Siemens & IBT

Many industries are beginning to utilize the IEEE 841 standard when specifying and procuring electric motors. IEEE 841 was originally developed as a standard for the petro chemical industry to establish performance and testing specifications with the intent of lowering the total cost of ownership of individual motors.

IEEE 841 specification is confined to describing TEFC (Total Enclosed Fan Cooled), Severe duty, Premium Efficient, squirrel cage induction motors up to and including 500 horsepower, voltage through 4,000 V (typical 460 or 575 V) 60HZ.

One area of interest is IEEE 841-1994, which specifies regreasable bearings.

Image courtesy of Siemens

1. Sealed bearings have a finite life. When that life is expended, the bearing fails unexpectedly. There is no way to extend the life without taking the motor out of service and replacing the bearing. 

2. The life of a regreasable bearing can be increased significantly by proper lubrication intervals.  One of the main enemies bearings have is grease contamination. Specifications require inner bearing caps and seals to reduce grease contamination problems.

Also, if a motor bearing starts to become noisy, relubrication can allow the bearing to continue operating until a convenient time can be found to take the motor out of service without loss of production.

3. The amount of grease contained in the chamber surrounding a regreasable bearing is significantly more than in a sealed bearing. If the grease is not contaminated, generally the bearing life is longer than that of a sealed bearing.

Testing and documentation also are defined by the 841 standard, required routine tests include: measurement of windings resistance, Current, Power, Speed (measured at load, rated volts and speed), and High Potential Test. All the above tests are defined by NEMA MG 1. Additionally motors are tested for vibration, to pass motors must meet the minimum standard of 0 .06 IPS for vibration and 0.005” foot flatness or better.

Siemens Industries is producing a complete line of motors designed to meet the IEEE 841 Specification. Siemens SD100 841 motors meets or exceeds IEEE 841-2001 standards for, high performance, variable speed operation, rugged construction and long service life for the most demanding applications.

The SD100 841 motor is available in two rotor designs aluminum (1-400HP) or copper (1-20HP). These motors offer efficiency levels exceeding the Energy Independence and Security Act Efficiency Levels mandated for 2010.

Stator/ Windings feature a unique stator core design lowering flux density while increasing the cooling capacity.

A proprietary inverter-rated NEMA Class F hygroscopic insulation system provides extra margin increasing the thermal life of the motor. This insulation system meets or exceeds MG1-2003 Part 31, making all motors suitable for operation with variable frequency drives

Bearings are regreasable, oversized single-shielded with cast iron inner caps. Inpro/Seal bearing isolators are standard on both bearing housings.

While no motor is indestructible, Siemens SD100 841 motor is designed be applied in the most demanding of environments. As a result, Siemens motors deliver the lowest cost of ownership in the industry over a motor's lifetime.

For more information, contact your local IBT Sales representative or local IBT branch.