Powerflex 700 VSD

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Anonymous Poster #1	Powerflex 700 VSD 04/09/2014 5:40 AM
	I am using a 45kw powerflex on a 15kw 4 pole motor, On every start the motor turns about 1 rev. backwards before it runs forward.We have two of these set ups and both does exactly the same thing.I have one drive set up on sensorless vector, done autotune and the other on V/Hz.I have also set both to unipolar. I am using 4-20 to control speed, and could not find any problems with the 4-20. Any ideas why it will go in reverse for about a second?
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The.Tinkerer Guru Join Date: Apr 2012 Posts: 732 Good Answers: 17	#1 Re: Powerflex 700 VSD 04/09/2014 11:01 AM
	Likely it is the dynamic braking which initiates each time you power it on. __________________ common knowledge...less common than common sense
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#2 Re: Powerflex 700 VSD 04/09/2014 11:48 AM
	What is the driven load? A common overlooked problem is that if there is some sort of parking/holding brake, it is released by the VFD immediately, but it takes a second for the ramp settings to allow the VFD to generate enough torque to keep the load from rotating it backward. The other possibility to consider, if you have communications enabled, is that something is loading a value of 1 or 2 into parameter F061, the Autotune function. It is supposed to be a one shot deal, where it Resets to zero after performing the Autotune procedure. But I've seen it where people do this over the network and forget to remove the code in a program, so it does it again every time it restarts. __________________ All I every really wanted to be, was... A LUMBERJACK!.
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SimpleMind Guru Join Date: Sep 2009 Posts: 1056 Good Answers: 88	#3 Re: Powerflex 700 VSD 04/09/2014 12:27 PM
	This behavior can very well be drive parm related, but you must rule out any load, mechanical brake, imbalance or elasticities related reasons first, then start messing with programming the drive. If you have done the homework about that issue we can continue to drive. In a sensored config, the drive, if configured as reversible, must determine the rotation direction by the sensor feedback at every start, and specially if the pulses per rev count is small, you can see this phenomenon. If this is your case note that the drive has a default original searching direction (that obviously is the reverse than the one you want) and it might be changeable programmatically, or you just reverse two phases and invert the rotation in drive programming. If you use a sensor-less vector config, something could be wrong with your source of 4-20ma control input. There may be a latency on the original current (e.g too much added capacitance at control or PLC side that the drive can't tolerate) but still the drive must have been configured as reversible, and if this is not needed, it MUST be excluded on programming. S.M. __________________ Life is complex. It has a real part and an imaginary part.
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Anonymous Poster #1	#4 Re: Powerflex 700 VSD 04/10/2014 2:18 AM
	Thank all for the help, problem was that the flying start was enabled.
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Anonymous Poster (1); JRaef (1); SimpleMind (1); The.Tinkerer (1)

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