The maintenance of an OLTC is conducted under the following:

  • Number of operations according to the manufacturer’s manual, that ranges from 100.000 operations depending on the type of OLTC.
  • A diagnostic analysis through oil quality testing or DGA that indicates the changes in the oil or if there are any combustible gases being generated that exceed the acceptable limits.
  • Visual inspection where leaks due to deteriorated gaskets are detected.
  • Mechanical or electrical problems due to the motor drive unit.

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Oil drainage and preparations for the removal of the diverter switch using a crane.

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Removal of the diverter switch.


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Removal of the diverter switch.


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Examination and cleaning of the diverter switch.


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Electrical testing on the diverter switch and contact measurements.