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Damaging 12/24RC Logo's

Created by: seayou at: 9/18/2011 9:19 PM (5 Replies)

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9/18/2011 9:19 PM	Rate (0)
seayou Posts: 2 Rating: (0)	I have an issue where the Logo modules are being damaged. They will work for 3-5 days and then the Logo will fail. I have recorded the voltages during these failures and it is constant between 23.8 and 24.6 VDC. I have had three (3) of them fail and they will not power up at all. I have had two of them fail where the display is blank. I have had two where the input screen shows that I1 and I2 are set to 1 even though there is not an input physically connected to I1 or I2. There has also been one LOGO that all four outputs will not turn on even though the output screen shows them set to 1. Do you have any idea what can be causing this? I have checked all wiring and can not locate any short circuits. As I said above, the LOGO's will work for 3-5 days perfectly and then just fail.
seayou Posts: 2 Rating: (0)
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9/19/2011 3:58 AM	Rate (0)
derf nedraw Bronze Member Joined: 3/26/2009 Last visit: 2/3/2022 Posts: 43 Rating: (11)	What type of enviroment are the logos in?

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9/20/2011 4:03 PM	Rate (0)
MercianMatt Posts: 3 Rating: (0)	Is it possible that there is EMI resulting in supply spikes of magnitude greater than the maximum supply voltage? E.G. back EMF from relay coils? MM
MercianMatt Posts: 3 Rating: (0)
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9/21/2011 10:21 PM	Rate (0)
Williemcguire Posts: 1 Rating: (0)	Do you have DC Contactors / Relays in your control circuit? Do they have surge protection? If you dont have a Flywheel diode surge protection connected across the coils when you colapse the magnetic field this can cause high voltage to be discharged causing damage to electronic equipment connected in the control circuit> .
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9/22/2011 2:04 AM	Rate (0)
seayou Posts: 2 Rating: (0)	I appreciate your reply. The really strange part of this is that I use the Logos extensively on my equipment. I have a total of 10ea. of the 12/24 RC Logos in each control panel on probably 50 machines built over the past 5 years. I have never had a problem with a Logo other than blowing an output occasionally. This problem has gotten really bad and because the equipment is located on a bridge in Canada is costing me lots of $$$. The only components that are driven by the outputs are small pneumatic solenoids that use about 0.5 amps. The inputs are two wire 10-30vdc proximity sensors. The 24vdc supply is from two batteries which are being charged by the Cummings diesel engine. I have put a chart recorder on the supply and have not recorder any thing higher than 25.2 vdc. During the time the recorder was connected, I lost 4- more Logos. I disassembled a few of the Logo's and each one has the same component damaged. It looks like two small diodes which are traced directly to the 24vdc supply terminal. I have tried to get a schematic from Siemend to see exactly what these components are, but that appears to be unlikely that they will give me one. I'm starting to think now that the problem may be static electricity. There are no large contactors or relays on this circuit as there are no motors connected. The Logos which have the outputs driving a contactor for a motor load have never failed. Does nayone know of anything like a DC arrester that I could install directly to my 24vdc supply that would prevent (filter) static from doing the damage to the logos. Would it be possible to use a diode accross the supply of the Logo? I appreciate in advance any help or suggestions that anyone may have. Thank you
seayou Posts: 2 Rating: (0)
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9/22/2011 12:04 PM	Rate (0)
Marcjan Platinum Member Joined: 4/22/2010 Last visit: 12/13/2024 Posts: 5697 Rating: (715)	Hello, This is what the manual tells about it To suppress voltage peaks on the power supply lines, please install a protection device. DEHN (order number: 918 402) is recommended. http://www.dehn.de/ http://dehn.de/TDatenblatt2PDF/pdbpdf2?familyid=57&identnr=36701&prod=yl&artnr=918402&lang=en&pub=true Regards, Marcjan
	Last edited by: Marcjan at: 9/22/2011 12:08 PM Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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