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460/60HZ to 360V/60HZ

460/60HZ to 360V/60HZ

460/60HZ to 360V/60HZ

(OP)
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?

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

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...

RE: 460/60HZ to 360V/60HZ

OK, thanks Scotty.

RE: 460/60HZ to 360V/60HZ

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 wink

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

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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

Quote:

"Motor needs rewind, is it?"
  Bad English indeed but it is not a statement..lickface

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: 460/60HZ to 360V/60HZ

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     

RE: 460/60HZ to 360V/60HZ

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 dazed
 
I am changing my vote to the transformer2thumbsup
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.

 

RE: 460/60HZ to 360V/60HZ

(OP)
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.

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

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

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

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.

RE: 460/60HZ to 360V/60HZ

Place 1234,
1. "My question is rewind of this motor, is there any difficulty?" : No

2. "there is one batch of these motors, say 1000 numbers, what is the solution?": Perform an economic study to know if is better rewind all motors or Install a new Three phase transformer capable to handle this 1000 Motor load (2.5 MVA??). In the case your choice  is a  new transformer  what happeneed if the transformer fail? this will shut down all motors.By Reliability  I think the better choice is rewind all motors because you can have two or three motors like spare parts.

Another alternative is to look the internal winding connection, If the motor is connected for 460 Volts in DELTA you could reconnect the winding for two wyes and the motor will works fine at 380 Volts, then you can use the 360 Volts motors because you will be only 20 Volts below the new voltage rated (380V): 5% less.

Regards

Petronila  
 

RE: 460/60HZ to 360V/60HZ

With such small amperage, is there a way to look at the load and decide that nothing needs to happen?  For example, is the load pulling 3 amps at the low voltage at each motor, if so, that is under the limit of the motor. Does the motor have a high service factor?  Could you rerate the motor with a smaller service factor?

RE: 460/60HZ to 360V/60HZ

Place123.

Since the frequency remains 60 HZ, and If the very same orginal connection and circuits are left in the new winding (n), the original  turns per coil (TPCo) will be reduced and the original conductor cross section area (Acuo)increased.

    TPCn = TPCo*(360/460)= 0.7826*TPCo
     Acun= Acuo*(460/360)=1.278*Acuo

RE: 460/60HZ to 360V/60HZ

I agree with the writers that suggest the transformer solution, but only because of the high number of motors.

If it was a single or a few, I would scrap them and install new motors with the correct data, rewinding is much too costly, at lesst in high wage countries.

Greetings Aksel.

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