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Slip Ring Motor |
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 Feb 13 2009, 11:37 AM
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#1
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 Group: Members Posts: 1 Joined: 12-February 09 Member No.: 5,148  |
QUOTE (bob @ May 8 2008, 09:05 AM)  Thanks Mark. I shall keep you informed. Kind regards. Bob  Hiwe are using two 1150 kw, 6.3 kv slipring motors with two liquid starters to rotate a cement ball mill, the problem is that when we start the mill ,both motors start together through same breaker, and start the mill to rotate but after rotating approximately at 45 deg in forword direction mill rotate back at about 30 deg and then again in to forword direction, it shows that motors torque at that time is less than the media weight which force it to run back . i want to increase the torque of both motors that they should not allow the mill to rotate back. thanks Bhatti Bestway Cement Pakistan |
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Jul 25 2009, 04:33 AM
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#2
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Junior Member Group: Full Member Posts: 8 Joined: 25-July 09 Member No.: 5,969 |
QUOTE (Bhatti @ Feb 13 2009, 12:37 PM) Hiwe are using two 1150 kw, 6.3 kv slipring motors with two liquid starters to rotate a cement ball mill, the problem is that when we start the mill ,both motors start together through same breaker, and start the mill to rotate but after rotating approximately at 45 deg in forword direction mill rotate back at about 30 deg and then again in to forword direction, it shows that motors torque at that time is less than the media weight which force it to run back . i want to increase the torque of both motors that they should not allow the mill to rotate back. thanks Bhatti Bestway Cement Pakistan Hello Bhatti, I wonder that during that situation when the mill rotates back. There is no vibration? I think that this vibration must trip the motor this case. The only way to increase the torque is to increase the voltage applied to the motor. Could you check the transformer supplied power to these motors available with Tap changers. Just increase the voltage and see how it react. How many step of the starting resistors? Regards, Hien |
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Jul 25 2009, 04:40 AM
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#3
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Junior Member Group: Full Member Posts: 8 Joined: 25-July 09 Member No.: 5,969 |
QUOTE (HienN @ Jul 25 2009, 05:33 AM) Hello Bhatti,
I wonder that during that situation when the mill rotates back. There is no vibration? I think that this vibration must trip the motor this case. The only way to increase the torque is to increase the voltage applied to the motor. Could you check the transformer supplied power to these motors available with Tap changers. Just increase the voltage and see how it react. Or just adjust the range of the liquid starter to adequate with the load moment. Sound right? Regards, Hien |
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Jul 25 2009, 08:32 PM
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#4
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Posting Freak Group: Moderator Posts: 2,336 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Hello Bhatti
With a slip ring resistance starter, it the resistance is too high or too low at any given speed, the torque will be low. If the resistance is too high, the torque will be low and the stator current will also be low. If the resistance is too low, the torque will be low and the stator current will be high. Check the stator current and if it is less than 200%, you can reduce the rotor resistance to increase the torque. If the stator is greater than 300%, then you must increase the rotor resistance at that speed. You can reduce the resistance by increasing the area of the probes that is in the liquid, or by increasing the strength of the liquid. It depends on the type of starter. Best regards, Mark. -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
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Oct 5 2009, 08:04 AM
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#5
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Group: Members Posts: 1 Joined: 5-October 09 Member No.: 6,732 |
Hi
we have done a lot of ball mill applications. It is necessary to know all the data of the equipment to make the right calculation. Data of the mill, data of the motor, gearbox, data of the starter ... Just let me know and perhaps I can give you a solution. Jürgen QUOTE (Bhatti @ Feb 13 2009, 01:37 PM) Hiwe are using two 1150 kw, 6.3 kv slipring motors with two liquid starters to rotate a cement ball mill, the problem is that when we start the mill ,both motors start together through same breaker, and start the mill to rotate but after rotating approximately at 45 deg in forword direction mill rotate back at about 30 deg and then again in to forword direction, it shows that motors torque at that time is less than the media weight which force it to run back . i want to increase the torque of both motors that they should not allow the mill to rotate back. thanks Bhatti Bestway Cement Pakistan |
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