Cleaning Electrical Windings in the Field

The following is highly dependent on the qualifications of personnel performing the work.

  1. Pressure washing and/ or steam cleaning: Old technology that still works well.
  • This method is successful in blasting off contaminates and also “flushing out” items in places that are hard-to-reach. In some instances it cannot flush out all the dirt and oil.
  • It requires a time consuming process to dry the windings sufficiently. Depending on the size, it can take many days to thoroughly dry the windings.
  • Care taken to not exceed 200 Deg. F when drying out. (See article on field drying)
  • If the windings are not thoroughly rinsed, the soap residue can serve as a contaminant and cause premature loss of insulation integrity.
  • The washing solution must be disposed of properly.
  1. Solvent based cleaning: An additional old cleaning method.
  • Best used on windings with good modern insulation that have oil contamination.
  • Can also be successful in flushing windings. Because the electro-clean is much more expensive than soap and water and quickly evaporates, not as much flushing takes place. Frequently, the result is you have taken the surface contaminates and pushed them deeper into the winding. This is not good.
  • The drying time is considerably quicker than the pressure washing method.
  • Solvent fumes are hazardous. Care must be taken that fumes do not affect the person applying the solvent or anyone nearby. A respirator must be used.
  • Care must be exercised around rubber products especially rubber based lead
  • The solvent solution must be disposed of properly. Improper disposal can result in significant environmental consequences.
  1. Dry Ice blast cleaning: A relatively new technology.
  • Is very successful in cleaning. Uses special nozzle nozzles designed to maximize areas cleaned. Does very little flushing, therefore does not move the dirt to hidden
  • It uses dry ice pellets accelerated to high velocity by a specially designed machine. The dry ice instantly freezes the contaminant and breaks the bond with the surface. The hyper velocity air removes the dirt and the dry ice instantly changes into an inert gas C02.
  • There is no drying process required.
  • There are minimal disposal issues. Sweep up the dirt and use a dustpan.
  • In short, this method is quicker and safer than either of the previous methods.
  1. Hand cleaning with qualified personnel: The safest was to clean.
  • The lease intrusive way to remove dirt and contaminants from insulation. The disadvantages are: it is labor intensive and is limited to the reachable areas.

There is no perfect way. Choose the best cleaning method to solve your problem.

References and More Info:

Cleaning Electrical Equipment With Dry Ice, by Cyndi Nyberg
Field-Expedient Ovens, by Chuck Yung