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BS EN 60068-2-39:2016 pdf free

BS EN 60068-2-39:2016 pdf free.Environmental testing Part 2-39: Tests一Tests and guidance: Combined temperature or temperature and humidity with low air pressure tests.
This part of IEC 60068 provides a description of test methods and guidance for testing of equipment or components under combined temperature or temperature and humidity with low air pressure tests.
The object of combined testing is to investigate to what extent the equipment or components are affected by combined temperature or temperature and humidity with low air pressure tests.
The method of combined tests detects electrical, mechanical or other physical variations.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. 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 60068-2-78, Environmental testing — Part 2-78: Tests — Test Cab: Damp heat, steady state
3 Terms and definitions
4 Testing
4.1 General
All values of test parameters such as cold, dry heat, low air pressure, humidity, exposure time and conditions such as state of operation and so on, should be selected from the IEC 60068-2 series or the relevant specificatiori
The duration of exposure shall be measured from the time when temperature stability of the specimen has been reached under conditions of low air pressure. Temperature stability shall be according to IEC 60068-1.
It should preferably be tested with low air velocity.
4.2  Preferred combinations
Preferred combinations of temperature, low air pressure and duration shall be selected from Table 1.
4.3 Initial measurement and functional performance test
The specimen shall be submitted to the visual, dimensional and functional checks specified by
the relevant specification.
4.4 Test procedure
4.4.1 Precondltloning
The relevant specification may require preconditioning of specimen.
4.4.2 Test with temperature and low air pressure
Figure 1 and Figure 2 show examples of test sequence with temperature and low air pressure.
The specimen shall be introduced in the chamber as required (unpacked, switched on or off, etc.).
The temperature within the chamber shall be adjusted to the required temperature as determined in 4.1. The rate of temperature change should not exceed 1 K!min. The specimen shall be allowed to reach temperature stability.
In the case of electrically-operated specimens, a function check shall be made in accordance with the relevant specification. Intermediate measurements shall be performed as required or specified in the relevant specification.
The pressure in the chamber shall then be reduced to the required value as determined In 4.1. The rate of change of pressure should not exceed 15 kPa/min.BS EN 60068-2-39 pdf free download.

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