IEC 60068-2-5:2010 pdf Environmental testing – Part 2-5: Tests – Test Sa: Simulated solar radiation at ground level and guidance for solar radiation testing

IEC 60068-2-5:2010 pdf Environmental testing – Part 2-5: Tests – Test Sa: Simulated solar radiation at ground level and guidance for solar radiation testing
1 Scope and object
This part of IEC 60068 provides guidance for testing equipment or components under solar
radiation conditions.
The purpose of testing is to investigate to what extent the equipment or components are
affected by solar radiation.
The method of combined tests detects electrical, mechanical or other physical variations.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60068-1 , Environmental testing – Part 1: General and guidance
IEC 60068-2-1 , Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state
CIE 85:1 985, Solar spectral irradiance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60068-1 , as well as
the following, apply.
3.1 air mass
path length that light from a celestial object takes through the earth’s atmosphere relative to
the length at the zenith where air mass = 1 at the zenith
NOTE The air mass is 1 /sin (gamma), where gamma is the elevation angle of the sun.
3.2 black standard temperature
BST
characteristic value of the specimen surface temperature
NOTE Black standard temperature as measured by a black standard thermometer (see ISO 4892-1 ).
3.3 black panel temperature
characteristic value of the specimen surface temperature
NOTE Black panel temperature as measured by a black panel thermometer (see ISO 4892-1 ).
3.4 solar constant
rate at which solar energy, at all wavelengths, is received per unit area at the top level of
earth’s atmosphere
NOTE The value of the solar constant is E 0 = 1 367 W/m 2 .
3.5 optical depth
measure of how much light is absorbed in travelling through a medium
NOTE A completely transparent medium has an optical depth of zero.
4 General remarks
4.1 Overview
The effect of radiation on the specimen will depend on the level of irradiance, the spectral
distribution, the location, the time of day and the sensitivity of the material of the specimen.
4.2 Irradiance
The irradiance by the sun on a plane perpendicular to the incident radiation outside the earth’s
atmosphere at the mean earth-sun distance is known as the solar constant E 0 .
The irradiance at the surface of the earth is influenced by the solar constant and the
attenuation and scattering of radiation in the atmosphere. For test purposes, CIE 85 gives a
value of 1 1 20 W/m 2 for the global radiation at the surface of the earth from sun at zenith;
value based on a solar constant E 0 = 1 367 W/m 2 .
4.3 Spectral distribution
The standard spectral distribution of the global radiation specified for this test, in accordance
with the recommendations of the CIE 85, is given in Figure 1 and in Table 1 .
If the source of radiation used for the test does not meet the standard spectral distribution
given in Table 1 , the exact spectral absorption data of the material and the exact spectral
irradiance of the alternative radiation source in the range from 300 nm to about 3 000 nm and
for the solid angle of 2π sr above the specimen surface shall be known or measured.
5 Conditioning
5.1 General
During the entire test, the irradiation, the temperature within the chamber, the humidity and any
other specified environmental conditions shall be maintained at the levels appropriate to the
particular test procedure specified in the relevant specification. The relevant specification shall
state which preconditioning requirements are to be applied.
5.2 Temperature
The temperature within the chamber during irradiation and darkness periods shall be controlled
in accordance with the procedure (A, B or C) specified. During irradiation, the temperature within the chamber shall rise or fall by 1 K/min and be maintained at one of the preferred
values given in IEC 60068-2-1 , IEC 60068-2-2 or the relevant specification.
NOTE Additionally, a black standard thermometer can be used to control the maximum surface temperature. By ventilation, this temperature can be influenced.