An international supplier to the aerospace industry uses large commutator DC motors on their drive stands used to test all motors before shipment.
A cooling motor is used to supply cooling air to the commutator drive motors. The plant air used for cooling contains a small amount of oil mist. This oil mixes with the DC drive brush residue and causes a dielectric failure with the resulting breakdown in winding insulation. This causes premature failure of the motor windings and results in very expensive repairs being necessary.
A shroud was built around the motor air intakes and Mycelx OilArrest filters were installed.
The oil mist was completely removed from the cooling air and the winding life of the motors has been increased by three to four times.