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Pumps And Vsd's


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#1 shaun50-60hz?

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Posted 02 October 2006 - 01:13 PM

What constitutes running a motor supersycronous ?, will a standard abb drive convert the output from the input voltage of 400v/50hz to 480v and 60hz to run a 60hz American motor in the uk?
Can standard 50hz motors be driven past 50hz, does anyone have experience of driving them and the resulting reliability?
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#2 jOmega

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Posted 02 October 2006 - 04:25 PM

Shaun

The drive cannot manufacture voltage.

you can operate a 460/60 motor to 380/50 without

reducing the V/HZ applied to the motor.

Otherwise, you could apply a step-up transformer to the mains input side of

the VFD to boost the input voltage to 460 or 480 ....

That would then develop sufficient DC Bus voltage to allow you to

set-up the VFD to operate to 460/60

(Having a 50 Hz supply is not a consideration; its a non-issue) as the VFD will invert the DC bus

voltage to variable frequency AC voltage.





#3 kens

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Posted 02 October 2006 - 08:39 PM

Hi Shaun, as jOmega has said the drive will not increase the voltage. You can run the motor at 400V 60 Hz however you will see a decrease in the torque out put. I assume that you are talking about a pump application. Depending on the sizing of your system this may not be an issue (ie if the motor is oversized for the pump). If this is a centrifugal pump it will be at maximum torque requirement at 60 Hz so you may have problems. I have often oversped 50 Hz motors generally on fans but the caracteristics are the same. It will really come down to the sizing of all your components.
Ken
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#4 easyser

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Posted 03 October 2006 - 01:11 PM

We have requirement for running 440 V 60 Hz motor using inverter from a 415 V 50 Hz mains.
It has been confirmed by one of our vendors ( reputed one ) that if we use active front end the inverter can give output of upto 500 V AC 60 Hz from 415 V 50 Hz input voltage , suitable for driving 440 V 60 Hz mototrs, without the use of a step up transformer.

Is the vendor info correct ?

Thanks in advance.
easyser

#5 jraef

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Posted 03 October 2006 - 07:39 PM

QUOTE(easyser @ Oct 3 2006, 06:11 AM) View Post

We have requirement for running 440 V 60 Hz motor using inverter from a 415 V 50 Hz mains.
It has been confirmed by one of our vendors ( reputed one ) that if we use active front end the inverter can give output of upto 500 V AC 60 Hz from 415 V 50 Hz input voltage , suitable for driving 440 V 60 Hz mototrs, without the use of a step up transformer.

Is the vendor info correct ?

Thanks in advance.
easyser


If he is, he is about to get VERY wealthy because he has cracked the secret of creating voltage from thin air!
"He's not dead, he's just pinin' for the fjords!"

#6 jOmega

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Posted 03 October 2006 - 08:51 PM

QUOTE(jraef @ Oct 3 2006, 02:39 PM) View Post

If he is, he is about to get VERY wealthy because he has cracked the secret of creating voltage from thin air!



JRAEF .

You might just want to back-off a tad on this one.

ABB claims (Principal Engineer as opposed to marketing type) that it is possible to obtain an output voltage that is greater than the supply voltage with their active front-end drive.

I attended an IEEE IAS Chapter meeting last year where he presented that concept; albeit not in sufficient depth that I'd be able to regurgitate it to you at this time.

I'd be happy to either put you in touch with him .... or ask for more detail on behalf of all of us.

My immediate question would be ....... Is it RMS FUNDAMENTAL voltage or RMS total voltage.
As you know .... only the RMS Fundamental voltage produces useful torque at the motor shaft.

Regardless..... I would venture to say that their Active Front End Drive, with attendant supporting hardware items, will be a whole lot more expensive than a garden variety VFD with a front end step-up transformer.

Ya think ?

#7 jraef

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Posted 03 October 2006 - 09:31 PM

Yeah, now that you made me think about it, small VFDs do it on the DC side with a voltage doubler circuit, so if you had enough hardware I suppose it is possible. That said, I think your point about cost is dead on. A typical active front end VFD is around twice the price of a standard drive. An autotransformer or even an isolation transformer would be significantly cheaper. If on the other hand you were buying the active front end drive for other reasons, that would be a side benefit.
"He's not dead, he's just pinin' for the fjords!"




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