The Institute of Electrical and Electronic Engineers (IEEE) developed the IEEE 841 motor standard in 1986 for the petroleum and chemical industries to improve the reliability, efficiency and performance of severe duty motors. The conditions and applications in these environments place high levels of mechanical stress on electric motors, and environmental contaminants such as dust, dirt and liquids can cause premature, catastrophic, failure to regular duty motors. 

In short, IEEE 841 motors are designed for severe duty applications in the most demanding industries. The IEEE 841 standard covers the construction of the motor, and specifically “premium-efficiency totally enclosed fan-cooled (TEFC) and totally enclosed nonventilated (TENV), horizontal and vertical, single-speed, squirrel cage polyphase induction motors, 0.75 kW to 370 kW (1 hp to 500 hp), and up to 4000 V nominal, in National Electrical Manufacturers Association (NEMA) frame sizes 143T.” 

The standard covers components such as cast iron frames; stainless steel nameplates; specialized bearings and seals; foot flatness; a non-sparking fan; corrosion-resistant paint systems and, at a minimum, a Class F insulation system. 

The standard also covers features of the motor. IEEE 841 motor features including limits on vibration and noise, IP55 protection, a premium efficiency rating and standard NEMA motor size. 

Additionally, the IEEE 841 specification covers service conditions, such as -25°C to 40°C ambient temperature; a maximum altitude of 1000 m; humid, corrosive or salty environments; full-voltage starting and Class I Division II hazardous locations. And every IEEE 841 must include a five-year warranty from the manufacturer.  

Some key IEEE 841 motor specifications (as of the most recent update published on May 28, 2021)  

Any motor labeled “IEEE 841” must meet every requirement laid out in the standard, although motor manufacturers are permitted to develop products that exceed the IEEE 841 motor specification.  

While IEEE 841 motors usually have a greater initial purchase cost, the upfront investment has the potential to greatly reduce the total cost of ownership over the life of the motor, due to lower energy consumption costs, reduced maintenance downtime and repair personnel costs and less risk of bearing failure. However, it’s important to remember, regardless of the motor, regular preventative maintenance is still critical to ensuring long motor life.  

IEEE 841 is quickly becoming the global standard for harsh conditions and applications. Other severe process industries, such as forest products, mining and cement, have also adopted the IEEE 841 specification as it helps promote uniform motor specification and reduce total cost of ownership.