NEMA MG 1-2011 Information Manual
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Condensed MG 1-2011Page 10© 2014 National Electrical Manufacturers Association8.2 Frame AssignmentsFrame assignments for alternating current single-phase, Design L, horizontal and vertical, open typemotors are given in Table 14. Frame assignments for alternating current, polyphase, squirrel-cage,Designs A, B, and C, horizontal and vertical motors, open type and totally enclosed fan-cooled type aregiven in Table 15, Table 16, Table 17, and Table 18. [MG 1, Part 13]8.3 Lettering of Dimension SheetsDimensions on dimension sheets shall be lettered in accordance with Table 19. [MG 1-4.1]8.4 Tolerances for Shaft RunoutThe tolerance for the permissible shaft runout, when measured at the end of the shaft extension shall be:[MG 1-4.9.7]a) For 0.1875 to 1.625-inch diameter shafts, inclusive—0.002-inch indicator reading.b) For over 1.625 to 6.500-inch diameter shafts, inclusive—0.003-inch indicator reading.Note: Standards have not been established for shaft runouts where the shaft extension length exceeds the standard. However,runouts for shafts longer than standard are usually greater than those indicated above.8.5 Grounding Means for Field WiringWhen motors are provided with terminal housings for wire-to-wire connections or fixed terminalconnections, a means for attachment of an equipment grounding conductor termination shall be providedinside, or adjacent to, with accessibility from, the terminal housing. [MG 1-4.20]9 TESTS AND PERFORMANCE—AC SMALL AND MEDIUM MOTORS9.1 Routine Tests for Polyphase Medium Induction MotorsThe method of testing polyphase induction motors shall be in accordance with IEEE Std 112.Typical tests which may be made on motors completely assembled in the factory and furnished with shaftand complete set of bearings are as follows: [MG 1 12.55.2]a) Measurement of winding resistanceb) No-load readings of current and speed at normal voltage and frequency. On 50 hertz motors,these readings may be taken at 60 hertz.c) Current input at rated frequency with rotor at stand-still for squirrel-cage motors. This may betaken single-phase or polyphase at rated or reduced voltage. (When this test is made single-phase, the polyphase values of a duplicate machine should be given in any report.) On 50 hertzmotors, these readings may be taken at 60 hertz.d) High-potential test9.2 High-Potential Test Voltages for Induction Motors [MG 1-12.3]Category Effective Test Voltage DurationA. At-the-factory tests1. Motors rated 1/2 horsepower or less and 250volts or less1000 volts 1 minute2. Motors rated 1/2 horsepower or less andgreater than 250 volts1000 volts + 2 times the rated voltage of the motor 1 minute3. Motors rated larger than 1/2 horsepower 1000 volts + 2 times the rated voltage of the motor 1 minuteB. After-factory tests1. Initial test of stator assembled atdestinationUse factory test voltages (A)2. Test of an assembled group of motors andapparatusUse factory test value of the lowest of the grouptest value (A) times .803. Additional tests made after installation Use factory test values (A times .75) |
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