Commonly used term for mechanical seals in water-cooled generators, mainly turbo generators. The special requirements on generator seals are not concerned so much with the operating conditions but with the relatively large geometrical dimensions and with the – for mechanical seals – big axial displacements. The latter arise between the working state and the installed and start-up state. Generator seals therefore feature purpose-designed springs with special guide pins. Possible applications of these seals are conditional on the maximum producible diameter of the face materials.

By contrast, pumps for the generator stator cooling system (cooling for the stator windings of large generators, e.g. turbo or hydroelectric generators) have shaft diameters of around 30 to 60 mm. Mechanical seals used here seal high-purity water, whose lubricating properties are relatively poor. Experience has shown that the material pairing best suited as regards economy for this case of application is cast chromium molybdenum against antimony-impregnated carbon.

Mechanical seal for a water-cooled 1399 MW turbo generator