I have 480V 3 phase at a panel but ....

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Mrat

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I have 480V 3 phase at a panel but the pump/aerator for a lake is 3 phase 440V and the manufactuer says it will not work on 480V. I have always assumed 440V/480V is much like 220V/240V, just a variation in areas or time period. I have assumed wrong? Thanks, Mark
 
Take a look at the Tables at the end of Article 430. (430.250) Unless the equipment you describe is foreign, any system of 440V - 480V will be sufficient for this motor.
 
motor

motor

I agree with Brian....from a liability standpoint, it sounds like buck & boost time.
 
brian john said:
BUt If the manufacture says NO and the pump fries FOR ANY REASON, you may be furnishing a new pump.

Buck Boost

http://www.sola-hevi-duty.com/products/transformers/pdfs/bboost/bbselect3ph.pdf
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who supplied the pump?

if some weird voltage is needed, it is their problem to supply it.

i have a real hard time believing any US manufacturer would supply anything only rated for 440V 3 phase. And if it is foreign, it might well be designed for 50 hz. I suspect more investigation is due. It may be that whoever you talekd with at the pump manufacturer was just mistaken.

<added>
It may also be that by the time you take into account any VD, you may only have 440V at the motor itself.
 
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Thank You guys, I am going to get the 440V motor. I suspect that it is an uninformed dealer. Its a very small motor, only 3/4 HP. It is located in a pump house with a large pump motor. There is 120/240V but just as a lighting circuit since the transformer is only 1KVA.
 
Manufacture often mis-quote numbers 240, 440 what is a few 100 here or there.

I was not suggesting you eat the cost of the buck boost, only that you would eat the pump if you applied the wrong voltage per the manufacture.
 
brian john said:
Manufacture often mis-quote numbers 240, 440 what is a few 100 here or there.

I was not suggesting you eat the cost of the buck boost, only that you would eat the pump if you applied the wrong voltage per the manufacture.
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It was Bryan Holland's post that convinced me.
 
Motors are usually rated lower than nominal system voltages. While we usually use 120v, 240v, 480v, etc., motors are rated at 115v, 230v, 460v, etc.

A given motor will almost always require less current, not more, when the voltage is at the higher end of the motor's voltage range.
 
LarryFine said:
Motors are usually rated lower than nominal system voltages. While we usually use 120v, 240v, 480v, etc., motors are rated at 115v, 230v, 460v, etc.

A given motor will almost always require less current, not more, when the voltage is at the higher end of the motor's voltage range.
Click to expand...

Thanks Larry, I figure I'm always safer with some over voltage on a motor if anything then under because of the current.
 
I agree with the Buck-Boost, It's a small motor and a lot of voltage. Less than 10% over the rated voltage and if the motor rep so no go, that should tell you something. Will it then be installed as per instructions?

I also disagree with using Table 430.250 as a (It's OK), I thought the Tables were used for conducter sizing per 430.6 (A)(1). Am I missing something?

R
 
This article helped convince me to get the 440V compressor.

http://www.motorsanddrives.com/cowern/motorterms11.html

Well that plus the thought of "what company would design a lake aeration unit that has a motor voltage that is unique enough that it would limit many of us who have 480V at our service" To have to buck/boost to allow their product to work seems to me that its time for them to get a different motor supplier. I think it must have been lack of familiarity with electricity, either that or after the unit arrives, it will be me with the lack of electrical knowledge and it wil be me bucking the power. I think a bucking transformer will be a little less then a larger 480V to 240V larger KVA transformer to pick up the additional motor load. I already have the 480V/240V/120V transformer for the lighting.
 
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According to NEMA MG1:

12.44 VARIATION FROM RATED VOLTAGE AND RATED FREQUENCY
12.44.1 Running
Alternating-current motors shall operate successfully under running conditions at rated load with a variation in the voltage or the frequency up to the following:
a. Plus or minus 10 percent of rated voltage, with rated frequency for induction motors.
b. Plus or minus 6 percent of rated voltage, with rated frequency for universal motors.
c. Plus or minus 5 percent of rated frequency, with rated voltage.
d. A combined variation in voltage and frequency of 10 percent (sum of absolute values) of the rated values, provided the frequency variation does not exceed plus or minus 5 percent of rated frequency, and the voltage variation of universal motors (except fan motors) does not exceed plus or minus 6 percent of rated voltage.

With that said, 480V is 109.1% of rated voltage of the motor, so technically it should work. If you factor in a 3% drop from the main service to the motor then your looking at around 466V at the motor terminals. The problem that could occur, is that you do not have any control over the utility supply, and it could legitimately fluctuate such that that 480V becomes 500V. At that voltage you will be over the rated at the motor terminals, and could cause damage to the motor. If you have a transformer that is within your control, then I would think about tapping it at the +2.5% tap (on the LV side, or -2.5% on the HV side), which would keep the voltage at the motor within 110%, even if the utility goes high.
 
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