460/60HZ to 360V/60HZ

[place1234]

How to convert a 3p/2HP/460v/60hz motor in applicaion 3p/2hp/360/60hz?
Motor needs rewind, is it?How to calculate the rewind date based on the original winding data?

 

[davidbeach]

Why not just put a 360 - 480V transformer ahead of the motor?

 

[MotoDrv]

Use a drive. Most drives have a fairly wide voltage range (380-460V some rated to full 480V) with a typical +/- 10% some are even at -15% V based on the low side of the voltage range. Both WEG and GE offer drives capable of 380-480V at +10% and -15%. The WEG is a CFW08 model and the GE (actually GE Fuji) is the AF-300 E11. I have used both and they are easy to program and very reliable. Also remember you get the motor protection and control out of the drive for probably less money and certainly less time than trying to re-invent the existing motor.

 

[davidbeach]

MotoDrv, could a drive really put out 460-480V given an input of 360V? A drive could be a great solution going the other direction to feed a 360V motor from a 480V source.

 

[waross]

I agree with David. I would use two 1 KVA transformers with 240 volt primaries and 2 x 120 volt secondary windings.
Connect them as open delta, auto transformer boost configuration. They will take 360 volts (240+120=360) up to 480 volts (240+120=120=480) and supply 4 amps. Your 2 hp motor should draw only a little more than 2 amps at 480 volts.
The transformers may be mounted at the motor location or the starter location, whichever is more convenient.
respectfully

 

[stardelta]

From the way I read it Places`s motor already requires a rewind for whatever reason. If cost is a factor surely it makes sense just to rewind it for the new voltage rather than rewind it for the original voltage then add extra costs and complicate the issue by adding Drives or Transformers.
Converting the winding for 360v operation is routine and straightforward for a competent shop. The original winding will have to be detailed and changes made to the wire cross-sectional area and number of turns per slot. For a drop in voltage it means less turns and an increase in wire CSA. The exact changes are arived at by means of a formula that all EASA member repair shops have access to. Note that full-load current will increase slightly after the conversion.

 

[ScottyUK]

Hi David,

Drives with an active front end to provide power factor correction use a form of boost converter to develop a high DC bus voltage even from a relatively low AC input while still drawing a fairly good representation of a sinusoidal current from the utility. These drives can operate in the manner described, with a higher output voltage than the input.


----------------------------------

Sometimes I only open my mouth to swap feet...

 

[davidbeach]

OK, thanks Scotty.

 

[jraef]

Yes Scotty, but neither of the drives mentioned by MotoDrv are that type, and unless the active front end is providing some other indispensable benefit, that would be far more expensive than a transformer, especially for a 2HP motor. Methinks you were just saying that for our general edification.

I also think MotoDrv just read the application information backwards. We've all made minor errors like that, at least I have

place1234,
Where are you seeing a 360V 60Hz power supply? I don't show that on any of my charts for world industrial voltages.

Another option, if you do not already have the motor, is to find a 2HP 1 phase 208V 60Hz rated motor, because the Y voltage of 360V is 208 (assuming you have a 4 wire system of course).


JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[petronila]

Hello Place,

I am agree with StarDelta. If you need the motor for 360 Volt the better choice is rewind.

Note:

Tn= New Turns per coil En= New Voltage(Desired)
To= Old Turns Per coil Eo= Old Voltage

Tn= To x En /Eo. This is true if the connection(delta or Wye), No.Circuits,Groups and Coils per Group remains constant. For 360 Volts The Turn ratio will be: 360/460 = 0.782 then the new turns per coil will be lower= 0.782 To, take account for the new 360 Volts motor will drain more Current(4.3 Amp) for it you most vary the Wire Size.(When the turns in a coil are changed, the wire size changes in order to provide the same slot fill) in this case will be greatest to support the new current.

The new Wire Size will be:

CMo=Old circular mil area, CMn = New circular mil area.


CMn = CMo x To/Tn then the CMn = CMo x To/0.782 To
= 1.278 CMo.

Best Regards

Petronila

 

[itsmoked]

I don't get that he needs a rewind! He's asking

"Motor needs rewind, is it?"

Bad English indeed but it is not a statement..

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[petronila]

Yes Keith,
Is clear, Place is taking account the chance to rewind the motor and is asking about this practice. I think too this is best way, also is asking "How to calculate the rewind date based on the original winding data?".

Regards

Petronila

 

[MotoDrv]

Yes "app" backwards. The drive is only going to put out up to what it gets as far as V and I some how flipped the 2 Vs. It was after midnight though %-)

I am changing my vote to the transformer
Skip the rewind..
The transformer will enable the motor to remain a stock version, keeping costs lower than a custom version and a heck of a lot easier to replace when/if it fails.

 

[place1234]

Dear all,thanks for your help.
Transformer and VFD is a effcient way to solve this problem. My question is rewind of this motor, is there any difficulty? See, in the case, there is one batch of these motors, say 1000 numbers, what is the solution? The solution is : rewind.

 

[jraef]

Ahhhhhhh, now we have a more complete story. Yes, if you are looking to salvage 1000 mis-wound motors, rewinding is the only viable approach. Petronila (and stardelta's) solution looks good to me, but admitedly I'm no notor winding expert. From your broken English (please don't take offense, that is just an observation), I think you are not in the US, but even so you may want to write in to the print magazine called Electrical Apparatus. They do not publish on-line unfortunately, but they have a question and answer column each month in which you can ask such questions.

http://www.barks.com/eacurr.html

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

So you are all saying that;
pulling a motor out... Sending it off to a shop... Getting it torn down... Stripped of windings.. Re-wound and coated... reassembling it... testing it... transporting it back.. reinstalling it(belts, gears, couplings.. etc., is going to be less costly than a few pallets of transformers purchased in bulk shipped one way??

Also the, "360V in 60Hz land", question has never been answered has it?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[powerjunx]

place1234,
With such numerous units, imagine 1000 motors... it's goes like a tricky decision for rewinding or hooking up with additional equipment like transformers or drives.
I'll go with rewinding but prior to send it to a rewinding shop. It is best to check the winding with a service provider's rewinder or technician to evaluate the winding for possible reconnection rather than complete rewinding.

 

[jraef]

Keith,
I was assuming that the motors were not yet installed. Good point.

 

[LionelHutz]

Hmm, if we're talking about 1000 motors in one plant then a large power transformer is the logical choice. Install a power system that uses a readily available voltage and frequency so that the motors are easy to source.

If I was looking to buy 1000 360V/60hz motors I would approach the different manufacturers to get a motor of the correct voltage and frequency without rewinding. There's got to be one out there that would accomodate this.

 

[edison123]

place1234

I am more curious about the 360 V/60 hz stuff. I am with Keith on this about this location of yours.

Oh, BTW, I am not with Keith about rewind since I feel lesser the components (however well-made, reliable etc. etc.), lesser the chances of faiure. (Sorry Keith )

I agree with Lionel also.