The shipment of transformers that exceed a certain power rating is made when the transformers are empty and with their radiators/panels disassembled. Furthermore, the humidified oil in the radiators determined through the tests conducted have to be dried from time to time. This procedure is conducted on-site for small transformers to avoid downtime. The mobile on-site services are preferred by small transformers for their advantages and are preferred by larger transformers out of necessity.

Procedures conducted by mobile service vehicles:

1. Assembly disassembly
2. Fixing oil leaks
3. Ratio tests
4. Resistance tests
5. Maintenance of the automatic exchange, change of taps
6. Painting, Cleaning of the transformers
7. Oil tests