UNE-EN IEC 60793-1-47:2018

This part of IEC 60793 establishes uniform requirements for measuring the macrobending

loss of single-mode fibres (class B) at 1 550 nm or 1 625 nm, category A1 multimode fibres at

850 nm or 1 300 nm, and category A3 and A4 multimode fibres at 650 nm, 850 nm or 1

300 nm, thereby assisting in the inspection of fibres and cables for commercial purposes.

The standard gives two methods for measuring macrobending sensitivity:

" Method A Fibre winding, pertains to class B single-mode fibres and category A1

multimode fibres.

" Method B Quarter circle bends, pertains to category A3 and A4 multimode fibres.

For both of these methods, the macrobending loss can be measured utilizing general fibre

attenuation techniques, e.g., the power monitoring technique (see Annex A) or the cut-back

technique (see Annex B).



Methods A and B are expected to produce different results if they are

applied to the same fibre. This is because the key difference between the two methods is the

deployment, including the bend radius and length of fibre that is bent. The reason for the

difference is that A3 and A4 multimode fibres are expected to be deployed in short lengths

with a smaller number of bends per unit fiber length compared to single-mode and category

A1 multimode fibres.

In the following text, the curvature radius is defined as the radius of the suitable circular

shaped support (e.g. mandrel or guiding groove on a flat surface) on which the fibre can be

bent.

In addition, informative Annex E has been added to approximate bend loss for class B single mode fibres across a broad wavelength range at various effective bends.