Drying of transformers is mandatory when population deviations depend on the normalized value downwards. To calculate the current insulation resistance of the appropriate configuration, which takes into account the nominal power and voltage of the transformer, as well as a special correction factor that characterizes the effect of temperature on the insulation resistance.
Drying of the power transformer should not cause a sharp change in the temperature of the insulation and windings, as this can lead to damage caused by thermo-mechanical stresses. The temperature of the windings should not increase faster than 5 … 7 ºС per hour.
Drying insulation of transformers can also be control. It is performed in such cases when:
there are signs of wetting of the oil and / or a leakage of the transformer has occurred;
the maximum storage period of the transformer without oil was exceeded or timely refilling was not carried out;
the active part of the transformer stays in an unsealed state longer than the permissible time;
detection of insulation deterioration as a result of routine tests.
The control drying of transformers can be realized by creating a high vacuum and using a low-temperature vapor trap, using direct current or short-circuit currents to heat the windings.
Drying of oil-free transformers is necessary when the insulation is strongly wetted, traces of water appear on the active part or tank, and also when insulation performance has become much worse than normalized values. Technically, this procedure can be carried out using a drying cabinet, a special chamber, or drying in its own tank. The best results in terms of quality are obtained by drying the active part of the transformer under vacuum in a special drying cabinet.
Why the condition of a hydraulic oil worsens
During the operation of equipment equipped with a hydraulic actuator, due to the leakiness of existing compounds, moisture can enter the oil, as well as metal particles resulting from the wear of parts. The environment is a source of pollution by dust. The more foreign matter in the oil, the higher the likelihood of clogging and failure of the entire system. This can result in unplanned downtime and costly repairs.
The transformer drying UVS-6S includes an automated control of the drying process, performed by automatically registering the following parameters:
- heating temperature;
- the degree of vacuum in the installation;
- change in the degree of moisture content of the insulation during the drying process;
- the presence of condensate in the chamber.