IEC 60814:1997 pdf download – lnsulating liquids – Oil-impregnated paperand pressboard- Determination of water by automatic coulometric Karl Fischer titration

IEC 60814:1997 pdf download – lnsulating liquids – Oil-impregnated paperand pressboard- Determination of water by automatic coulometric Karl Fischer titration.
IEC 60814 describes methods for the determination of water in insulating liquids and in oil-impregnated cellulosic insulation with coulometrically generated Karl Fischer reagent.
The method in clause 2 is app’icable to water concentrations above 2 mikg in liquids having viscosity of less than 100 mm /s at 40 C.
The test method in clause 3, where water is extracted by means of a nitrogen stream, is the preferred method for insulating liquids of viscosity higher than 100 mmIs,
Clause 4 describes methods for the determination of water content in oil-impregnated paper and pressboard over the range 0.1 % to 20 % by mass.
1.2 Norniative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All normative documents are subiect to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60475: 1974. Method of sampling lquld dielectrics
IEC 60567: 1992. Guide for the sampling of gases and of oil from oil-filled electrical equipment and for the analysis a! free and dissolved gases
ISO 595-1: 1996, Reusable all-glass or metal-and-glass syringes for medical use — Part I Drnensons
ISO 595-2: 1987. Reusable all-glass or metal-arid-glass syringes for medical use — Part 2:
Design. performance requirements and tests
2 DIrect titration for low viscosity liquids
21 Field of application
This method is applicable to water concentrations above 2 mgikg In liquids having viscosity up to 100 mm2/s at 40 C. The precision data given in 2.10 apply only to new liquids.
2.3 Apparatus
2.3.1 Principle of operation
The titration vessel has the configuration of an electrolysis cell with two compartments connected by a porous diaphragm. The anodic compartment contains tle mixture of reagent- solvent and sample (anodic solution), the cathodic compartment (generator assembly) contains anhydrous reagent (cathodic solution). On both sides of the diaphragm are located the electrolysis electrodes.
NOTE – Titratora wflhout th. po.ous .aØIragm may b. u.d
Iodine generated by the electrolysis, as shown in reaction (3), reacts with the water in a similar way to the Karl Fischer reactions (I) and (2). The end-point of the reaction Is detected by a pair of platinum electrodes immersed in the anodic solution. At the end of the titralion, excess iodine depolarizes the dual platinum electrodes, giving a change in the current/voltage ratio which is used to activate the end-point indicator and to stop the current integrator.
The current Integrator Integrates the current consumed during the electrolysis, calculates the water equivalent according to Faraday’s law, and tinally displays it in micrograms of water.
2.3.2 Description of the apparatus
Commercial coulometric Karl Fischer litralors use proprietary circuitry. The following description of one suitable form of apparatus is given for illustrative purposes only.
The block diagram shown in figure 1 illustrates the apparatus and includes the components detailed below.