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Effects of Short Circuit to S7 300 modules and its power supply

Created by: boycemento at: 6/6/2011 4:26 AM (8 Replies)

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6/6/2011 4:26 AM	Rate (0)
boycemento Experienced Member Joined: 4/22/2010 Last visit: 6/5/2024 Posts: 82 Rating: (1)	Hi Experts, What will happen to a S7 300 module (SM321) and its power supply (SITOP) if you accidentally short the power supply lines of that signal module? Hope you can help me with this.. Thanks and best regards, lordgalen

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6/6/2011 7:54 AM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 1/2/2025 Posts: 4518 Rating: (841)	lordgalen Hi Experts, What will happen to a S7 300 module (SM321) and its power supply (SITOP) if you accidentally short the power supply lines of that signal module? Hope you can help me with this.. Thanks and best regards, lordgalen Hellolordgalen, Please tell us the MLFB of the SM321 you have. For SITOP power supply, there's a limitation dip switch B (On position) which linit the output current to 1.15 Ia. SITOP Modular Power Supply Manual Protective and monitoringfunctions Static current limitation: Typ. 1.15 x Ia Behavior under short-circuit conditions (output):Constant current / shutdown, directly via selectorswitch B Attachment BA_6EP133x-3BA00_C98130-A7548-A001-08-6419_201009.pdf (272 Downloads)
	Ayman Elotaify
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6/6/2011 5:11 PM	Rate (0)
Aret Posts: 2348 Rating: (265)	General consideration - as soon power doesn't go through DI module (short-circuit before - in PS supply lines, so DI module receives 0V - no voltage diff between L+ and M) - DI module wouldn't suffer. But to say exact it would be nice if you place powering diagram (including earth connections) here with short-circuit shown. As for PS itself - see post above.
Aret Posts: 2348 Rating: (265)	Last edited by: Aret at: 6/6/2011 5:12 PM
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6/7/2011 8:03 AM	Rate (0)
boycemento Experienced Member Joined: 4/22/2010 Last visit: 6/5/2024 Posts: 82 Rating: (1)	Hi Aret, Thanks for the response..Another question, what if power goes through the DI module? Or an unexpected voltage coming from the MCC pass through the signal cables connected to the front connectors of that DI module?Will it break the DI module and shut down the power supply (SITOP 24 V supply)?Or will it just break the DI module and doesnt affect the power supply (SITOP 24 V supply) at all? Regards, lordgalen

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6/7/2011 8:23 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	If you get 24VDC to the input of signal module - this is normal and considered as logical "1". If you get L+ on M pin from the same PS - see my post above. If you get it from another source - what would happen depends on where from you got this. And finally if you get high voltage to input you will burn DI module in best case. In worst case it would be disruption to power supply lines or backplane bus - consequences may be till total station wipe-out (or even whole cabinet - circuit path may be very weird). Generally galvanic isolation should take care of such things, here everything depends on voltage you get on input and isolation voltage, declared for module, and cabinet construction. Thats the reason why many companies use intermediate DI/DO relays - burning relay is much cheaper then burning DI module:^)
Aret Posts: 2348 Rating: (265)
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6/7/2011 8:36 AM	Rate (0)
boycemento Experienced Member Joined: 4/22/2010 Last visit: 6/5/2024 Posts: 82 Rating: (1)	Hi Aret, Thanks again...I forgot to attach the wiring diagram..Im going to attached it now for you to review if you have time..Please refer to the condition stated above... Thanks and best regards, lordgalen Attachment SAMPLE WIRING DIAGRAM.pdf (267 Downloads)

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6/7/2011 8:49 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	Well, it's standard wiring diagram, so everything i said above is true Please write MLFB number for your DI module
Aret Posts: 2348 Rating: (265)
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6/7/2011 11:41 AM	Rate (0)
Khaled_Ezzat Silver Member Joined: 9/7/2007 Last visit: 10/9/2024 Posts: 550 Rating: (62)	lordgalen Hi Aret, Thanks for the response..Another question, what if power goes through the DI module? Or an unexpected voltage coming from the MCC pass through the signal cables connected to the front connectors of that DI module?Will it break the DI module and shut down the power supply (SITOP 24 V supply)?Or will it just break the DI module and doesnt affect the power supply (SITOP 24 V supply) at all? Regards, lordgalen Hilordgalen, I faced this problem previously, I used: 1) DI module: 6ES7 321-BL00-0AA0 2) Front Connector:6ES7 392-1AM00-0AA0 3) Bus Unit:6ES7 195-7HB00-0XA0 An external short circuit happened, 380 V AC from the MCC passed through the signal cables, as a result the front connector melted!!! The DI module was destroyed because the short circuit had made a big hole in the plastic casing of the module, finally the electrical circuit inside the Bus unit was damaged and we replaced all the three items. Nothing else was damaged
	Best Regards
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6/9/2011 5:33 AM	Rate (0)
boycemento Experienced Member Joined: 4/22/2010 Last visit: 6/5/2024 Posts: 82 Rating: (1)	Thank you so much experts....

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