Dc fan monitoring and protection

Although the frequency conversion motor has high reliability, but it is still a mechanical device, when used for a long time, its speed may fall or even halt, so it’s best to real-time monitor the running status of the fan, easy to find problems in a timely manner.

At present, the mode of fan’s own monitoring alarm sensor and speed sensor of two types, using alarm sensor in the fan speed falls below a certain threshold values give alarm signal, when the fan speed can be realized and the speed signal output of the real-time monitoring.

From fan circuit output alarm signal has a “high level” and “low level” two states, meaning represented two level in accordance with the commonly is logic system, high level said “failure”, “low level” according to “normal”.

From the speed of the fan circuit output signal is usually pulse form, each wave head said fan around a circle, the signal through the data bus directly to the host for display. Some fan is the speed of the output signal is not the real speed of the fan, but the speed of multiples, such as per round two, four or six pulse, must be processed to form reflect the reality of the fan rotation speed signal. If you would like to distinguish between fan speed is real speed or a multiple, tachometer is used to measure the actual speed, and then compare and display the data.

Fan speed signal output from three pin plug, commonly three fuses in the yellow and black + 12 v power supply and grounding, respectively, of a different color line is the rotational speed signal output line. It should be noted that some three fan lead third lead is not speed signal output line, but the speed control signal, through which to the fan motor speed regulation control signal.