Testing of breakdown voltage of transformer oil - electrode preparation
IEC 156 BDV test kit
New electrodes, pitted electrodes, electrodes which have not been properly stored for a considerable time shall be cleaned by the following procedure:
(1) Clean all surfaces with a suitable volatile solvent and allow the solvent to evaporate;

(2) Polish with fine abrasive powder (for example, jeweller's rouge) or abrasive paper or cloth (for example, crocus cloth);

(3) After polishing, clean with petroleum spirit (reagent quality: boiling range 60 degrees - 80 degrees) followed by acetone (reagent quality);

(4) Assemble the electrodes in the cell, fill with a clean, unused insulating liquid of the type to be tested next, and raise the electrode voltage to breakdown 24 times.