DC Brushless cooling fans offer various functions, including Alarm Signal and Locked Rotor Signal. Speed control options include temperature sensor control and PWM control for precise adjustments. Additionally, fans may have Auto Restart function to protect against high current burnout and automatically restart when not locked. Mega Tech provides customizable solutions to meet specific requirements.
Here is a brief introducion of it.
FG Signal
Alarm Signal, which is a more common additional control function, the types are as follows. The FG signal is determined by the internal structure of the fan, and the number of magnetic poles may be different for different fans. The FG signal can reflect the true speed of the fan by differentiating the number of poles.
Locked Rotor Signal
Locked Rotor Signal: The RD signal is the Rotate Detection Output, which outputs a “low” signal when the fan is running and a “high” signal when the fan is stopped. When the fan is running, RD outputs a “low” signal, when the cooling fan stops RD outputs a “high” signal.
Therefore, RD function is often used as Alarm function to determine whether the fan is in normal operation or locked by monitoring the level of RD signal: when the fan is running, RD is low, when the fan is locked, RD is high, in order to achieve the purpose of warning the system and protecting the system, this function should be used with the system design.
Speed control
Speed control, in order to give full play to the advantages of DC brushless motor, additional and diversified control is the trend now and in the future, and speed control is a more common design nowadays, generally it has the following types. That’s waht we called PWM,you can refer to article: what’s pwm fan.
RD Alarm
The RD signal line in the fan serves two main purposes:
- Rotation status monitoring: RD outputs “low” for normal fan operation and “high” when the fan stops.
- Alarm protection: RD acts as an alarm when the fan encounters issues like blockage or operational faults. This ensures prompt system protection and safety.
Temperature sensor control (Speed control by temperature sensor)
This is commonly referred to as temperature control.It is the use of thermal resistance as temperature-sensitive components, with the internal circuit settings, so that the speed can match our expected temperature changes. In order to reduce noise and energy demand for environmental protection, the general range of change is between 25 ℃ ~ 45 ℃. It can also be adjusted according to the customer’s needs and is now commonly used in CPU Cooler or Power fan applications.
PWM control (PWM Signal; Pulse Width Modulation): This means that the fan changes its speed with the width of the square wave of the input signal, which is generally used in situations that require more precise speed control.
Two Speed Operation
Using an external signal or switch to switch the speed, generally using the system itself to adjust the voltage to do the control.
In addition, there are some other functions.
Auto Restart
Auto Restart, for the automatic restart function.
When the fan is locked, the fan’s operating current will be automatically cut off, and the fan will work in a low current state, thus protecting the fan from burning out due to high current.
Another function of Auto Restart: every certain time the fan automatically outputs a signal to start the fan, when the fan is not in a locked state, the fan will be restarted and run normally.
For which signal to choose，please check How to choose Fan Function?
Mega Tech can customize your choice to meet even the most demanding restrictions. If you have any questions or wish to learn more about Axial fans, contact Mega team today.
Articles you may also like:
Why Mega Fan is the best alternative to EBM Papst fan
Ball Bearing Fans VS Sleeve Bearing Fans
