IEC 61300-2-21:2009 determines the resistance of a fibre optic device to the deteriorative effects of high temperature, humidity and cold conditions. It is intended to reveal defects in a device under test (DUT) caused by breathing as opposed to absorption of moisture. The test covers the effect of the freezing of trapped water in cracks and fissures as well as condensation. However, the degree of condensation will vary depending on the size and thermal mass of the DUT. The changes with respect to the previous edition are:
- to reconsider the whole parts of the standard,
- to describe the apparatus and procedure in greater details,
- to define with precision the number of 24 cycles in the severity.