Abrasive cleaning of inner cooled generator coils

A method for abrasive cleaning of an internally cooled generator coil is presented. A shear hardening medium (12) with suspended abrasive particles is filled into cooling passages of the generator coil. Hydraulic pressure is applied to the shear hardening medium which locks the abrasive particles into a matrix position. A flow (14, 17) is imparted to the shear hardening medium with the cooling passage which applies a shearing force to the shear hardening medium. The locked abrasives (13) and the shearing force abrade an inner wall of the cooling passage (2) and remove deposits and products of corrosion (11) from the inner wall of the cooling passage. After removing the deposits and products of corrosion, the hydraulic pressure is released and the shear hardening medium is flushed (18) out of the cooling passages.