How To Test LV Cable

GENERAL TESTS PROCEDURES (For Low Voltage Power Cables)

CABLE RATED VOLTAGE FROM 6.6kV to 33kV

Generally, there are 2 types of tests that need to be done for each individual cable namely a) Electrical and b) Non-Electrical Test.

1) Electrical Test. (This test shall be conducted for every cable drum produced)

a) Voltage Test
Voltage shall be applied between the conductors and the metallic screen (earth) for designated duration. The voltage shall rise gradually to the testing voltage of 35Uo and kept at the testing voltage for 5 minutes. Values of single-phase test voltage for the standard rated voltages as per table below. No breakdown of insulation shall occur. [IEC 60502-1 clause 15.3].

b) Measurement of Electrical Resistance of Conductor
DC resistance of each conductor shall be measured using a suitable measuring bridge at ambient temperature and then corrected to a temperature of 20oC and 1 km length in accordance to the factor given in IEC 60228. The resistance corrected shall not exceed the appropriate maximum value specified in IEC 60228. [IEC 60502-1 clause 15.2].

c) Insulation Resistance Test
The insulation resistance test shall be made at ambient temperature. Each cable shall be measured using a 500V Insulation Resistance Measuaring Bridge between each cores (phases) and screen (earth). No breakdown of insulation shall occur.

2) Non-Electrical Test
This test shall be conducted at frequency of 10% of the number of quantity in any contract [IEC 60502-2 clause 17].

a) Measurement of thickness and / or diameter of the cable construction shall be conducted on random samples. The items measured value obtained shall not be less than the minimum value as stated in the specifications. Typical measurement done as follows:

i) Insulation thickness
ii) Metallic screen thickness and overlapping
iii) Inner and outer sheath thickness
iv) Other test specified (i.e Tensile Test for Steel Wire Armored etc)

b) Hot Set Test
Sampling and test shall be conducted in accordance with IEC 60811-2-1 clause 9 shall comply with the following specifications: