Testing of Cables - Deepakkumar Yadav

Testing of Cables

Q. Write a note on cable sample preparation before it is subjected to various tests.

Cables play important role in transmission and distribution of electric power. The different tests on cables are tabulated in Table

Item	Test Category	Sr. No	Table to be performed
	Power frequency test	1.	Power frequency voltage
		2.	Dielectric power factor test
		3.	Dielectric break down test
		4.	Dielectric withstand test
	Insulation Resistance	5.	Megger test
Cable	Partial Discharge	6.	Partial discharge test
	Other test	7.	Thermal duty test
		8.	Life expectancy test

[Routine test : Sr. No. 1 ; Type test : Sr. No. 2,3,4,5,6 ; Special test : 7,8]

The full drum length of the cable or minimum 3m, sample piece shall constitute the test specimen
In any consignment the cables of the some size or type manufactured under ogole essentially similar conditions of production shall be grouped together to constitute a dot.
Samples shall be taken and tested from each lot for ascertaining the conformity soubor of the lot to the requirements of the specimen.
The number of samples to be selected shall depend on column 1 or 2 of the following table. These samples shall be taken at random.

Number of Drums/ Coils/ Reeds and the Lot (N)	Number of Drums/ coil/ reeds to be taken as sample (Ω)	Permissible Number of Reflectives (a)
Upto 25	3	0
26 to 50	5	0
51 to 100	8	0
101 to 300	13	1
301 and above	20	1

From each of the drum/ coils /reeds selected according to coil 1 or 2 of the above table suitable lengths of test samples shall be taken. These test samples moteur shall be subjected to each of the acceptance tests. A test sample is called defective if it fails in any one of the acceptance tests. If the number of defectives is less than or equal to the corresponding permissible number given in coil 3 of the above table, the lot shall be declared as conforming to the required of the acceptance tests; otherwise not.