IEEE 841-2021 IEEE Standard for Petroleum and Chemical Industry— Premium-Efciency, Severe-Duty, Totally Enclosed Squirrel Cage Inducton Motors from 0.75 kW to 370 kW (1 hp to 500 hp)

IEEE 841-2021 IEEE Standard for Petroleum and Chemical Industry— Premium-Efciency, Severe-Duty, Totally Enclosed Squirrel Cage Inducton Motors from 0.75 kW to 370 kW (1 hp to 500 hp). 6.4.2 Temperature rise When operated on sinewave power at rated voltage, frequency, and power (1.0 service factor), the average temperature rise of any phase of the stator winding shall not exceed 80 °C as determined by the winding resistance method. When operated on an ASD at nameplate rated speed, motors shall have a maximum 95 °C stator temperature rise by resistance at 1.0 per unit torque. NOTE—If a motor is supplied from an ASD and will operate near the motor’s nameplate rated speed and shaft load, winding and bearing temperatures will be higher than if the motor were supplied from sinewave power for the same operation. The use of the next higher power rating is recommended to avoid reduced motor life. 6.4.3 Surface temperature Maximum exposed internal and external surface temperatures shall not exceed 200 °C (392 °F) under usual service conditions, at rated power. 7. Mechanical features 7.1 Bearings and lubrication Bearings and lubrication shall be as follows: a) Horizontal and vertical ball bearing and roller bearing manufacturing tolerance limits shall be in accordance with Table 4 of ABMA 20-2020. Ball bearings used in horizontal motors shall have ABMA C/3 clearances. b) Bearings shall be greaseable without disassembly 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 so that entry of oil or grease into the motor interior is minimized. Bearings and grease reservoirs shall be protected from entry of contaminants per 5.5. 7.3 Frames, endshields, and fan covers Frames, endshields, and fan covers shall be as follows: a) Frames, endshields, and fan covers shall be of cast iron construction. For frames 449T and above, fan covers may be of cast iron, cast steel or fabricated from steel plate with a minimum thickness of 2.8 mm (0.11 in). b) Fan covers shall be guarded as defned in NEMA MG 1-2016 clause 1.26.3 c) A drilled and tapped hole for a ground lug shall be provided on the motor frame, external to and on the same side as the terminal box. Minimum hole size shall be 1/4 unifed coarse inch thread...