it at 460V you had to connect in Star, then for that motor, there was NO VALID USE in Delta. That is what I think you have discovered by trial and error here.
My theory: it's actually an IEC motor designed for 230/400V 50 Hz to where it is 400V if connected in Star and 230V if connected in Delta. Then because 400V 50Hz is pretty close to the same V/Hz ratio as 460V 60Hz (8:1 vs 7.7:1, so well within 10%), the motor was labeled as 460V 60Hz, but NOT as 230V 60Hz, because the V/Hz ratio would be out of tolerance (4.6 vs 3.83, so 17% difference). So to use it at 460V you had to connect in Star, then for that motor, there was NO VALID USE in Delta. That is what I think you have discovered by trial and error here.
- Occupation
- Licensed Electrician
You're late to the party, stop trying to cut in line.
iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
- Occupation
- EE (Field - as little design as possible)
That part is absolutely true
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But
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jr did bring up a scenario that is possible. Somewhat more convoluted than any I thought of - but that is okay. This thread is about, "How many wild, unverifiable scenarios are there?" .................................. Lots
Here is my translation (jr - I'm open to correction if I missed)
Motor is originally an IEC, 50 HZ, 400V wye or 230V Delta.
This is a 6 lead motor, which would explain the ability to connect Y or D.
Motor relabeled as a 460V, 60 HZ, connected as a wye.
At 60 HZ, each coil is 230 X (6/5) = 276 V (that keeps the V/HZ right).
Assuming a nominal 7.5 HP motor:
If one did connect delta to 230V, the horsepower drops to 69% = 5.2 HP
If one were to connect the 276V delta connection to 480V, motor would saturate, giving extremely high unloaded currents.
So, it works - at least as well as some of mine
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
So just generally speaking, Is there something specific about a wye start delta run motor, besides of course the leads to make the change being physically available and being normally connected delta? My understanding was it is really the controller that is "wye start delta run". I just did a quick dirty search and looked at some catalogs and I could not find any "wye start delta run" motors. Nor could I find any mention of the number of leads or the winding configuration.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Sounds to me like the motor is operating exactly as expected. It is made to be used wye connected. When used in this fashion the no load current is about right compared to the rated full load current.
This motor simply should _not_ be operated connected to 460V 60Hz in delta.
-Jon
- Occupation
- Licensed Electrician
Size of the motor and what it's driving. It's basically a way to soft start a motor. Big pumps and big fans is what I have seen them on.
ptonsparky
Tom
- Occupation
- EC - retired
One of the mfg plants in the area had moved a machine from one building to another and lost track of the connections. For whatever reason they called us in to fix it. Once I understood what they wanted CH had a diagram in their catalog. Note to beginners: Those catalogs are full of good info.
The only other instance I've seen was an option for it on a SoftStart.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Thanks but that didnt answer my question. I know its a reduced voltage starting method for large motors. I want my money back.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
As mentioned earlier it is also how most IEC dual voltage motors change voltage - connect in wye configuration for 416 volts input or connect in delta configuration for 240 volts input. They are usually 50 Hz rated motors as well, but 480 volts @ 60 Hz is close enough in V/F ratio that it can work.Thanks but that didnt answer my question. I know its a reduced voltage starting method for large motors. I want my money back.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
So then one of these IEC dual voltage motors could be used on a 240V system with a WS-DR controller if needed/desired?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Maybe so, but frequency needs consideration. They are usually only going to work (and last) on 50 HZ @ 240 volts
We don't normally have three phase 240V. That's usually a single phase supply and nominally 230V.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I know you don't, but there must be some place those dual volt motors are being used at 230-240 volts.
- Occupation
- Licensed Electrician
Let's try this then. You need a motor that has six or twelve leads to do a wye start delta run at the appropriate voltage. A nine lead IEC motor is only going to use wye or delta for a dual voltage, 480 or 240V respectively.Thanks but that didnt answer my question. I know its a reduced voltage starting method for large motors. I want my money back.
Does it mean that the motor has to be run in the configuration given in name plate ( either Y or delta) ? What about some of the motor have many options like one of them I have come across.
50Hz , 400V/690V-Delta/Wye , 5kW,100.6A/6.1A,1460 rpm
50Hz ,380-420V/660-725V Delta/Wye , 10.6-11.1A/6.1-6.4A
60Hz,460V delta , 5.8kW , 10.3A,1760 rpm
These all informations are given on same motor.
Does it mean that this motor can be run in delta when operated with 400 to 460 V and Wye when operated with 690V ?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Yup. In each case, the motor windings will "see" the same voltage.
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