IEEE Std 841-2021 pdf download – 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).
4.2 Unusual service conditions Unusual service conditions should be brought to the attention of those responsible for the design, manufacture, application, and operation of the motor. Such unusual conditions include the following: a) Exposure to the following: 1) Lint or dirty operating conditions where the accumulation of dirt will interfere with normal ventilation 2) Nuclear radiation 3) Abnormal shock, vibrations, or mechanical loading from external sources 4) Abnormal axial or side thrust imposed on the motor shaft 5) Altitude or ambient temperature outside the range covered in 4.1 b) Conditions under which the variation from rated voltage or frequency, or both, differ from the limits given in item a) of 6.3.1 c) Conditions under which the ac supply voltage is unbalanced by more than 1% (see Part 14 of NEMA MG 1-2016 13 ) d) Operation at speeds above synchronous speed e) ASD operation as constant torque or constant horsepower operation f) ASD operation at voltage above 1000 V g) Load inertia greater than and/or starting conditions more severe than specifed in Part 12 of NEMA MG 1-2016 when applied to rated frequency sinewave power. h) Exposure to conditions where Ingress Protection Level 55 (IP 55) protection is not suffcient 5. Ratings 5.1 Basis of rating Motors shall be rated on a continuous-duty basis at rated power (1.0 service factor). Motor nameplates may reflect capability above 1.0 service factor. The output rating shall be expressed in power available at the shaft at the specified speed, frequency, and voltage. NOTE—Motors should be applied within their rating based on a service factor of 1.0. In applications requiring a prolonged overload capacity, the use of a higher power rating is recommended to avoid the reduction of insulation and bearing life associated with operation above the 1.0 service factor.
5.2 Frame assignments To the extent applicable, motors shall comply with the frame size assignments of NEMA MG 1-2016, Part 13. 5.3 Voltage and frequency ratings The standard voltage ratings for 60 Hz three phase are 200 V, 230 V, 460 V, 575 V, 2300 V, and 4000 V. Voltage ratings for 50 Hz 3 phase are 220 V and 380 V. When specified, a non-standard voltage shall be permitted. 5.4 Synchronous speed ratings Synchronous speed ratings at 60 Hz are 3600 r/min, 1800 r/min, 1200 r/min, or 900 r/min. Synchronous speed ratings at 50 Hz are 3000 r/min, 1500 r/min, 1000 r/min, or 750 r/min.