Standard/Testing Method: IEC 60794-1-21 E1, EN 187000 method 501, EIA/TIA-455-33, FOTP-33, IEEE 1222
Object
This measuring method applies to optical fiber cables, which are tested at particular tensile strength in order to examine the behavior of the attenuation and the fiber elongation strain as a function of the load on a cable, which may occur during installation and/or operation
Sample
The cable length under test is at least 50 meters, Additional cable length is needed to connect the fibers to be tester
Apparatus
The apparatus consists of
An attenuation measuring apparatus, typically an OTDR supplied by customer
A fiber elongation strain measuring apparatus based on dispersion testing equipment
A specially designed tensile test machine capable of tensioning cables with length at least 50 meters in six legs. The machine is equipped with a motor for controlled tensioning and a load cell for measuring the actual tension applied on the cable.
Procedure
The cable is wound in the machine over appropriately sized sheaves. The cable ends extend to reach the measuring instruments. A pre-determined number of fibers within the cable are concatenated by fusion splicing. Typically, two sets of fibers are used, one will serve to measure attenuation change and the other serves for elongation monitoring.
After all initial measurements and calibration are carried out, the cable is pulled at a specified rate until a pre-determined tension is applied. The cable is laid to rest under tension as per detail specifications, and then the attenuation and fiber length are measured.
This process may involve several tensile levels in order to characterize the entire tensile behavior of the cable, or be carried out only at the defined maximum allowed tension level.
Pass/Fail criteria
1. Under load, the fiber attenuation is not increased more than a predetermined value, typically 0.05dB over fiber length measured
2. Under load, the fiber does elongation by more than a pre-determined value over its initial length. The allowed elongation under installation load is typically 0.25%