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Mastering Cable Testing with EN 50397-1: Methods, Machines|Annex D – Resistance to UV Rays

BS EN 50397-1:2020, also known simply as EN 50397-1, is a comprehensive standard that encompasses various aspects of cable testing. It covers non-electrical tests on samples of complete cables, including resistance to UV rays, an essential factor in determining a cable’s durability, especially for outdoor applications. The standard is particularly focused on covered conductors for overhead lines, providing guidelines for testing their mechanical and electrical properties to ensure they meet the required performance standards.

In the realm of electrical engineering, Ensuring the quality and reliability of cables is paramount. Whether it’s for industrial applications, infrastructure projects, or residential wiring, Cables play a crucial role in the transmission of power and data. To guarantee their performance and longevity, Rigorous testing standards must be adhered to. One such standard that stands out is EN 50397-1, Which outlines the testing methods and requirements for covered conductors used in overhead lines and related accessories for rated voltages above 1 kV AC and not exceeding 36 kV AC.

Mastering cable testing with EN 50397-1 requires a comprehensive understanding of the standard’s requirements, Careful selection of test methods and machines, and adherence to best practices in wire, cable, and electrical component testing. By following these guidelines, Engineers can ensure the quality, reliability, and safety of electrical installations, Ultimately contributing to the success of projects and the satisfaction of stakeholders.

(b)Test Method for EN 50397-1   The samples shall follow a cycle of 5 days. During these days they shall be subjected to the following tests: Test Methods and Test Machine’s Choice:
     
Day 1 Exposure for one day to light radiation in a humid atmosphere, (relative humidity ≥ 85 %), at the temperature of (25 ± 2)°C with sprinkling; Test Machine 1: Xenon Test Chamber
Machine’s Model: WEW-080-XD|WEW-175-XD
Machine’s Source: https://www.wewontech.com/weatherometer/
Temperature Control Object: Air
Radiation Intensity:550W/M2 at 300~800nm

Program Test:
Step 1: From Room Temp change to +25℃, 85%RH in 20 minutes
Step 2:  +25℃, 85%RH with Water Spray for 3 minutes Continuous
Step 3: From Room Temp change to +25℃, 85%RH in 20 minutes
Step 2:  +25℃, 85%RH with Water Spray for 3 minutes Continuous

Total is 60 Cycles = 24 hours
The sprinkling of demineralized water lasts 3 min per period of 20 min: it is done with the aid of injectors in which the water discharge should be sufficient to ensure the washing of all the test specimens.
     
Day 2 Exposure for one day in a humid atmosphere at the temperature of (50 + 2)°C with thermal shocks obtained by being put into an enclosure kept at (-25 + 2) °C for three one-hour periods.  Test Machine 2: Environmental Chamber
Machine’s Model: TH-080|TH-150
Machine’s Source: https://www.wewontech.com/temperature-humidity-chamber/

Program Test:
Step 1: From Room Temp to +50℃, 75% in 30 minutes
Step 2: +50℃, 75% for 5 hours Continuous
Step 3: From Test Room Temp to -25℃ in 90 minutes
Step 4: -25℃ for 60 minutes

Step 5: From -25℃ to +50℃, 75% in 30 minutes in 30 minutes
Step 6: +50℃, 75% for 5 hours Continuous
Step 7: From Test Room Temp to -25℃ in 90 minutes
Step 8: -25℃ for 60 minutes

Step 9: From -25℃ to +50℃, 75% in 30 minutes in 30 minutes
Step 10: +50℃, 75% for 5 hours Continuous
Step 11: From Test Room Temp to -25℃ in 90 minutes
Step 12: -25℃ for 60 minutes

Total 12 steps = 3 Cycles = 8 Hours*3 = 24 Hours
Test Machine 2-1: Shock Test Chamber (Wewon’s Custom Design)–Optional
Features:
Shock Test Chamber with Humidity → Wewon’s Custom Design ! → Tips: Shock test with Humidity, There no supplier in the market. But Wewon Tech can do it !

Machine’s Model: TST-080
Mode of Movement: Horizontal Way
Purpose and Reson: The hot-cold or cold-hot transfers should be done in the shortest time possible !
Functions: The hot-cold or cold-hot transfers in
3~5 minutes.
Machine’s Source: https://www.wewontech.com/shipment-009/

Program Test:
Step 1: From Room Temp to +50℃, 75% in 30 minutes
Step 2: +50℃, 75% for 5 hours Continuous
Step 3: From Test Room Temp to -25℃ in
3~5 minutes
Step 4: -25℃ for 60 minutes

Step 5: From -25℃ to +50℃, 75% in 30 minutes in 30 minutes
Step 6: +50℃, 75% for 5 hours Continuous
Step 7: From Test Room Temp to -25℃ in
3~5 minutes
Step 8: -25℃ for 60 minutes

Step 9: From -25℃ to +50℃, 75% in 30 minutes in 30 minutes
Step 10: +50℃, 75% for 5 hours Continuous
Step 11: From Test Room Temp to -25℃ in
3~5 minutes
Step 12: -25℃ for 60 minutes

Total 12 steps = 3 Cycles = 8 Hours*3 = 24 Hours
The hot-cold or cold-hot transfers should be done in the shortest time possible.
The time the test specimens remain in a humid atmosphere between two thermal shocks should be one hour or more.
     
