The motor in the electric drill belongs to AC universal motor, the speed is high.
Reasons for the high noise of the universal motor:
(1) The high rotor speed in the series motor leads to high sound. The series motor speed usually speeds between 20,000 and 40,000 RPM. Same — output of power. The higher the speed means that the smaller the volume may be done. The higher the speed also means the louder the rotor rotates.
(2) The noise of the variable speed gear accompanied by the series excitation motor. The speed of various power tools, usually between 300 and 30,000 revolutions. Based on volume, stability, friction and other factors, series motors usually through gear deceleration. The sound of gear engagement may sometimes exceed the string motor itself. What really bothers people is the noise above 10K Hz generated from the string motor, and the noise generated by the gear engagement comes to the second place.
As long as the noise of the series motor is large, the induction motor is basically no sound, the sound is also the transmission shaft, the saw blade, with the sound of cutting.
