The motor speed is also the rated speed of the motor. It refers to the speed of the motor at the rated power. That is, the motor speed at full load, so it is also called full load speed. It is represented by the symbol "degree N" in the unit of "RPM". Different uses and types of motor, different speed.
Motor speed calculation Synchronous motor speed =60* frequency known/log of magnetic pole track (n=60* F/P) n -------- Motor speed (RPM)
F ------- Alternating current frequency, unit: Hz
P ------- Motor pole logarithm (pair), unit: pair (P).
8 pole: 60*50/4=750 RPM, asynchronous speed slightly reduced about 735 RPM;
6 pole: 60*50/3=1000 RPM, asynchronous speed slightly reduced about 980 RPM;
4-pole: 60*50/2=1500 RPM, asynchronous speed slightly reduced about 1475 RPM;
2-pole: 60*50/1=3000 RPM, asynchronous speed is slightly reduced by about 2970 RPM.
When the motor is idled, the speed is Ns= 60F /P, and P is the log pole. For example, if the number of poles is 8 on the motor, then the log pole P=4. However, the number of poles should be written on the motor, not the number of poles. Speed is measured in r/min, or revolutions per minute.
If the motor is not empty, but with load, there is no way to calculate. When the motor is designed, there is generally a working condition. If the motor is working in the working condition, the speed is the rated speed on the motor brand.
If the motor and load do not match, load more than the rated load and power of the motor, the motor speed is lower, but the motor should not work in this case, because the load is too large, the motor with fixed, or slow, lead to motor cooling fan on the shaft's own work is not good, cause the motor temperature rise is too high, burning motor, if is to use the inverter frequency conversion runtime, If the frequency is too low and the motor speed is too slow, additional electric fans are required to heat the motor. This situation must be avoided.
