Information About Fiber Patch Cord Testing, Cleaning & Handling

As fiber optic technology develops and more demands are being placed on data transfer, the needs for higher bandwidth and more connections are also growing accordingly, which makes the use of fiber optic patch cables and transceivers even more important in data transmission. As one of the basic component in optical communication, fiber patch cord consists of a fiber optic cable (single-mode or multi-mode) terminated on both ends with single type or hybrid connector, like SC SC fiber cable, fiber cable LC to LC, LC-SC multimode fiber patch cord, LC ST patch cable, etc.. Patch cords are used to connect communication equipment to the cable plant or for interconnections, and their performance matters in the whole fiber optic network. As such, the proper testing of patch cords is essential in ensuring their quality, so as to avoid network problem.

Patch Cord Testing

Here goes to the first topic: patch cord testing. After terminating the fiber optic cable with connectors, it’s imperative to test both the connectors’ loss and the fiber loss in the cable. On very short cable assemblies (up to 10 meter long), the loss of the connectors will be the only relevant loss, while fiber will cause the overall losses in longer cable assemblies.

• Testing Process

In testing patch cord, what’s required is the 1310nm LED light source for single-mode fiber (SMF) and 850nm for multi-mdoe fiber (MMF), a fiber optic power meter and some reference patch cords. Use one reference patch cord to set a 0dB reference. Connect a to-be-tested patch cord to the reference patch cord with a mating adapter. Connect the power meter to the other end of the patch cord and measure the loss. Since the length of the fiber is short, the loss contribution of the fiber can be ignored.

Because one end of the cable is attached to the power meter, not another cable, only the loss of the one connection is measured between the reference cable and the cable under test, so each connector should be tested individually. Reverse the patch cord you are testing to check the connector on the other end.

If the equipment has different connectors from the patch cords you are testing, you will need hybrid reference cables with connectors compatible with the equipment on one end and the patch cord connector on the other end. You will also need the correct connector adapters for your power meter. Certainly, all reference cables used for testing must have high quality connectors to get reliable test results.

Patch Cord Cleaning

Whether newly-branded patch cords, or used patch cords, they all encounter an issue—cleanliness. All connectors should always have the polished ferrule covered by a “dust cap” to protect the end of the connector ferrule from damage and dirt. Before inserting connectors in mating adapters or active devices, it’s recommended to clean connectors.

Cleaning Process

Multiple ways are available to clean fiber optic cables and connectors. Here just list a few useful tips.

• Blow the fiber surface with a stream of Clean Dry Air (CDA) as to dislodge larger, loose particles;

• Place 1-3 drops of spectroscopic grade methanol or isopropyl alcohol in the center of a lens tissue;

• Hold the fiber by the connector or cable. Place the wet portion of the lens tissue on the optical surface and slowly drag it across;

• Examine the surface of the fiber under high intensity light using a magnifier, an optical loop, or a video inspection tool. If streaks or contaminants still remain, repeat the process using a fresh lens tissue;

• Immediately install a protective cover over the end of the cable to avoid re-contamination or insert the fiber for immediate use.

Patch Cord Handling

Some users buy large bulks of patch cords and store them in boxes until they are needed to be plugged in. Some users hang them on the sides of the equipment racks. That's not how they should be handled. It seems to be a commonplace that fiber patch cords are always subject to poor treatment (just as the image below shows). They are often hung off communications equipment or patch panels stressing the fiber at the back of the connector. When they are too long, they are bundled and hung in large piles on the side of equipment racks. Kinking is always a problem. Ideally, patch cords should be the right length, supported below the connection and carefully placed to prevent stress.

• Handling Tips

It’s ill-advised to bend the fiber patch cords. Bending the cords may cause internal breaks along the fiber resulting in poor performance or instability. Pay attention to the bend radius of the patch cable. Generally, for 1.6mm and 3.0mm cords the minimum un-loaded bend radius is 3.5 cm. In addition, it’s not allowed to pull or stress the patch cords. During the patching process, excessive force can stress fiber patch cables and connectors, thus reducing their performance.

Summary

As far as fiber patch cord is concerned, three aspects come to the point: testing closely related to quality, cleanliness, and handling. Once they are properly tested, then their quality is assured. If they are handled in right ways, and kept clean, the fiber optic network with high performance is half-succeeded. As fiber patch cord manufacturer, Fiberstore supplies many kinds of patch cords of high quality, available in single/mode and simplex/duplex version, including the above-mentioned fiber cable LC to LC, LC-SC multimode fiber patch cord. For more information about fiber optic patch cables, you can visit Fiberstore.