Sometimes the cables have to be laid in the area of low temperature climatic condition or frost. Due to constant exposure of cables to low temperature or frost conditions, the insulation or sheath of the cables becomes hard and brittle. Any impact on the surface of the sheath or cable under these conditions may fracture the insulation, thus making it weak or causing it to fail.
The suitability of the insulation material against low temperature brittleness is determined with the help of an impact test conducted on the cable maintained at a specified low temperature. In this test, the cooled cable is placed on an anvil inside a cold chamber and an indentor dropped on its upper surface to give it a specified impact. The effect of impact is then checked to evaluate the quality of the cable insulation.
The Cold Impact Tester for cables consists of a rigid steel frame having a solid steel anvil and a support to hold an aluminium pipe, and an indentor, which can be dropped vertically from a specified height on to the top of the cable. The test is carried out at a specified sub-zero temperature inside a deep freezer.
IS 10810 (Part 21) - 1984 : Methods of Test for Cables
Part 21 : Cold Impact Test.