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jsummerfield (Electrical) (OP)
10 Mar 03 22:52
On an offshore platform, we have a run that is about 110 meter to connect a various PLC equipment in a machinery area with a master workstation and assorted items in another area.  The communication exists with copper cable running 10 MHz Ethernet.  We would prefer to run 100 MHz.  However, large motor and generator switchgear equipment exists on the machinery end.  The technicians had some difficulty with the communication at 10 MHz.  This will carry control communication between industrial control systems and requires reliability.  The interconnectin will be between Ethernet switches.

Before we begin running this equipment, I decided that fiber optical cable would eliminate the electrical noise issue and improve the distance issue.  I know about nothing about fiber optical cable.  I intend to use the existing conduit that connects the areas for the fiber optical cable.  I need some input about the cable selection and issues such as pulling tension and bending radius in conduit.  I have read that the appropriate communication method would be single mode using 62.5 micron.

I am interested in a recommendation for the appropriate cable and accessories for this application.  Presumably the Ethernet switches will have about 12 RJ style Ethernet connectors and a fiber optical connector.  I need to know something about the connectors, the cable diameter, pulling strength and bending radius to determine if we can use existing or replace conduit, etc.  Also I need to buy the gear.

Comments??

John
Helpful Member!  robertjo24 (Industrial)
11 Mar 03 7:38
My first question would be why single mode over multimode fiber? If you are only going 110M, then multimode is the best bet, (rated up to 2KM). It is cheaper to buy and install, and the associated end equipment and jumpers will be cheaper.
As for conduit, each manufacturer will list the specs on their cable. I would call an electrical supplier in the area (on shore) and request the specs on a multi-strand multimode fiber. You can also visit http://bwccat.belden.com, and get some info there on different fiber cables and bend radius. They have a contact number on the site as well. An electrician I spoke with, recommended a long bed radius on the conduit (12”-24” min for multi-strand fiber cable), and no sharp transitions like found in a standard “LB” fitting. There are fiber cable made for harsh environments, with a messenger wire built onto the cable. Can you run the cable outside of conduit in a tray?
The two most common connectors on LAN equipment will be “ST” or “SC” type, see http://www.fiberoptics4sale.com/fiber-optics-connectors.asp?source=overture&keyword=fiber-connector for more info. I think that the “ST” type might work best in the corrosive atmosphere of an offshore platform.
As for the switches, try www.alliedtelesyn.com, they have some good equipment, priced right. Also look at www.netgear.com. For lower cost devices, I have found these two the most reliable. You could use a standard copper switch, and use a media converter, (copper to fiber), to change over to the fiber cable. If you want a higher end switch, you can go with someone like Cisco. You can get a used switched with multimode interfaces for a pretty good price. EBAY is a great place to look for used equipment. I would buy from a reseller to ensure you get some sort of warranty. One word of caution on used equipment, sometimes there may still be passwords set on the devices, so make sure you find some documentation to show you how to get around the password. Cisco has online documentation on how to get into their switches if the passwords are set and you do not know them.
I hope this helps.
tomatge (Industrial)
11 Mar 03 12:53
Robertjo24 has given you a lot of good information, to which I'll add a couple of comments.

I agree that multimode fibre should be more than adequate for 110m at 100MHz, and termination equipment will be cheaper. By the way 62.5micron is multimode (singlemode is 9micron). In terms of transmission, you can get switches/hubs etc. with fibre connectivity, most major manufacturers will have something in their range. If you already have equipment with only electrical ports, you can by media convertors or repeaters from somewhere like Black Box will will allow you to cheaply use existing equipment.

Industrial fibre cables will usually have GRP or Kevlar central members for which you will get good pulling tension capability. Bear in mind that in commercial telecommunications applications, they may pull cables over 2km in buried subducts (albeit smooth bore ducts, with plenty lubricant). Nonetheless, I wouldn't expect you'll have problem over 110m. Regarding bend radii, if you can install power/multicore cables (presumably armoured) through your ducts, you'll be OK with fibre.
ragudelo (Computer)
17 Mar 03 10:11
Agree about multimode fiber, the standard multimode is 62.5/125, and you must make sure you buy the right connectors for it. Better hire a certified FO installer, since making the connectors is not a piece of cake.

