adccommunitymod (AutomationDirect) asked a question.
Tach vs Encoder
Created Date: December 06,2013
Created By: keklon
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Hello, I need some advise on an application where I need to maintain constant surface speed on a paper winder. We plan to replace the DC drive with a VFD and maintain the speed of the (VFD) winder with feedback from a tachometer placed on the web. Does anyone have any other suggestions for this application? Can I input the signal from the tachometer directly to the VFD or do I need a separate controller?
Created Date: December 06,2013
Created by: scott.lawrence
I prefer, when using webs, direct contact to the web itself.
these guys have some ... most of their web mounted wheels are quad outputs. You can also have them custom built.
http://www.photocraftencoders.com/Wheeled%20Encoders.htm
Created Date: December 06,2013
Created by: bcarlton
The solution will almost totally depend on the VFD capability. If you can please post information on the VFDs.
Created Date: December 07,2013
Created by: Gerry G
Most dc tachs generate a set voltage per rpm something like 100v per 1000rpm depending on the type, then use a tunable voltage to voltage converter it will be something like 0-200v in 0-10v out, any drive out there will accept 0-10 speed signal. You may need to run thru a plc if there is going to be any tuning to the speed signal on the fly.
If you want to post a little more detail on the application.
Created Date: December 07,2013
Created by: bcarlton
The tach would be a feedback not the command signal. You would need a VFD with a PID type function. Lacking that the comparison of the command and feedback would have to happen in an external controller. For another method here is an example of Sensorless Vector drives which are very accurate with speed control and it can accept an optional encoder feedback for even better speed control.
Created Date: December 06,2013
Created by: keklon
Hello,
I need some advise on an application where I need to maintain constant surface speed on a paper winder. We plan to replace the DC drive with a VFD and maintain the speed of the (VFD) winder with feedback from a tachometer placed on the web. Does anyone have any other suggestions for this application? Can I input the signal from the tachometer directly to the VFD or do I need a separate controller?