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Vfd For Winding Applications


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#1 Ramasubramanian

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Posted 20 September 2008 - 09:57 AM

Dear Friends,

Kindly suggest the suitable VFD for winding applications - in a coil from one spool to another.

Regards / VRS

#2 marke

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Posted 20 September 2008 - 10:09 AM

Hello Ramasubramanian

Most VFDs can be used for this type of application provided that the control system is appropriately set up and the VFD is sized correctly.
It is common to use some form of idler to "measure" the tension and control the drive speed.

Best regards,
Mark.


#3 Ramasubramanian

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Posted 20 September 2008 - 05:10 PM

Thanks Mark.

One more point that it is said that this VFD is based on closed loop . Can you explain !

#4 marke

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Posted 20 September 2008 - 07:51 PM

Open loop means that the system operates without any feedback. i.e. you tell it to run at a particular speed and it does so without taking any notice of what is happening.

Closed loop means that there is an element of feedback so that the drive alters it's performance (typically speed) in a manner to keep something equal to something else.
For example, on your winder, you have a pair of spools and the material is transferred from one to the other.
If you drive the take up spool only, and you set that to a constant speed, then as it fills up, the other spool will get faster and faster and the material transferring between the two spools will also get faster and faster. This is because the effective diameter of the two spools where the material is winding ON and Off is changing with the volume of material on the spools.
You could put a spring loaded idler wheel on the material between the two spools and adjust the speed of the take up spool so that there is always the same degree of deflection in the idler. This keeps the tension in the material constant, or you could past the material over a roller with a tacho feedback so that the speed of the material is kept constant.
There are a number of options and it depends on the machine design as to which should be used.

Best regards,
Mark.




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