IEC 60464-2:2001 pdf download – Varnishes used for electrical insulation – Part 2: Methods of test.
5.1 Flashpoint For flashpoint temperatures of 79 °C and above, the method given in ISO 2592 shall be used. For flashpoint temperatures below 79 °C, the method given in ISO 1 523 shall be used with any of the closed-cup apparatus as described in annex A of that standard. ISO 1 523 shall be read in conjunction with ISO 3679. Two measurements shall be made on two separate samples and the two results of flashpoint shall be reported. 5.2 Density The method given in ISO 281 1 shall be used. Two measurements shall be made and the two results of density shall be reported. 5.3 Viscosity The viscosity shall be determined with a suitable device at (23 ± 0,5) °C. If a rotating type of device is used, it shall be in accordance with ISO 2555 (Brookfield type) or with ISO 321 9 (a type working at defined shear rate). If an efflux type of equipment is used, the method of test and the flow cup shall be in accordance with ISO 2431 . Two measurements shall be made and the two results of viscosity shall be reported. 5.4 Content of non-volatile matter The method given in ISO 3251 shall be used. Two measurements shall be made and the two results of the content of non-volatile matter shall be reported.
5.5 Dilution ability Dilution ability is expressed by the amount of solvent and/or diluent which can be added to the varnish until cloudiness or separation is observed. 5.5.1 Procedure A varnish sample of (50 ± 1 ) ml shall be poured into a glass cylinder of about 250 ml volume. Solvent and/or diluent as agreed between supplier and purchaser shall be added in defined portions of for instance (1 0 ± 0,2) ml until cloudiness or separation is observed. After each addition, the content of the glass cylinder shall be properly stirred to obtain a homogeneous mixture and shall be allowed to settle for at least 5 min and not more than 1 0 min. 5.5.2 Result One measurement shall be made and the type of solvent and/or diluent and the percentage in volume added without appearance of cloudiness or separation shall be reported. 5.6 Stability of varnish in an open vessel Stability in an open vessel is expressed by the change in viscosity after storing the varnish at (50 ± 2) °C for (96 ± 1 ) h (four days). 5.6.1 Equipment If not otherwise specified, the following equipment shall be used: – a glass cylinder of 7 cm to 8 cm in diameter and of 9 cm to 1 0 cm in height; – an oven without forced air circulation and with a rate of ventilation of 6 to 1 0 air changes per hour.
5.6.2 Procedure Viscosity of the varnish sample shall be determined in accordance with 5.3 at (23 ± 0,5) °C. A varnish sample of (1 50 ± 1 ) g shall then be weighed into the glass cylinder and shall be placed in the oven maintained at (50 ± 2) °C. Every 24 h an amount of solvent and/or diluent as agreed between supplier and purchaser shall be added to compensate for that lost by evaporation and shall be properly mixed with the varnish. When the same procedure is completed after 96 h, the viscosity of the varnish shall be determined according to 5.3 at (23 ± 0,5) °C. 5.6.3 Result One measurement shall be made and the type of solvent and/or diluent as well as the viscosity before and the viscosity after temperature exposure shall be reported. 5.7 Drying and/or curing in thick layer Drying and/or curing in thick layer is expressed by the condition after curing of the top side, bottom side and interior of the specimen. 5.7.1 Equipment The following equipment shall be used: – flat and smooth square pieces of aluminium foil, 0,1 mm to 0,1 5 mm in thickness, having a side length of (95 ± 1 ) mm; – a square form made of metal or any suitable solid material (25 ± 1 ) mm in thickness and having a side length of (45 ± 1 ) mm; – an oven with forced air circulation and with a minimum rate of eight fresh-air changes per hour. The oven shall be of the type and design used for drying and/or curing specimens.