Is it easy for a 380V motor to burn out under grid fluctuations around 400V?
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The factory needs motors for water pumps with a voltage of 380VAC, but upon visiting the site and consulting the project owner’s engineer, it was stated that the voltage in the substation actually ranges from 3x400V-15% to 3x400V+10%, which is higher than 380V. He suggested that if the variable-frequency motor is equipped with a separate fan, either a 400V model should be used or a fan mounted on the same axis as the motor; otherwise, the low power of the separate fan may cause it to burn out. In this case, could small motors (not limited to 100W motors such as those in standalone fans) also burn out due to voltage exceeding the designed value?
There’s no problem per se; however, one thing to consider is that for such a small motor, connecting its power supply directly to the transformer’s low-voltage side requires thermal stability calculations. The rated current cannot be the only factor to consider for cables
For motors with a low voltage of 380V, the corresponding voltage grade is 400V. You can take a look at the nameplate of the distribution transformer; it shows 10KV/0.4KV. What usually causes a motor to burn out is high current and overheating. The voltage fluctuates within the allowable range, and generally does not cause the motor to burn out.