Everyone knows that cooling fans are used to exhaust air and dissipate heat, but do you know other functions of cooling fans? In fact, it has fourteen functions. Here, Fengheng Technology will give you a popular science to give you a more comprehensive understanding of the functions of cooling fans.
1. SS function (soft start function): When the fan is powered, the current starts from zero and gradually increases until the fan reaches the maximum speed and rated current. The maximum current at startup is equal to the free running current (or in a few cases, the rotor is locked and restarted). The fan will reach the rated speed within 5 seconds.
2. LP function (lock protection and current limiting restart): The automatic start function ensures that the fan motor will automatically restart in case the fan blades are blocked. When the rotor is locked, the fan current will be reduced to zero and the fan will restart after 5 seconds.
3. FG function (frequency generator or output tachometer): This is an open collector output connected to a “pull-up” resistor and a compatible reading device’s input power supply voltage. This output provides a square wave signal (such as a TTL input computer). The maximum collector voltage may be up to 72 volts DC and the maximum collector current is 10ma. The power supply of the reading device must have the same ground potential as the fan.
4.RD function (rotation detection function) This is an open collector function and is the same hardware function as the FG mentioned above. The signal pin outputs a low level when the fan is running and a high level when the rotor is blocked.
5.RDB function (supplementary rotation detection signal): This is an open collector function and is the same hardware function as the FG mentioned above. The signal pin outputs a high level when the fan is running and a low level when the rotor is blocked.
6.LD function: This is an open collector function and is the same hardware function as the FG mentioned above. When the fan is running at normal speed, it outputs a low level, and when the fan is running at 70% of the target rated speed, it starts to alarm. The reason is that low speed operation may age or reduce the power supply voltage.
7.OVP function (overvoltage protection) built-in: This function detects the power supply voltage and allows operation at the rated maximum operating voltage. Usually the maximum operating voltage (unless otherwise specified) is 20% of the specified rated voltage. If the power supply voltage increases by more than 20%. The fan will stop running and the supply current will be reduced to essentially zero. The maximum overvoltage protection range is twice the rated voltage value, for example if the rated voltage is 24V, the maximum voltage can be applied to 48V. Similarly, for a fan with a rated voltage of 12V, the maximum overvoltage is 24V.
8.TC function (automatic temperature control): When this function is applied, the speed of the fan is controlled by temperature, and different temperatures can correspond to different speeds. CS (constant speed), SS (soft start function) and CL (current limiting) functions are all included.
9.RC function (manual control variable resistor): When this function is applied, the speed can be controlled by using an external variable resistor, and the maximum value of this resistor can be selected in the range of 10k to 100k. The fan speed will change linearly CS (constant speed), SS (soft start function) and CL (current limiting) functions are all included.
10.CL function: In this function, the current is limited during the lock period.
11.CS fixed constant speed function: This is a very important function because it allows the fan motor to operate safely over a very large power supply voltage range. For example, if the fan motor is designed to run at 4200RPM. The rated voltage is 48V, the fan motor will maintain the same speed even if the power supply voltage changes from 48 to 72V. The CS fixed speed function is built-in, and the maximum speed is the constant speed.
12. VC function (DC voltage signal control): In this function, the speed is controlled by the voltage signal level to control the fan speed. Different input voltages can correspond to different speeds. The voltage signal can generally be set in the range of 0-10V (-generally recommended to use 0-5V).
13. CC function (current source signal control): In this function, the speed can be controlled by applying an external current source signal. Different input currents can correspond to different speeds. The current signal can generally be set in the range of 4mA-50mA (generally recommended to use 4-20mA).
14. PWM function (pulse width modulation signal control): The PWM function can use frequency and high and low voltage levels to control the fan speed. Under this function, the frequency can be adjusted from 30Hz-30KHz, the high level voltage range can be adjusted from 3V to 10V, and the low level range is ≤0.8V. The fan speed can be linearly controlled by adjusting the “duty cycle” until the fan reaches its maximum speed. CS (constant speed), SS (soft start function and CL (current limiting) functions can all be included.
The above are the 14 functions of the cooling fan. Shenzhen Fengheng Technology Co., Ltd. is an enterprise integrating mold design, development, and finished product assembly of AC and DC brushless cooling fans. If you need to buy a cooling fan or want to know more about the cooling fan, you can contact us.