7/4/2013 11:41 AM | |
Joined: 3/17/2013 Last visit: 8/25/2024 Posts: 481 Rating: (43) |
Hi Vithani, In general my understanding is OVERCURRENT is instantaneous and drive should trip immediately, where as current limit waits for the motor current to be above 100% and thereby reduces speed, so that current is within 100% limit. I mean for motor earth fault, phase to phase short, IGBT fail OVERCURRENT trip should be the drive design, but not reducing speed unlike overloading of motor Regards, Vijay |
7/4/2013 4:58 PM |
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Joined: 3/17/2013 Last visit: 8/25/2024 Posts: 481 Rating: (43) |
Gents, Where is my post. In the list it is showing as posted at 11.41 am, but is invisible? Regards, Vijay |
7/4/2013 5:04 PM | |
Joined: 7/8/2009 Last visit: 8/5/2024 Posts: 1976 Rating: (477)
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Hello Vijay, thanks for your post If you have read some other posts in this conference, you may have noticed that so many times we need drive to trip instantly or within time limit defined by us - and as drive doesnt do it by it self, we need to program that and my post is just to share with others that what logic i am using. This may be useful for so many people because i know, so many customer had demanded me to set current limit and time to trip Hope you get the point of providing Overcurrent trip logic Regards, Devesh |
I dont Like people driving Fast, thats the reason I overtake them ;) |
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7/5/2013 5:47 AM | |
Posts: 205 Rating: (11) |
hi vithani thanks for your fast replay....... this logic is working perfactly ok in mm440 i have to check this logic in sinamics g120 series also then come back to you after checking in sinamics
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This contribution was helpful to1 thankful Users |
7/6/2013 7:02 AM | |
Joined: 3/17/2013 Last visit: 8/25/2024 Posts: 481 Rating: (43) |
Dear Vithani, My understanding is that IOC shall always be instantaneous trip, but not to wait for any time. For example IGBT fail, inverter output short cirucuit... etc. Where as current limit waits for motor load to cross some setting like 100 % then no harm to motor except reducing load to within norms by folding back the speed. In most of the drives, as soon as drive receives start command it checks for ouput short and trips off immediately w/o pumping real current to wait till very high short circuit current is drawn by motor. Regards, Vijay |
7/6/2013 7:11 AM | |
Joined: 7/8/2009 Last visit: 8/5/2024 Posts: 1976 Rating: (477)
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Whats problem if i want to trip on certain Limit on certain time? Please read following discussion /tf/WW/en/Posts/93606 Because of this setting, our GMU breakage is stopped and DEEP also requires same and during comissioning, i encounterd so many cases where this settings were required Regards, Devesh Vithani |
I dont Like people driving Fast, thats the reason I overtake them ;) |
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8/5/2014 8:13 AM | |
Joined: 1/22/2012 Last visit: 6/19/2024 Posts: 9 Rating: (0) |
Does it mean that the normal response to the overload condition "p640" is a speed reduction not trip?? |
8/6/2014 6:00 PM | |
Joined: 7/8/2009 Last visit: 8/5/2024 Posts: 1976 Rating: (477)
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YES But remember, it is for OVERLOAD and not for OVERCURRENT(output shortcircuit) Regards, Devesh Vithani |
I dont Like people driving Fast, thats the reason I overtake them ;) |
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