Operating 266V Motors on 230V..... Explain Please

[Peter Hurley]

I know this is an electronics forum and not an electrical forum. But it is the only electric forum I belong to and trust. Sooooo......

I have an opportunity to purchase some nice 3hp Sew Eurodrive Gearmotors at a great price. They are 266v/460v rated motors which I would operate on 230v. I have run across this before and typically pass as there are other options. BUT, ignorance is not a good trait. So I sat down and decided to search for the 266v vs 230v detail explanation. There are NONE........

Who here truly understands the what and why of 266 motors in the US anyway. They do not meet the 10% deviation (Sew holds their formal installations directives to 5%)........ 230v x 1.1 = 253v. AND I find it hard to believe ANY company would accept the cost of HAVING to install transformers for such a motor usage. Just buy a 230v. SEW produces great products...... and I suspect that if the derated HP is acceptable, it would be fine to install a 266v on 230v system???!!!???!!! But my ignorance is unacceptable on my end.

Your help will be greatly appreciated.
Thanks
Pete

 

[BobK]

That is a 3-phase motor. It will not run from a US 230V line, which is single phase.

Bob

 

[Peter Hurley]

I operate on Three Phase electric and this installation will be for three phase.

 

[Minder]

Where is the US do you have 230v 3ph, You may get away with running them at the lower voltage but with lower performance.
BTW, 266v results from one phase to neutral on a 3ph 460v star secondary, but that will not help with a 3ph transformer.
M.

 

[Tha fios agaibh]

I wouldn't run them at 230v other than briefly with minimal loads. Besides lowered performance, the internal cooling will be inadequate and shorten its life.
Best to just buy a frequency drive (VFD) to drive it.
Another consideration is the voltage tolerance of the internal brake rectifier that normally is fed with 266vac (tied to winding) and sends 120vdc to release brake. Would the rectifier be ok with 230? Idk offhand.

 

[Peter Hurley]

Where is the US do you have 230v 3ph, You may get away with running them at the lower voltage but with lower performance.
BTW, 266v results from one phase to neutral on a 3ph 460v star secondary, but that will not help with a 3ph transformer.
M.

230v is the label of the motor after taking into consideration voltage drop. The fact of the matter is that I have three phase and I am trying to understand what 266v motors (actually a fair number of them) are doing operating in the US. It befuddles me to think ANY company would spend the money on transformers, etc.... to operate these motors when they simply can purchase the more common 230v to begin with.

So.... with the statement..... "266v results from one phase to neutral on a 3ph 460v star secondary"..... I can understand that maybe this motor's low voltage connection is a sort of single phase connection to a 460v supply?????

 

[Peter Hurley]

I wouldn't run them at 230v other than briefly with minimal loads. Besides lowered performance, the internal cooling will be inadequate and shorten its life.
Best to just buy a frequency drive (VFD) to drive it.
Another consideration is the voltage tolerance of the internal brake rectifier that normally is fed with 266vac (tied to winding) and sends 120vdc to release brake. Would the rectifier be ok with 230? Idk offhand.

I have been thinking the same. I have posted this question elsewhere and some say it will burn up... others say it will run and do so fine with lower torque though. If this were simply a lower torque situation, that can easily be worked into the design needs. In my case, the brake on these motors will not be needed. But I also was wondering about the brake and its electrical needs. It would be interesting to know.

 

[Minder]

All you would need to do is run for a period of time and monitor any temp rise.
As to the brake, normally this is a brake ON with no power, IOW it requires brake power to run, if these are of this type, then 120v 1 phase should be easily available, does't mention AC or DC though? Probably the former.
M.

 

[Peter Hurley]

The brake is of little issue. I am seeking the answer to the base question at hand. The brakes on SEW motors can be locked out manually and I suspect they are all built this way. And again, getting 120 to power the brake is doable too.

All you would need to do is run for a period of time and monitor any temp rise.
As to the brake, normally this is a brake ON with no power, IOW it requires brake power to run, if these are of this type, then 120v 1 phase should be easily available, does't mention AC or DC though? Probably the former.
M.

 

[JWHassler]

That motor may run with no problems on 277/480V, 60Hz

 

[Minder]

What does the hook up information say as to the two voltage methods, presumably you have the documented difference?
M.

 

[Peter Hurley]

I have yet to buy these motors and SEW keeps their installation info on the inside of the electrical box cover. Although I did look up the "R13" connection info..... and it was of no value in regards to answering this question.

 

[Peter Hurley]

That motor may run with no problems on 277/480V, 60Hz

That is what I am starting to think. I bet the 266 labeling represents the 4% line drop of a 480v single phase installation.......... aka 277v. 277 x .96 = 265.92 (266)

 

[Minder]

Were it me I would fire off a question (or two) to SEW http://www.seweurodrive.com/s_contact_us/contact_us.php5
Nothing to lose!
M.

 

[Peter Hurley]

Being a businessman myself and doing the CYA thing all the time....... SEW will give a 100% CYA answer. I am looking for real world applications and potential deviations. You get the gist. Thanks for taking the time to look it up.

Were it me I would fire off a question (or two) to SEW http://www.seweurodrive.com/s_contact_us/contact_us.php5
Nothing to lose!
M.

 

[Minder]

I have contacted manuf and service reps over the years and on the whole have had very useful responses or leads.
Your OP does not appear to be out of the realm of the extraordinary, often talking to someone in a technical position can reveal the odd nugget.
For the cost of it, it is worth typing a couple of words IMO.
It is often the luck of talking to the right person!
That's Just me!.
M.

 

[Tha fios agaibh]

That is what I am starting to think. I bet the 266 labeling represents the 4% line drop of a 480v single phase installation.......... aka 277v. 277 x .96 = 265.92 (266)

This is a three phase motor designed to have the windings wired either 460v wye, or 266v delta configuration. There is no single phase, but internally each winding will see 266v. 460/1.732(sqrt of 3)=266v
But I agree, it could be ran at 480 3ph which is only 4.5% over voltage.
Better to run motors slightly overvoltage than undervoltage.
Like I said the brake voltage is 120vDC fed from internal rectifier.
If you don't need it, disconnect the resistor wires and mechanically disengage it.

 

[Peter Hurley]

As Minder suggested..... I wrote Sew Eurodrive and received an answer from a "Mechanical Engineering Technician" out of South Carolina.

He would not give me any details in regards to what/why 266v but he made it abundantly clear I could hook the 266v to my 230v 3PH with no issues whatsoever. He simply stated that I will not get all 3 HP from the unit nor will it operate at its peak efficiency but it's full acceptable to install it as I requested.

I replied asking if these motors were originally designed to operate in some fashion from the 1PH of a 3PH 480v system and he replied with an absolutely not. A single phase motor is a single phase and a three phase a three phase.

Thanks for the help,
Pete