- Type Tests Definition: Type tests ensure the quality and standards of electrical power cables by assessing various physical and electrical properties.
- Acceptance Tests: Acceptance tests verify that a batch of cables meets the required specifications through mechanical and electrical tests.
- Routine Tests: Routine tests are regular checks to maintain consistent quality and performance of electrical cables.
- High Voltage Test: This test involves applying high voltage to the cable to ensure its insulation can withstand extreme conditions.
- Cable Testing Importance: Cable testing is crucial for ensuring the safety, reliability, and longevity of electrical power systems.
- Type tests prove a cable design before regular supply. The following type tests apply to an electrical power cable.
- Persulphate test (for copper )
- Annealing test (for copper)
- Tensile test (for Aluminium)
- Wrapping test (for Aluminium)
- Conductor resistance test (for all)
- Test for thickness of insulation (for all)
- Measurement of overall diameter (where specified)(for all)
Physical tests for insulation and sheath sit in that type-test group.
- Tensile strength and elongation at break
- Aging in an air oven
- Aging in air bomb
- Aging in an oxygen bomb
- Hot set
- Oil resistance
- Tear resistance
- Acceptance tests check a delivered lot. The following shall constitute the acceptance tests:
- Annealing test (for copper)
- Tensile test (for Aluminium )
- Wrapping test (for Aluminium )
- Conductor resistance test
- Test for the thickness of insulation and sheath and overall diameter
- Tensile strength and elongation at break of insulation and sheath
- Hot set test for insulation and sheath
- High voltage test
- Insulation resistance test
- Routine tests run on every finished length. The following shall constitute the routine tests.
- Conductor resistance test
- High voltage test
- Insulation resistance test
High Voltage Test (Water Immersion Test) :
Type, acceptance and routine tests are the three factory groups. For the water-immersion type test, IS 1554-1 takes about 3 m of core from the finished cable or cord. The core sits in a water bath with the ends at least 200 mm above the water. General-purpose PVC uses a 60 C bath, not room temperature; heat-resisting PVC uses 70 C. After 24 hours an alternating voltage is applied between the conductor and the water. The voltage is raised to the product-standard value within 10 seconds and held for 5 minutes. IS 1554-1 for 1.1 kV PVC raises 3 kV to 6 kV AC. If the sample fails, one more sample is tested and that repeat must pass.
Test on completed cables (Acceptance and routine test) :
These tests are applied between conductors or between conductor and screen or armour. IS 1554-1 calls for 3 kV AC or 7.2 kV DC at room temperature for 5 minutes on each connection, with no breakdown. Other grades use the voltage in their own product standard.
Flammability Test :
IS 1554-1 and IS 10810-53: after the flame is removed, burning shall not last more than 60 s and the uncharred length from the lower edge of the top clamp shall be at least 50 mm. IEC 60332-1 uses a different flame and pass rule, so do not treat this as that test.
