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VFD Pumps
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Source：Internet Author：Unknow Pubdate：2008-03-19
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sualac (Civil/Environme)
29 Oct 07 20:49
Can anyone tell me what VFD pump is? Why do you use it? Can it be modeled in WaterCAD?
bimr (Civil/Environme)
30 Oct 07 2:46
http://www.alliantenergy.com/docs/groups/public/documents/pub/p012399.hcsp
http://www.mcnallyinstitute.com/13-html/13-08.htm
ltho98 (Civil/Environme)
31 Oct 07 13:01
A VFD pump is a Variable Frequency Drive pump. It will convert 1 phase to 3 phase typically and some can also act as a soft start depending on the size of the pump.
Its used in places where three phase is not available where you need three phase power to power a three phase pump. Normally, you would size the pump seperately and use a VFD to supply the 3 phase from the single source, but this is a cost-effective alternative.
字串3
PCU (Civil/Environme)
5 Nov 07 14:29
A VFD is an electrical system that controls an AC motor.
AC power is converted to DC power, then the DC supply altered, and then the DC is converted back to AC in order to control the speed of the motor. It doesnt convert 1phase to 3 phase.
The basics are shown here:http://en.wikipedia.org/wiki/Variable-frequency_drive
quark (Mechanical)
5 Nov 07 22:31
VFDs with single phase input and three phase output are quite common. All the reputed manufacturers have these devices.
BigInch (Petroleum)
8 Nov 07 8:27
Since you posted this in the water distribution and treatment forum, I assume you were looking for some inkling about how a VFD can affect something like water flowrate or water pressure. 字串8
You can use them to slow a motor down and, if the motor is a pump driver, you will slow down the flowrate and reduce the differential head of the pump.
See "pump affinity" estimate equations to predict the results the decrease in rotational speed has on flow and head. The basic premises are,
The New_Flowrate = Old_Flowrate * New_Speed / Old_Speed
The New_Head = Old_Head * New_Speed^2 / Old_Speed^2
The New_Power = Old_Power * New_Speed^3 / Old_Speed^3
The relationships are valid where pump efficiency does not change and where system flowrate is also roughly proportional to the change in pump's differential head.
http://virtualpipeline.spaces.msn.com
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