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IS 10810 Part28 Water Absorption Test

I. Scope - Covers a method for measurement of water absorption by elastomeric insulation of

electric cables.

!. Significance - Whenever the insutated cores are exposed to water/moisture, there is possibi- ity of absorbing of the same by *the insu~lants thereby deteriorating the electrical parameters. The

degree of water absorbed will de!pend on the quantity as well as the quality of the various ingre- lients used for compounding of elastomers. Water absorption tests will Indicate the quality of the :ompound used and also its suitatbility for critical application areas.

L Terminology - When insulated cores are kept immersed in water, the capacit:ance values of he same are changed due to abs#orption of wafer. The degrees of water absorptton is measured by 'ecording the increase in capacitance from 11 to 14 days and from 7 to 14 days w~hich are expressed PS percentage of the one day ancl the seven days values resp&ively.

1. Apparatus

1.1 Water Tank -with heating anrangement.

1.2 Suitable Bridge - for measurlement of capacitance.

1.3 High Voltage Source - 50 Hz. 1.4 Insulated Mats i Material-Water.

6. lest Specimen -A sample of the core #about 5 m long is taken after vulcanization, but before ihe application of any covering except tape applied before vulcanization. Wherever p_ossible, such iape is removed before the test.

7. Conditioning - The test specimen is prepared from the sample not less than 48 h after

rulcanization by dryin~g it for 24 f 1 h in air at 70 f 5°C. The specimen is allowed to cool to 50 f 2°C before immersion in wader.

B. Procedure

B.l The test specimen is accommodated in al water tank so that its middle portion for a length of 3 m

is immersed whilst the ends are above the water level, each for a length of 0.75 m. Tap water is used, the temperature of which is [maintained at 50 f 2°C for 14 days. A tightly fitting cover is placed directly above the water surface wifh suitab~le water tight bushings for the ends of the specimen. The water level is kept constant.

8.2 The test is carried out with the average stress as specified in individual specification.

B.3 The capacitance is measured after 1, 7 and 14 days' continuous immersion, with the water at same temperature for all measurqments.

0. Tabulation ~of Observations

Sample No. No. of days Water

TernLie t we

Testing

Stress V/mm

Capa$ance c-----~---_-~

1 Day 7 Days 14 Days

10. -Calculation

10.1 Percentage increase

1 to 14 days

Percentage increase

7 to 14 days

where

in capacitance for

e= C:r--Cl x ,()()

Cl in capacitance for

c _G?+ j( 100

C1 = the capacitance value after 1 day ( after 24 h )

C, = the capacitance value after 7 days ( after 168 h )

Cla= the capacitance value after 14 days ( after 336 h )

11. Report

11.1

11.2

Water Absorption Test of Elastomeric Insulation

Cable Type

Batch No./Lot No.

Cable No./Drum No.

Date of Testing

Results

Reference specification

Sample No. Percentage Increase in Capacitance

'-__--'---L

1 to 14 days 7 to 14 da;

__-_-__-_, t--_---*

Observed Specified Observed Specified

11.3 Conclusion - The specimen meets/doss not meet the requirements of the specification.

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