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speed variation

Created by: Pranab at: 6/1/2011 9:19 PM (7 Replies)

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6/1/2011 9:19 PM	Rate (0)
Pranab Posts: 63 Rating: (1)	Dear expert, Now we are commissioning a 7 nos. 6RA70 dc drive in rolling mill. These are IM2 and FM1 to FM6. I have done speed and current optimization properly of all drives. But there are speed fall at time of rod entering. What is the procedure to maintain the no variation of speed of motor in this application. Regards Pranab
Pranab Posts: 63 Rating: (1)
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6/2/2011 6:30 AM	Rate (0)
KSN Platinum Expert Joined: 8/25/2006 Last visit: 8/22/2025 Posts: 2218 Rating: (282)	Hello. In this case you need manual optimization of the speed controller. Main idea is to increase proportional gain and decrease reset time of speed controller. Also look at the following FAQ.

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6/2/2011 7:05 AM	Rate (0)
PISCEAN 2010 Diamond Expert Joined: 4/23/2010 Last visit: 11/23/2024 Posts: 8092 Rating: (882)	Pranab Dear expert, Now we are commissioning a 7 nos. 6RA70 dc drive in rolling mill. These are IM2 and FM1 to FM6. I have done speed and current optimization properly of all drives. But there are speed fall at time of rod entering. What is the procedure to maintain the no variation of speed of motor in this application. Regards Pranab Hello, How is set point fed? What type of feedback device used? Means analogue tacho or pulse encoder? How much speed fall is observed? Howthe drive isconfigured? In speed mode or torque control mode? Please provide more details.

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6/2/2011 8:15 AM	Rate (0)
Pranab Posts: 63 Rating: (1)	DEEPSTR2010 Pranab Dear expert, Now we are commissioning a 7 nos. 6RA70 dc drive in rolling mill. These are IM2 and FM1 to FM6. I have done speed and current optimization properly of all drives. But there are speed fall at time of rod entering. What is the procedure to maintain the no variation of speed of motor in this application. Regards Pranab Hello, How is set point fed? What type of feedback device used? Means analogue tacho or pulse encoder? How much speed fall is observed? Howthe drive isconfigured? In speed mode or torque control mode? Please provide more details. Dear epert, Drives are operated from LCS by Start/ Stop PB, Speed Increase/ Decrease PB and profibus system (CPU412). Drives are operated in closed loop by pulse encoder. Speed down upto 70-100 rpm at time of rod entering. Antarik subecha Pranab
Pranab Posts: 63 Rating: (1)
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6/2/2011 9:07 AM	Rate (0)
PISCEAN 2010 Diamond Expert Joined: 4/23/2010 Last visit: 11/23/2024 Posts: 8092 Rating: (882)	Ok. But how much is the speed prior to rod entry? Have you checked set point voltage fluctuation? How much armature current drawn by motor? How much is the rated current of motor? Have you checked the field/excitation current? Is it steady state or fluctuating? Is the field/excitation controlled by drive or it is controlled externally? Does the motor run in field weakening mode? Please check.

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6/3/2011 6:42 AM	Rate (0)
SKG Bronze Member Joined: 5/30/2008 Last visit: 10/22/2024 Posts: 135 Rating: (3)	Dear Pranab, I worked in a system where upto 2% lead speed is added to the stand motors even after speed controller is well-optimized.. When the stands run without bar, the motor runs with the added speed + set speed. But when the bar enters the stand, the motors run at set speed. The entry of the bar is sensed from torque sampling. You can see whether it is helpful. Shuvechhante, Shyamal

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6/6/2011 6:34 AM	Rate (0)
Pranab Posts: 63 Rating: (1)	SHYAMAL Dear Pranab, I worked in a system where upto 2% lead speed is added to the stand motors even after speed controller is well-optimized.. When the stands run without bar, the motor runs with the added speed + set speed. But when the bar enters the stand, the motors run at set speed. The entry of the bar is sensed from torque sampling. You can see whether it is helpful. Shuvechhante, Shyamal Dear Shyamal Thank you for giving this point. Please give parameter settings for torque sensing and how I will add 2% lead speed to the motor. Regards Pranab
Pranab Posts: 63 Rating: (1)
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6/8/2011 3:02 PM	Rate (0)
Ahmed Experienced Member Joined: 2/20/2007 Last visit: 11/19/2024 Posts: 122 Rating: (2)	Hello, Is it aWRM or BRM. because in such type of application we have lots of controllers which take this behaviour into consideration using compensation called Impact compensation. Also this should be taken care into PLC because it is process requirement. Hope this helps, Regards, Ahmed

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