What I would rather suggest is try to avoid getting  material from different providers, if you are not used to do so and understand very well what you're doing. The best I can suggest in providing most materials you would need is Phoenix Contact. Had used them for years, a bit pricy, but rugged and very reliable, and aimed to Industrial Automation. You can check about them at: http://www.ethernetrail.com/
You better forget about hardcore IT stuff, like Cisco line, since they are not build to endure the rugged conditions of industrial applications, they don't behave very well in environments with heavy vibration.

One word of warning, as the application is in an offshore platform, I would suggest make sure the FO cable is sealed tight (don't know if jelly-filled cable would be the right seal) and will not allow the migration of gases in it.

RA
resqcapt19 (Electrical)
21 Mar 03 9:57
Standard conduit bends are almost always suitable for use with fiber cables as the standard conduit bending radius is larger than the mimimum permitted fiber bending radius.  The problem that you may have is at conduit fittings such as LBs and Ts, as in most cases, there in not enough room to meet the minimum bending radius of the fiber.  
Don
robertjo24 (Industrial)
21 Mar 03 21:31
Yes, as resqcap19 states above, the conduit bends are not the problem. There are very few conduit fittings I have seen that are suitable for medium to large capacity fiber cables. Instead of a standard "LB" or "T", it may be best to use a larger "pull box" at junctions, and pre-formed bends at entrances and transitions where a standard conduit fitting would otherwise be utilized.
Fiber is not too difficult, if you follow the general guidelines and recommendations from the manufacturer.

new2hvac (Mechanical)
13 May 03 10:15
If your conduit is large enough, you can possibly go with a pre-connectorized cable.  I suspect it would be cheaper than hiring a contractor to install on an offshore platform.

As a rule of thumb, the minimum bending radius for the cable is about 10 times the outside diameter of the cable.  This is for structural integrity of the cable.  There is another (much smaller) minimum bending radius that will cause excess attenuation in the fiber that should not be an issue if the cable remains structurally intact.

Other things to think about:
Any fire rating requirements on the cable?  Will it be exposed to water?  Oil?  There are various cable types that will be suitable for any of these applications.

In a previous life, I used to work for Corning.  Here's a phone number for Corning Cable Systems that should provide some good info:  1-800-743-2671.  Ask for the duty engineer.  You'll probably have to purchase through a distributor like Anixter or Graybar.  May be better pricing from other manufacturers - fiber is pretty much a commidity these days.

Hope that helps...
woodeneye (Electrical)
15 Jun 03 20:53
Don't know if it's to late for your project (March 11 question) but consider 50 micron fiber instead of 62.5u.  The cost of cable, connection hardware and active comm gear is no different then its larger 62.5u partner.  The advantage is that you'll get more useful life (bandwidth growth) from this product.  Cornings 300/300 series 50u will allow 10gig applicatons to 300 meters.  Consider paying the same for more.

Also, consider hiring a licenced, insured professional to see it through for you. An RCDD or PE with experience in industrial automation in the coastal oil industry could hit the ground running for you.  You'll always look good and be amazed at what you didn't realize.  This might not be a place to save money by substituting marketing/sales experience instead of genuine wisdom.

Best of luck.

pfry (Computer)
12 Sep 03 15:19
You might look at using Belden DataTuff Cat5. It's armored/shielded and cost about $650 per thousand ft.
You may be able to run it in your cable tray.
I use it at my facility in the process areas for phone/data.
Your distance(110m) is at the theoretical limit of ethernet over utp but I've pushed it farther many times.
pfry
jsummerfield (Electrical) (OP)
17 Dec 03 20:28
We installed the Ethernet and fiber optical converters.  They work just fine.  Electrical noise is a problem within the switchgear room.  There is a high gausian field affecting a desktop CRT in the room.  With the electrical noise I would be concerned about wireless.  However, wireless could be an excellent consideration for my next similar application.

John

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