The core and coil structure of conservator-type transformers is similar to that of hermetically sealed transformers. Like the hermetic type, they can be designed as ONAN, ONAF, KNAN, and with OLTC. The size of the conservator tanks in these transformers is determined through precise calculations to accommodate the expansion of oil due to temperature increases.
Since conservator-type transformers are exposed to the atmosphere, the changing oil pressure caused by thermal effects is managed through air exchange, where a silica gel (air dryer) absorbs moisture from the incoming air.
Over time, due to continuous air exchange resulting from temperature differences, the silica gel loses its effectiveness, leading to oil moisture absorption and degradation. Therefore, periodic maintenance, such as replacing the silica gel and taking oil samples to measure breakdown voltage, is recommended.
Having a conservator tank is generally preferred in power transformer production. However, due to the air drying system, these transformers can also be used in distribution and transmission lines up to 5 MVA and 36 kV in humid climate regions, depending on customer requirements.
