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6/9/2014 5:28 AM | |
Posts: 262 Rating: (45) |
Hi, Both overload and short circuit settings are some %age of Rated current of ACBs. Say, for 1600A ACB, 0.5 Setting is 800A as Overload setting. That means Over 800A ACB will trip as per IDMT. As you are aware for Short Circuit, there are two Short Circuit protection:- Short Circuit with Delay and Instantaneous Short Circuit. Again Short Circuit delay is dependend on Rated current of ACB, Setting Knob at 1.25 means 1.25*1600A = 2000A onwards it will follow IDMT Curve of Short circuit. You can provide an additional delay ( if required) thru' tsd knob. So, 3WL will trip between 800A to 2000A as Overload and 2000A onwards Short Circuit. Instantaneous is something Unquie in 3WL i.e. 20times of In i.e. 20*1600= 32000A That means even if the current is more than 32KA ACB will overlook all the settings and Trip as per its IDMT of Instantaneous setting. I have Simulated the above situation and attaching an IDMT of 1600A 3WL with ETU25B having settings as stated above i.e. overload from 800A onwards and S/C at 2000A onwards. Hope this is clear. Apart from this any testing if you want to carryout to check the behaviour of ACB on overload, shortcrcuit, Ground fault or healthiness of ETU 25B, you can purchase one no of 3WL9111-0AT32-0AA0. Just Type this MLFB in the above Search option to get complete manual of it... or else click https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=3WL91110AT320AA0&caller=view AttachmentC:\Users\in210417\Desktop\ETU25B.pdf (657 Downloads) |
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