Transformer is covered in dust

During normal operation, transformers can become covered in dust which needs to be periodically cleaned off to prevent arcing and loss of cooling capacity.

Check: Solution:
Is dust simple non-conductive dust. Denergize and blow off with compressed air.
Is dust corrosive such as salt. Simply blowing off the dust may not be sufficient to protect the transformer from corrosion. Megger checks may not diagnose some of these problems. Transformers may need to be placed in a location away from corrosive dust. The transformer may need to be professionally cleaned by manufacturer or replaced. Please consult factory. Certain coatings such as epoxy (VPE) or encapsulated (potted) transformers are available.
Is dust conductive such as coal, carbon black or metallic. Simply blowing off the dust may not be sufficient to protect the transformer from coronal discharge or short circuiting. Megger checks may not diagnose some of these problems. Transformers may need to be placed in a location away from conductive dust.