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EOT CREANE

4/5/2012 11:05 AM	Rate (0)
yogesh1 Posts: 5 Rating: (0)	I am involved in a project of EOT crane in which 3 ph. squiller cage induction motors are used for ct & lt with g120 ac drives of pm240. the drives are used in SLVC mode the motor response is not as fast as in contactor logic for inching operation.tryied ramp-up, magnetising current, time but no response.--------------pl.help
yogesh1 Posts: 5 Rating: (0)
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4/6/2012 6:57 AM	Rate (0)
Vithani Platinum Member Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	how many motors are connected with single drive? As far as I know, normally in LT, two motors are connected in One drive. If this is the case then you should never use SLVC - it is not recommended Please give some more detail. What exactly you want? and what you are facing? Do u want to start drive immediately when you press Button? If it is, then try setting minimum RampUp At what setpoint you wanna run during this inching operation?
	I dont Like people driving Fast, thats the reason I overtake them ;)
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4/6/2012 1:48 PM	Rate (0)
yogesh1 Posts: 5 Rating: (0)	yes i am using 2 motors for LT. I want motor should get start immadiately after pressing button.I kept ramp up time 1 sec. I think its about Magnetisation,when i give continous ON command to drive & then pass setpoint of 200rpm it gives better response but not as best as contactor logic operation. I use v/f mode also with voltage boost but didnt got best result.
yogesh1 Posts: 5 Rating: (0)
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4/6/2012 8:36 PM	Rate (1)
Vithani Platinum Member Joined: 7/8/2009 Last visit: 6/7/2025 Posts: 1977 Rating: (479)	Well then, you must not use SLVC Have a look at following FAQ http://support.automation.siemens.com/WW/view/en/14390055 Now try making some more smaller ramp time say 0.5-0.8 Sec And what I feel is, itshould befaster enough. Because I assume your motor is 4Pole, then Rated speed will be 1500. In this case you want to run at 200RPM which is at 6.7Hz so for 1sec Ramp up time, it will take 0.13 sec to reach your desired setpoint Now I think thats faster enough but still you can try setting ramp up still smaller And what is Magnetisation time you have set? You can reduce a bit but dont make it much lower Contactor Logic can give instant start-stop but at that time you will get full speed so crane will move with a Jerk and may be due to speed differnce also you may not able to compare clearly Regards Devesh Vithani
	I dont Like people driving Fast, thats the reason I overtake them ;)
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