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SOFTSTARTER WORKİNG PRENCIBLE

Created by: erkanozdemir at: 4/24/2010 10:20 AM (3 Replies)

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4/24/2010 10:20 AM	Rate (0)
erkanozdemir Posts: 19 Rating: (0)	hi how can i learn internal structure of siemens softstarter . i mean in pratical we knows to entry some value for parameters and it works but if i can learn some specials informations about softstarter then iwould find solution in some matter . for example recently i had a question about softstart when it was started for 37 kw motor .ramp current reached till 100 A and 10 sn later down to nominal value ( 67 A) but when it reached to nominal current value . it stopped suddenly . and there wasn't any fault messageon the screen therefore i didn't understan what happened .so can you help me pls to learn to detailed informs which softstarter's internal working prenciples. have a nice days
erkanozdemir Posts: 19 Rating: (0)
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4/24/2010 2:12 PM	Rate (0)
fritz Diamond Member Joined: 10/7/2005 Last visit: 11/6/2024 Posts: 3026 Rating: (1056)	Hello erkanozdemir THIS Siemens 3RW44 Sirius Soft starter manual has quite some detailed technical know how in it which may be what your are after (and you can search https://support.automation.siemens.comfor manuals and info about other Siemens Soft Starters). If you google "Theory of Soft Starter" you'll find plenty of additional siteswith info aboutthe subject matter. I'm not too sure though if all this infowill help you being able to explain your specific problem. It sounds to me as if either the motor does not manage to reach full speed at the end of the "soft start" or there is a problem with the bypass contactor (10 s is a commonly used startup time), but I can only speculate based on your info. Ideally you'd go to site and check/verify online in theSoftstarter what is happening on startup (the 3RW44 for example has somereallygood inbuilt diagnostics as well as trend capabilities if used in combination with Softstarter ES whichgreatly help with the commissioning and troubleshooting effort). I hope this helps
	Last edited by: fritz at: 4/24/2010 3:10 PM Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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4/24/2010 10:05 PM	Rate (0)
Ayman Elotaify Platinum Member Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	Hello, I think the following tip will help you The theory of the softstarter And back to your problem, I think that you have to tune the softstarter parameters. Here's in this thread guides forcommissioning ofall Siemens softstarters families. In this thread, you will found flowcharts for fine tuning. Softstarter Quick Commissioning Regards,
	Ayman Elotaify
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4/27/2010 12:15 PM	Rate (0)
LesPaul Posts: 467 Rating: (59)	Hello erkanozdemir, there are some good comments regarding your request on the technical forum. Essentially the manuals are the best solution to find out the reason of some reactions. Normally the softstarter 3RW40/3RW44 has the same internal logic to start the motor and switch to the internal baypass contactors. The run-up detection is available at 3RW40 and 3RW44 works as follows: 1) The current must drop below the limit of 0.5 x starting current (3RW4 determines the starting current directly when switching on) and 2) The current has to be <1.5 x In (In = set rated current) If the switch on happens during a rotating motor, then the soft starter waits until the thyristors are fully controlled (normally after expiration of the set ramp time). Additionally the current has to be constant for 2s (and of course smaller than the respecting rated current of soft starter). If the softstarter switch off without any error message it could be that the start command is off (or lost) or the control voltage was going down. regards
LesPaul Posts: 467 Rating: (59)
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