Example 10: Tested, light in the cold

Light in the cold – igus® gradient fiber glass cable in the deep freeze test

For safely transmitting large amounts of data via bus systems at high speeds over long distances, the Chainflex® CFLG.G fiber-optic cable has already become a standard – for example, in crane applications. This is due to its insensitivity to electro-magnetic loads and resistance to potentially problematic environmental factors.

What happens with cables on cranes in extremely cold climates? Is the normal maximum cable length (a few thousand feet) reduced through increased dampening at low temperatures? Does the cable break in extreme applications, for example at -40° F? Sensitive glass fibers are conducted in a gel-filled hollow space. How does the gel behave in highly dynamic conditions? What happens in restarts after long downtimes?

As no statements on this topic could be found in any relevant technical journals - and as little was known about the thermal features of the gel - igus®, as part of its company philosophy, undertook its own tests to determine reliable specifications for cable applications in cable carriers.

For this task, the igus® test laboratory was equipped with a freezer that can generate constant temperatures of -40° F and a test facility installed inside for long travels up to 23 ft, speeds up to 5.3 ft/s, and accelerations up to 19.7 ft/s².

The igus® gradient fiberglass cable, CFLG.6G, was tested in this set-up. The cable was tested with a length of about 50 ft inside an igus® Energy Chain® cable carrier (series 3500.125.200.0, with a radius of 7.9 inches).

Varied and extreme temperature curves simulated environmental influences, sometimes plunging rapidly during downtimes from plus degree temperatures to -40° F, with the test re-started immediately afterward.

Under these application conditions, the dampening of the cable was monitored to ensure it did not rise above 3 dB at 850 nm wave length. Maximum dampening – which was still under 3dB - happened after a million cycles, corresponding to an operational performance of over 4,300 miles.

The measurements highlighted in the diagram reveal that marked variations in temperature combined with the constant movement of the Energy Chain® cable carrier have only minor effects on the dampening of the CFLG.6G. The noticeably high initial dampening can be attributed to the plugs used and also reflects real-life conditions: in practice, 90% of cables used in automation are plug-in fiber-optic cables.

The test with this igus® cable reiterates that only realistic tests can provide true insight into the service life of cables.