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Current fluctuating in SLVC mode

Created by: Vithani at: 11/23/2009 9:49 AM (5 Replies)

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11/23/2009 9:49 AM	Rate (0)
Vithani Platinum Expert Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	Dear Experts, I have apllication of Exhaust fan which is controlled by analog input setpoint from DCS control. Its running in SLVC mode. V/F is not possible because it was drawing very high current. Now my problem is that, when ever any change in setpoint is occur, current is fluctuating very high. For example, setpoint is changed to 25% to 35 %, at that time, current will go from 72 amp to 130 or some times 150 amp and then bect to 75-80 amp. Due to this fluctuation, we can not run VFD in auto mode. I uploaded parameter file. Any suggestions?? Please give reply ASAP Regards, Devesh Vithani Attachment exhaust.pdf (419 Downloads)
	Last edited by: Vithani at: 11/23/2009 9:51 AM I dont Like people driving Fast, thats the reason I overtake them ;)
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6/2/2010 8:55 AM	Rate (0)
Vithani Platinum Expert Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	Well, I performed tunning on load and played with parameters of speed controller as well as current controller Now situation is well within limits. Still I am getting fluctuation but its now far better Regards, Devesh
	I dont Like people driving Fast, thats the reason I overtake them ;)
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6/2/2010 10:27 AM	Rate (0)
Gary.Hare Posts: 101 Rating: (8)	Try reducing your speed controller. For a large fan P240 I would normally set around 500ms. Try increasing and decreasing P235 and checkthe results. Also increase the ramp time to the maximum tollerated by the system. This will help greatly. If you are seeing large current fluctuations then your system is too harsh for the application. Trace your set speed and actual speed and check for any large overshoots. For a fan you don't really want an overshoot at all.
Gary.Hare Posts: 101 Rating: (8)
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6/2/2010 12:03 PM	Rate (0)
Vithani Platinum Expert Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	Hello gary.hare Thanks for reply but as I said, problem has been resolved now. Post is just to share what I did to solve. The backup which I uploaded is older. I tunned speed controller and current controller on load and now its working fine. There is still some fluctuations, but for that I should use Close loop VC instead of SLVC. Anyways, Thank for reply, Regards, Devesh
	I dont Like people driving Fast, thats the reason I overtake them ;)
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3/12/2013 7:32 AM	Rate (0)
DuyNT Regular Member Joined: 6/19/2008 Last visit: 9/5/2025 Posts: 8 Rating: (0)	Hi Vithani, Now, I havethis problemwith SLVC mode in Sinamics G150. How did you fix the current fluctuating? Thanks Attachment D:\temps\SLVC.pdf (403 Downloads)

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7/7/2013 3:44 AM	Rate (0)
Vithani Platinum Expert Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	Wow's Hi Vithani, Now, I havethis problemwith SLVC mode in Sinamics G150. How did you fix the current fluctuating? Thanks Hello Wow's Perhaps your problem might have solved now.. But i did manual Tunning for speed controller with load. Changed gain and time parameters, checked its effect and set to best possible values Regards, Devesh
	I dont Like people driving Fast, thats the reason I overtake them ;)
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