servicing / maintenance / dehydration of transformer installed at substation of 75 bn bsf under shq bsf gopalpur.; 1 routine maintenance of transformer in operating covering insulation resistance oil breakdown strength, reconditioning / replacement of silica gel, cleaning of transformer & topping up to oil if required etc as reqd upto 500 kva. 2 filtration of transformer oil for removal of moisture, carbon, slurry etc. by means of circulating oil through vacuum pump from heating elements and filters to withstand the breaking strength of the oil above 40 kv beyond one minute tested in oil testing kit. 3 testing of transformer oil for dielectric breakdown strength per sample 4 supplying and filling of transformer oil gaving good resistance to high electrical stress, high dielectric strngth ( 50 kv ) low viscosity, low pour point, high flash point and excellent thermal properties for efficient heat tranfer and cooling as per is : 335, 1072 isi marked into the existing transformer.