Axial flow fans are standard on two wires, which is a kind of power system, three-phase five-wire system of course is not meaningless, it has a different definition of each wire color. POWER POSITIVE: Red Power Negative: NEGATIVE SQUARE WAVE FG SIGNAL: yellow, when the axial flow fan operation, the output speed detection signal, when the fan is locked, the output low level signal. Warning RD SIGNAL: Gray, low level output signal: Fan Operation Warning RDB SIGNAL: White, high level output signal: Fan Operation Warning LD signal: Brown, the output low level signal indicates: The speed is below the rated speed of 70% (or to explain and connect a row of axial flow fans in the fan has been aging) PWM SIGNAL: Blue, fixed frequency, duty cycle speed regulation voltage speed regulation VC SIGNAL: Green, voltage signal control speed resistance speed regulation RC SIGNAL: purple, resistance (usually with potentiometer) control speed positive and negative control signal: Yellow Green Zebra Strip color, above is the role of the axial flow fan wire color introduced by Dong Xing Yue, we can be customized according to the customer's special requirements, if you want to know more about axial flow fan knowledge can click: