Editing Compressor (section)

==Lubrication==
Compressors that are driven by an electric motor can be controlled using a [[variable-frequency drive|VFD]] or [[power inverter]], however many hermetic and semi-hermetic compressors can only work in a range of or at fixed speeds, since they may include built-in oil pumps. The built-in oil pump is connected to the same shaft that drives the compressor, and forces oil into the compressor and motor bearings. At low speeds, insufficient quantities of oil reach the bearings, eventually leading to bearing failure, while at high speeds, excessive amounts of oil may be lost from the bearings and compressor and potentially into the discharge line due to splashing. Eventually the oil runs out and the bearings are left unlubricated, leading to failure, and the oil may contaminate the refrigerant, air or other working gas.<ref>{{Cite web|url=https://toshiba-mirai-kagakukan.jp/en/learn/history/ichigoki/1981aircon/index.htm|title=Toshiba Science Museum : World's First Residential Inverter Air Conditioner|website=toshiba-mirai-kagakukan.jp}}</ref>