FIBER OPTIC CABLE SIGNAL TRANSMISSION

[tszpun]

Hello Experts,

I have very little knowledge about the FO cables. Could you clarify me the following :

I have 2 IEDs that will be connected via fiber optics.
And i have several signals to transmit through this fiber optic cable, such as : CB OPEN, CB CLOSED, ES OPEN, ES CLOSED.
I do not know, how many cores of fiber optic cables i should use.
If it was copper cable, i would consider 9 core cables (2 core per signal).
However, should i consider 1 core for 1 signal ? Meaning that, should i consider 4 core Fiber Optic cables ? Or is it possible to use only 1 core for all these 4 cables?

Thank you for clarification.

 

[djs]

FO cables are high bandwidth - high cost. Usually used in digital signal transmission (Ethernet or something similar). In that case you would need a remote I/O at the signal source and a poller at the end which you want the signals to arrive. Usually two fibers are used, one for transmit and the other for receive.

 

[waross]

First select your transmitting and receiving devices. You will probably use a modulator and demodulator and send multiple signals per fibre.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[davidbeach]

Very basic relays can transmit 8 digital points over a single serial connection using a pair of fibers.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[bacon4life]

Relay vendors usually offer a selection of pre-terminated fiber cables that plug directly into the back of the relay. An example is

https://selinc.com/products/C807/.

If your relay only includes RS232/485 ports, an example of the modulator/demodulator Waross mentioned is the

https://selinc.com/products/C805/.

The vendor reps can help you select the best cable option, and then have the cable manufacturer to your specific length needs.

 

[tszpun]

Very basic relays can transmit 8 digital points over a single serial connection using a pair of fibers.

Could you elaborate more on your statement?
how i can be sure that my relay is compatible ?
I am using SIPROTEC 5, could you give more explanation where i can check this information on relay manual ?

 

[cranky108]

I know SEL relays can transmit 8 bits, but other manufacturers are likely to have there own protocol.
There is no universal, just different protocols, usually different for each manufacturer.

 

[crshears]

There's nothing electrical about this thread . . .

. . . but I suppose I can understand you posting this question here, as I don't see a more suitable forum, like one for high-speed digital or fibre optic communication . . . should there be one???

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[FreddyNurk]

For this application I'd use something like this, it's purpose built for such applications, and only needs two cores.
Importantly, it also complies with the relevant protection standards, assuming from your context that this is a protection application.

EDMS Australia

 

[bacon4life]

crshears-I think this is the right forum. This question is highly specific to how fiber is used for communications between protective relays in T&D a application.

The primary reason for using fiber is often immunity to electrical noise, rather than data speed. In many cases the fiber is only "high speed" relative to old analog modems. Often the fiber converter dongles are connected to RS232 serial ports operating at the slow speed of 19200 bps.

 

[cranky108]

Might want to be concerned about fiber path relative to the electrical element you are protecting. i.e. if this is a fiber on the pole line that you are protecting, the same event might take out both assets at the same time.

 

[huskyeng]

If something takes out the OPGW and the line the remote end breakers would get tripped and reclosing should be disabled with loss of comms.

 

[DiscoP]

You may find there is "Remote Indication" signalling in the Siprotec relays (depending on the model).

If the IED is for feeder differential protection, then the fiber core being used for this protection can also be used to signal CB status etc.

There is quite a few additional signals in that relay for these types of functions (24 generic ones I think), and what you are proposing is a reasonably common application.