How to test the actual speed value of the cooling fan

The speed of the cooling fan refers to the number of times the fan blade rotates per minute, and the unit is rpm; the general cooling fan standard is positive and negative two wires for the power supply. The cooling fan can be equipped with a three-wire FG speed measurement signal and a three-wire RD alarm signal according to the actual situation of the equipment And four-wire PWM speed control signal, but they all need to reconfigure the interface and will increase the cost of the standard two-wire cooling fan. Generally, customers use the cooling fan FG signal to detect the fan’s real-time speed more widely; then the interface does not change and reduces the cost In the case of using a standard two-wire cooling fan, how should we measure the real-time speed of the fan? u003cbru003e u003cbru003e u003cbru003e There are many ways to detect the real-time speed of the cooling fan, such as oscilloscope, current hook gun, DC source, etc. Today we will introduce in detail how to use the oscilloscope to measure the actual speed of the cooling fan. The content to be tested is as follows: u003cbru003e u003cbru003e u003cbru003e 1. The DC voltage must be consistent with the rated voltage of the cooling fan under test u003cbru003e u003cbru003e u003cbru003e 2. Test the input current waveform of the cooling fan power supply u003cbru003e u003cbru003e u003cbru003e 3. Read the X axis time of 4 cycles. (Generally, the DC axial flow fan has 4 pairs of logarithms) u003cbru003e u003cbru003e u003cbru003e 4. The formula for calculating the speed of the cooling fan by reading the data on the oscilloscope is: u003cbru003e u003cbru003e u003cbru003e Fan speedu003d60 seconds/cycle*4 u003cbru003e u003cbru003e u003cbru003e As shown below u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e According to the oscilloscope display current waveform cycle *4 is 22.5ms u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e u003cbru003e Calculation of the actual speed of the cooling fan: 60000/22.50msu003d2667rpm, from which the actual speed of this cooling fan is obtained. This is how the oscilloscope measures the speed of the cooling fan. Other methods of measuring the speed of the cooling fan will be introduced in turn ； u003cbru003e u003cbru003e u003cbru003e Tongchi Auto focuses on the field of cooling fans, provides professional technical support, can carry out product collaborative design according to user needs, and provide overall cooling solutions.