Low-Temperature Mechanical Behaviour of Cable Materials
Polymer insulation and sheath materials may become harder and less flexible as temperature decreases.
For cables used in cold environments, insufficient low-temperature flexibility may lead to:
Material cracking
Reduced installation flexibility
Mechanical damage during handling
Reduced long-term reliability
Cold elongation testing provides a direct evaluation of how cable materials respond to tensile stress at low temperatures.
Test Principle
Cold elongation testing evaluates the stretching capability of insulation or sheath materials after exposure to a specified low temperature.
Unlike cold bend testing, which evaluates bending resistance, this method measures the elongation performance of the material itself under tensile force.
The test is performed according to IEC 60811-505, which specifies the procedure for determining elongation at low temperature for extruded insulation and sheath materials.
Test Procedure
Specimen Preparation
Samples are prepared from the cable insulation or sheath material.
The material is cut into standardized test specimens suitable for tensile measurement.
For larger cable constructions, dumbbell-shaped specimens may be prepared from the insulation or sheath layer according to the applicable procedure.
Low-Temperature Conditioning
Prepared specimens are placed inside a controlled low-temperature chamber.
The samples are conditioned until the required test temperature is reached and the material reaches a stable low-temperature state.
Tensile Elongation Measurement
After conditioning, the specimen is mounted in a tensile testing device.
The grips pull the specimen in opposite directions at a controlled speed until the material reaches the point of rupture.
The elongation value is calculated by measuring the increase in length before breaking.
Evaluation of Cold Elongation Performance
The main parameter evaluated is:
Elongation at Break
The percentage increase in specimen length before rupture under low-temperature conditions.
A higher elongation value indicates better flexibility and resistance to brittle failure at low temperature.
The measured result is compared with the acceptance requirement specified by the applicable cable standard.
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