IEC 60628:1985 pdf download

IEC 60628:1985 pdf download.Gassing of insulating liquids under electrical stress and ionization.
IEC 60628 describes two procedures each using different apparatus to measure the tendency of insulating liquids to evolve or absorb gas when subjected, in cells having specific geometries, to electrical stress of sufficient intensity to cause an electric discharge through a gas phase in which a gas-oil interface is located.
The methods described in IEC 60628 are suitable for purchase specifications, general selection of insulating liquids, product development and quality assurance.
WARNING! Attention is called to national regulations associated with the use of high voltage, hydrogen and solvents.
2. General notes on the methods
2.1 These methods indicate whether insulating liquids are gas absorbing or gas evolving under the test conditions. The gassing behaviour of any one insulating liquid is primarily a function of its chemistry but changes in certain test parameters can modify the results significantly.
6.1 Clean the glass cell by first rinsing it inside and outside with 1,1,1-trichioroethane then with n-heptane. Then, refill the cell with n-heptane and scrub with a stiff brush of poiyamide fibres to remove deposits from previous test.
Insert a smaller brush into the tapered joint (G) and scrub out silicone grease, taking care that none of the grease enters the cell. Again rinse with n-heptane and blow dry with clean compressed air.
Check the painted-on silver electrode, and touch up if necessary.
6.2 Clean the hollow electrode by blowing out the capillary tube with clean compressed air, rinsing the oil off the entire electrode with 1,1,1-trichioroethane and wiping off any deposit with tissue paper.
The foil is wound around the tube with its edge terminating flush with the edge of the end plate and fixed by any convenient manner (e.g. by a suitable plastic adhesive tape).
The high voltage supply is connected to the foil by a braided copper lead with a clamp at the end.
13.1.3 Inner (earth) electrode (see Figure 5, page 32) made of free-cutting steel, precision machined and polished to the dimensions shown in Figure 5.
The centring cone protruding from the upper face of the electrode has a base of 4 mm diameter and an angle of 90’ at the tip of the cone. The tip is slightly rounded.
All edges are slightly rounded and the electrode surface free from burrs, scratches, or other flaws. The electrode shall be handled with great care and only placed on surfaces covered with filter paper.
0-rings made of suitable resistant material, 11.3 mm inside diameter and 2.4 mm thick should be used to seal the cell.
16.1 Wrap the high-voltage electrode round the outside of the glass cell and fix it with suitable adhesive tape. The electrode shall embrace the glass cell tightly and its top edge shall terminate level with the top edge of the end plate of the glass cell.
16.2 Insert the glass cell vertically in the holding device with the open end up.
16.3 Fit the connecting hose on to the gas-burette and the inner electrode and secure it with clamping rings.
Insert the capillary tube into the burette and push it through until it projects out of the mouth of the oil duct of the inner electrode and extends to the electrode.
16.4 Filter about 50 cm3 of the oil sample through a previously dried filter paper and rapidly introduce 20 cm3 of the filtered oil into the glass cell.
16.5 Carefully insert the inner electrode to the end plate of the tube in such a way that the oil slowly rises through the oil duct in the inner electrode and the connecting hose into the burette.IEC-60628-1985

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