Constant speed refers to the axial flow fan in the rated voltage to the fan's maximum bearing voltage range, speed remains constant. If a 48V fan has an on-line voltage of 110V, the fan maintains its rated speed when the supply voltage is known to be between 48V-72v. This is a very important feature because an axial flow fan with this feature can work safely over a very wide voltage range, for example, a fan with a constant speed, 4200 rpm, and a voltage rating of 48V, when the fan supply voltage varies in the range of 48V-72V, the Fan will always run at the same speed (i.e. 4200RPM) . The CS constant speed function is preset by the internal software of the fan. The maximum speed of the fan is the rated speed of the axial flow fan. Axial flow fan with constant speed function, in the allowable voltage range, speed constant, noise constant, power constant, more conducive to axial flow fan energy saving, longer service life, noise is lower. The above is the constant speed function of the axial flow fan introduced by Dong Xing Yue, we can customize according to the special requirements of customers, if you want to know more you can click on the axial flow fan knowledge