The absence of oil does not mean a dry-type transformer needs no maintenance. Dust, humidity, cooling and connection temperature still require attention, while oil sampling and DGA do not apply.
This guide is general information. HV/MV intervention and testing must be carried out by qualified personnel under the equipment manual and facility safety procedures.
Environment and cleanliness
Check airflow, filters, dust build-up and moisture in the transformer room. Choose cleaning methods specified by the manufacturer; unsuitable compressed air or solvents can damage insulation surfaces.
- Air passages and fans
- Coils and insulation surfaces
- Dust and humidity
- Temperature sensors and alarms
Measurements and thermal review
Where appropriate, examine connections, insulation resistance and thermal images. More advanced diagnostic methods depend on the transformer design and symptoms. Interpret readings with test temperature, duration and previous trends.
Record and follow up
Document contamination, looseness, hot spots or insulation concerns. Keep corrective work and repeated measurements with the same equipment record. Adjust the review interval to environment and operational criticality.
Focus on environment and insulation surfaces
Airflow and clean insulation surfaces are central to dry-type transformer reliability. Room temperature, fan operation and blocked ducts are reviewed alongside loading. Cleaning must follow manufacturer instructions; unsuitable solvents or aggressive compressed air can damage insulation. Thermal checks document connection temperatures and phase differences. De-energized insulation readings are compared with temperature and earlier results rather than treated as a stand-alone pass mark.
Decision checklist
- Room airflow and fans
- Dust, humidity and insulation surfaces
- Connection temperature and thermal images
- Earlier insulation measurements
Related service
Dry-Type Transformer Maintenance →
Request technical support →Frequently asked questions
Is oil analysis used on a dry-type transformer?
No. There is no oil to sample.
Are dry-type transformers maintenance-free?
No. Environment, cooling, connections and insulation still need checking.
Is oil testing relevant to a dry-type transformer?
No. Oil sampling and DGA do not apply to a design without insulating oil.
