This maintenance constitutes the "backbone" of S.T.&M.'s activity. All other activities that S.T.&M. performs derive mainly from this one.

S.T.&M. applies predictive, preventive, and corrective maintenance techniques to all the elements of an electrical high-voltage power system, such as: Power transformers - Instrument transformers - Protective relays - Switchgears - Powering cables - Grounding grids - Isolators - Arresters - Measurement equipment - ...

Although high-voltage maintenance works must be done on completely or partially de-energized systems, S.T.&M. is always flexible and adapts its working procedures to the necessities of individual companies.S.T.&M. provides a 24 Hours Hotline Emergency Service:

Phone: 689 23 49 70 (Vizcaya) / 646 96 83 60 (Burgos)
                                               646 96 83 61 (Burgos).

When maintenance services are completed, S.T.&M. provides an extensive report containing the recommendations for the best maintenance of the system according to the results of the measurements and checkings.