Day 3, 4 Two days exposure to light radiation in a dry atmosphere during which the temperature is kept at (70±2)°C and the relative humidity is less than 30 %; Test Machine 1: Xenon Test Chamber
Machine’s Model: WEW-080-XD|WEW-175-XD
Machine’s Source: https://www.wewontech.com/weatherometer/
Temperature Control Object: Air
Radiation Intensity:550W/M2 at 300~800nm

Program Test:
Step 1: From Room Temp change to +70℃, 30%RH in 60 minutes or sooner
Step 2:  +70℃, 30%RH without Water Spray for 47 hours

Total is 48 hours = 2 days
     
Day 5 The fifth day, Exposure for 8 h with 0,067 % in volume of sulphur dioxide and kept at a temperature of (40 + 3) ‘C with saturating humidity. For the last 16 h the door of the enclosure is left open to the laboratory environment. Test Machine 3: SO2 Corrosion Chamber | Sulfur Dioxide Corrosion Test Chamber
Machine’s Model: WEW-SO-90D|WEW-SO-120D
Machine’s Source: https://www.wewontech.com/so2-corrosion-chamber/

Step1: 8 h with 0,067 % in volume of sulphur dioxide and kept at a temperature of (40 + 3) ‘C with saturating humidity.
Step 2: For the last 16 h the door of the enclosure is left open to the laboratory environment.

Total is 24 hours = 1 day = 8 Hours + 16 Hours
During the exposures the test-pieces, Similar to those defined for the tensile test, shall be placed on supports, taking care that they are not subjected to any tensile force.
     
Test Finish and Visual Verification At the end of the test, The samples shall be removed and kept protected from direct sunlight in the laboratory atmosphere for 24 h at least. A visual verification shall then be carried out to ensure that there is no significant discolouration between the aged test pieces and those not subjected to the test.

When it comes to conducting tests according to EN 50397-1, Selecting the appropriate test methods and machines is crucial. Annex D of the standard outlines specific test methods for various properties of covered conductors, Such as insulation resistance, Bending performance, and resistance to environmental factors like UV radiation. These methods serve as a comprehensive guide for engineers and technicians tasked with conducting cable tests.

In addition to choosing the right test methods, Selecting the appropriate test machine is equally important. Test machines designed for EN 50397-1 compliance are equipped with features tailored to meet the standard’s requirements. These machines are capable of subjecting cables to various mechanical and environmental stresses, Allowing for accurate and reliable testing of their performance under different conditions.

EN 50397-1|Annex D|Non-Electrical Test on Samples of Complete Cable -Resistance to UV rays|D.1 Resistance to UV Rays a) Test Principle and Definition of the Light Source
This test is based on the prolonged exposure of the flat surface of the outer side of the cable test specimens to ultraviolet rays.
The light source used should be such that in a dry atmosphere (relative humidity below 30 %) the exposed surface of the two flat surfaces of the test specimen, the side corresponding to the outside of the test specimen cable, receives a radiation in which the wavelength-dependent energy distribution complies with the values indicated on the curve (Figure D.1).
EN 50397-1 Annex D - Resistance to UV Rays
To take account of the dispersion of the lamps and their ageing, the following tolerances are accepted:
(i)20 % in the area of ultraviolet radiation (wavelengths below 400 nm)
(ii)50 % for the visible radiation (wavelengths above 400 nm)
This radiation may be obtained with a xenon lamp fitted with quartz filters
The test requires two batches of six test-pieces; one of them being the reference batch. (c)Test Pieces
The reference batch shall be kept at ambient temperature avoiding direct sunlight throughout the environmental testing.
The other batch shall be subjected to the specified 5 days cycle and then conditioned like the reference batch for 24 h.

Cable testing plays a crucial role in ensuring the safety, Reliability, and longevity of electrical installations. By subjecting cables to rigorous testing procedures, Engineers can identify potential weaknesses or defects that could compromise their performance in real-world scenarios. Moreover, Testing helps verify compliance with industry standards and regulatory requirements, giving stakeholders confidence in the quality of the cables being used.

EN 50397-1 is just one example of the numerous standards governing the testing of wires, cables, and electrical components. These standards cover a wide range of parameters, including mechanical strength, electrical conductivity, Insulation resistance, and resistance to environmental factors. By adhering to these standards, Manufacturers can ensure that their products meet the necessary quality and safety criteria, ultimately enhancing customer satisfaction and reducing the risk of failures or accidents.

In addition to following standardized test methods, Selecting the right testing equipment is essential for accurate and reliable results. Test machines designed specifically for wire, cable, and electrical component testing are equipped with features such as precision instrumentation, Automated testing procedures, and advanced data analysis capabilities. These machines enable engineers to conduct tests efficiently and effectively, Minimizing the risk of errors or inconsistencies.

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