IEEE 841:2009 pdf free download – IEEE Standard for Petroleum andChemical Industry-Premium-Efficiency, Severe-Duty,Totally Enclosed Fan-Cooled (TEFC) Squirrelage Induction Motors – Up to andlncluding 370 kW (500 hp)
4.5 Enclosures
Enclosures shall be TEFC or totally enclosed non-ventilated(TENV) and shall have a degree of protectionof lP 55.If replaceable shaft seals are used to achieve this degree of protection, they shall be the noncontactor noncontacting-while-rotating type with a minimum expected seal life of 5 years under usual serviceconditions.Degrees of protection are defined in NEMA MG 1-2006，Part 5.3 Drain fitting holes arepermitted to be plugged during the enclosure IP 55 ingress test.
5.1 General
Unless otherwise specified in this standard,motor electrical performance and characteristics shall be inaccordance with NEMA MG 1-2006.
5.2 Motor designs and starting characteristics
Motors shall have Design B torque/current characteristics and starting capability as defined in NEMAMG 1-2006,Part 12.Where power and speed ratings fall outside Part 12, characteristics and capabilitiesshall meet or exceed the specifications defined in NEMA MG 1-2006,Part 20.
4.5 Enclosures
Enclosures shall be TEFC or totally enclosed non-ventilated(TENV) and shall have a degree of protectionof IlP 55.If replaceable shaft seals are used to achieve this degree of protection, they shall be the noncontactor noncontacting-while-rotating type with a minimum expected seal life of 5 years under usual serviceconditions.Degrees of protection are defined in NEMA MG 1-2006，Part 5.3 Drain fitting holes arepermitted to be plugged during the enclosure IP 55 ingress test.
5.1 General
Unless otherwise specified in this standard，motor electrical performance and characteristics shall be inaccordance with NEMA MG 1-2006.
5.2 Motor designs and starting characteristics
Motors shall have Design B torque/current characteristics and starting capability as defined in NEMAMG 1-2006,Part 12.Where power and speed ratings fall outside Part 12, characteristics and capabilitiesshall meet or exceed the specifications defined in NEMA MG 1- 2006,Part 20.
6.1 Bearings and lubrication
a)Horizontal and vertical ball bearing and roller bearing manufacturing tolerance limits shall be in accordance with Table 4 of ABMA 20-1996.Ball bearings used in horizontal motors shall haveABMA C/3 clearances.
b)Bcarings shall be grcasable without disasscmbly of fans or fan covers and shall contain a reservoir equipped with outlet plugs that extend beyond the fan cover for elimination of purged grease. Oil-lubricated bearings may be furnished for vertical motors.Inner bearing caps shall be provided sothat entry of oil or grease into the motor interior is minimized.Bearings and grease reservoirs shallbe protected from entry of contaminants per 4.5.
For vertical flange-mounted motors with a thrust-loading,angular contact ball (single or duplextype), Conrad decep-groove or spherical roller thrust bearings are recommended, depending on therequirements of the application. Filling-slot (maximum-load)antifriction bearings shall not be usedin any motor. The manufacturer shall note thrust bearings of other construction. P-base motors shallhave the thrust bearing at the nondrive end. Where the motor shaft is solidly coupled to the drivenapparatus,the thrust capacity of the thrust bearing shall be sufficient to carry the weight of therotating element of the motor and the external axial thrust loads (in cither or both directions) aswell as the radial load specified.
NOTE—Vertical motors purchased in combination with pumps (vertical overhung and vertically suspendedtypes) specified in accordance with API Std 610-2004 may have more stringent thrust-bearing loadingdefinition and life requirements than specified in item e) and item d) of 6.1.For vertical overhung andvertically suspended applications, both the motor and the pump impose radial and thrust loading on the motorbearings. The maximum radial and thrust loading that occurs during start-up and cend-of-pump-curve operationcan be severe and difficult to predict, and conservatism in bearing specification is recommended.