The responses to can I run a 50hz motor on 60hz and a 60hz motor on 50hz are incorrect. Motors are designed to operate within a limited voltage and frequency variation. Voltage variation at motor nameplate frequency must be within plus or minus 10percent and frequency variations at motor nameplate voltage must be within plus or minus 5 percent.The combined variation of voltage and frequency must be limited to the arithmetic sum of 10percent. What is important is the flux density ratio, which is the ratio of line voltage over line frequency. FDR for a 460/3/60 is 7.67vhz. If this motor was to operate on 380/3/60 which has a FDR of 6.33 the percent variation is 17percent which is above the 10 percent arithmetic variation allowed so a 460-3-60 motor could not operate on 380-3-60. Again if a European 415-3-50 motor with an FDR of 8.3vhz was to operate on 460-3-60 with a FDR of 7.66vhz this would be okay as the percent variation is 8.35 percent which is below the 10 percent allowable arithmetic variation. If the motor was to operate on 400-3-60 with a FDR of 6.66vhz the variation is 25 percent so the motor could not be used as the variation is way above the 10 percent maximum arithmetic variation. If the flux density ratio is not checked and the variation is above 10 percent, then undoubtedly the motor may well run above its allowable temperature rise for the insulation class and speed plus pull up plus pull out torque plus PF plus slip plus FLC will all be effected adversely. Do not listen to anyone who advises 50hz motors can run on 60hz or 60hz can run on 50hz, check the flux density ratio.
Reply : You are correct, the important parameter is the flux density and provided that this is equal to the design flux density, there is no problem. V/Hz for a 460 Volt 60Hz motor equals 7.67 The V/Hz at 380V 50Hz is 7.6 so there is no problem running the 460V 60Hz motor on 380V 50Hz provided that the power is reduced by the speed ratio.
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