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Vfd For Air Classifier In Cement Plant


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#1 gaurav1981

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Posted 06 March 2008 - 05:53 AM

Dear All,

Does anyone knows about the operating behaviour of this application?

i'm mentioning below the details i got from the customer:

It is a fan, motor rating 75Kw, gearbox between motor & fan, starting with damper open, altitude 1600 to 1700 m.

Whether we should consider starting duty as 120% or 150%?

Thanks & Regards,
Gaurav

#2 marke

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Posted 06 March 2008 - 06:33 PM

Hello Gaurav

A fan is what is known as a variable torque application where the required torque increases as the speed increases.
You do not need any overload capacity ass there are no transient loads, so select the drive on 120%

Best regards,

#3 gaurav1981

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Posted 07 March 2008 - 07:01 AM

Dear Marke,

Thanks for the reply.

Regarding derating w.r.t altitude, i referred a post on the forum mentioning the same.

On that post derating w.r.t altitude was in terms of current rating & voltage rating.

System voltage is 415V +/- 10%.Considering altitude of 1600-1700 m , there will be a derating of 6-7%, so we have to go for 480V or 500V drive.

Q.Considering this new selection of drive voltage rating, we have to check the voltage band of the drive & see whether 415V falls in this band or not.
& also does the output capacity/parametrs of drive remains same in the whole band.

Thanks & Regards,
Gaurav.

#4 marke

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Posted 07 March 2008 - 07:49 PM

Hello Gaurav.

You should not need to derate the voltage, only the current.
As you increase in altitude, the density of the air reduces so the cooling effect is reduced. Therefore you need to reduce the heat losses to prevent the drive from overheating. Voltage should not be a problem.

Best regards,




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