Lubrication of electric motors as defined by IEEE standard 841-2009, shortcomings and potential improvement opportunities

The technology involved in lubrication of electric motor bearings has been moving steadily forward. The current wording covering the grease(s) qualifying for motors meeting this standard is spelled out in Section 6.1g of the Institute of Electrical and Electronic Engineers Standard 841; “Bearings shall be suitable for, and shipped with, rust-inhibiting grease compatible with polyurea-thickened grease.” There are two significant problems with this statement in today's operating environment: 1) how does one define compatible; and 2) these same polyurea-thickened greases have shortcomings that can be overcome by alternative grease technologies. In fact, polyurea thickeners are now broken into two performance categories, conventional and shear stable, and they may not be compatible with each other. Interestingly enough, some of these new grease technologies may well be compatible with the polyurea thickeners depending on the definition of that same troublesome word - compatible. The goal of this paper is to recommend improvements to update Section 6.1g by illustrating the issues with the above points so that both original equipment manufacturers and users can be confident that they are drawing maximum performance potential from their electric motors while providing flexibility to address significant specific end-use performance requirements.