TARDIS ancillary power station

The ancillary power station was an engine room in the Doctor's TARDIS.

The Fourth Doctor used the TARDIS art gallery to hide his from Sontarans. (TV: The Invasion of Time)

When the Doctor's TARDIS suffered a power cut, the Fifth Doctor and Nyssa sought out the ancillary power station in order to restore the power. (AUDIO: The Haunting of Thomas Brewster)