Insulated bearings at the none-drive end2015-08-21
Generators and motors have at least one insulated bearing, usually at the non-drive (exciter) end. In some cases both the drive- and the non-drive-end bearings are insulated.
In most cases, the bearing pedestal or housing is mounted on phenolic sheets, and the holddown bolts have phenolic sleeves and washers. On larger generators, the bearing housing is attached to an end plate. In this instance, the insulation is placed between the bearing housing and the end plate.
Sometimes, it will be difficult to visually detect any isolation, as it may well be an integral, internal part of the bearing assembly. Spherical bearing alignment pads are sometimes installed with phenolic insulation (colored red) between them. In bearing blocks supplied by some bearing OEMs, a layer of PTFE insulation is found on the bearing housing spherical location or seating.