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AC voltage signal affect on ETHERNET, OPTICAL FIBER cable

Created by: sunn7 at: 9/3/2009 3:00 PM (3 Replies)

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9/3/2009 3:00 PM	Rate (0)
sunn7 Posts: 152 Rating: (2)	hi all i have very small cabinet (i can say a box 30cmx30cmx20cm) where 230vac-24vdc convertor and scalance switch are located. scalance switch is connected with OPTICAL FIBER cable, and TWISTED PAIR cable. my question is Voltage convertor reciving 230Vac ups as input. as the cabinet/box is very small i want to know how it intefersoptical fiber, twisted pair ethernet cables. does it have any induction influence ?? if, what is minimum distance to be maintained between 230VAC and ethernetcables thanks in advnace sun
sunn7 Posts: 152 Rating: (2)	Last edited by: sun7 at: 9/3/2009 3:03 PM Last edited by: sun7 at: 9/3/2009 3:02 PM
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9/3/2009 4:57 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 1/21/2025 Posts: 1548 Rating: (538)	1) Optical fibre - Should have no effect as it uses light rather than electricity. However, I suppose there is a possiblity of the convertors / repeaters might be affected. 2) Ethernet - Could potentially be affected as it uses electrical signals. The signals are +/- 48V differential voltage (balanced line). The ammount interference would depend on the proximity of the mains cable and the standard of cable used for the ethernet connection (screened / unscreen etc.). 3) Twisted Pair - Not sure what you mean by twisted pair. This is just the cable type. The susceptibility to interference would depend on what driver you are using (RS232, RS485 etc.). RS232 is very susceptible to interference as it uses +/-12V signal levels referenced to a common ground. RS485 / RS422 is less susceptible as the signals are +/-9V differential voltage. Again as with the Ethernet case, the standard of cable and AC proximity are the important factors. All of the above is theory. In practice, the likehood of you having problems is minimal. I have used quite small cabinets and never had any issues. Just take some simple precautions as routing signal cables away from power cables / solenoid control cables and use good quality screened cable with the screen terminated at one end only (don't terminate at both ends as that can cause earth loops).
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9/3/2009 5:02 PM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Sun, please consider in this point the regulations explained in chapter 7 of the manual: SIMATIC NET Twisted-Pair and Fiber-Optic Networks Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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This contribution was helpful to 1 thankful Users sunn7

9/9/2009 9:36 AM	Rate (0)
sunn7 Posts: 152 Rating: (2)	hello smiffy thank you. i took small precautions and it is fine. By TWISTED pair , I mean, ETHERNET twisted pair cable cheers sun
sunn7 Posts: 152 Rating: (2)
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