Bearings in electric motors

Installation of bearings and pulleys Important checks at the time of commissioning Maintenance of electric motors and their checks Maintenance of bearings General problems in electric motors and their remedy Winding temperature measurement at site Analysis of insulation failures of an HT motor at a thermal power station... 

This bearing is best suited to handle radial loads. It doesn t work well with axial/thrust loads. This bearing is popular in electric motors. 

Typical uses of polyimide include electronic applications, sleeve bearings, valve seatings, and compressor vanes in jet engines. Other uses include aircraft and aerospace applications with high performance requirements. They are used for printed circuit boards in computers and electronic watches for both military and commercial uses. Polyimides are used in the insulation of automotive parts that require thermal and electrical insulation, such as wires used in electric motors, wheels, pistons, and bearings. 

The running clearance in a bearing will change with heat buildup and thermal expansion. Because of high coefhcient of thermal expansion values for polymers, they have not been used in electric motors because of small running clearance requirements that is. 

Assemblies of small disks are rotated in a planetary movement around a central screw conveyor. The disks are mounted on six hoUow axles and the axles revolve on overhanging bearings from the gearbox at one end of the vessel where they are driven, via a drive shaft, by an electric motor. The filtrate is collected from the disks via the hoUow shafts and a filter valve into a large collecting pipe. The hoUow shafts also collect the water and air from the dewatering process, in another part of the rotational cycle. The number of disks mounted on the shafts can be adjusted for different materials, depending on the required capacity and the cake thickness to be used. 

These pumps incorporate an electric motor whose rotary assembly is hermetically sealed inside a stainless steel or exotic alloy can. The motor, pump shaft and bearings all operate wet inside the pumped liquid as show ii in Figure 6-12. 

Reduced maintenance costs, leading to an overall improvement in system integrity and reliability. Tlie mean-times-between-failure for active magnetic bearings are equal to tliose of an electric motor. 

XM 3 Normally used in prepacked applications such as electric motor bearings... 

The National Electrical Manufacturers Association (NEMA) has developed a standard that specifies minimum pulley diameters that should be used on electric motors. Since motor bearings are specified using a relatively small maximum overhung load, minimum pulley diameters can have a dramatic effect on motor bearings. The increase in tension that is created by smaller pulleys can transmit a potentially destructive side-load on the bearings. 

---