Hi everyone! I am in the motor business, and I am often asked about the technical problems of various motors. One of the most asked questions is: "What is the "turnover rate"? How to calculate? Today I will explain it clearly to you in the vernacular, and I guarantee that you will understand it as soon as you hear it!
Let's talk about it first, what is the "turnover rate"?
You can think of it this way: in the AC motor, there is an invisible "magnetic field" that is spinning rapidly, and the speed of this "magnetic field" is called "synchronous speed". But the "rotor" that really drives the machine (the rotating core) will never catch up with this "magnetic field". The difference in speed between the two is called the "turnover rate".
Simply put, it is the gap between "ideal speed" and "actual speed".
Why should we care about this "turnover rate"?
Because it is directly related to whether the motor is good or not! For example, how much power (torque) the motor has, whether it consumes electricity (efficiency), and whether it rotates steadily are all related to it. If you understand the rotation rate, you can choose the right motor and know why the machine has problems.
Step 1: Calculate the "ideal speed" (synchronous speed)
If you want to calculate the difference rate, you must first know what the "ideal speed" is. The formula is simple:
Synchronous speed = (60 × supply frequency) ÷ number of motor poles
Power supply frequency: It is the "heartbeat" frequency of your household electricity. It is generally 50 Hz in China, and 60 Hz in the United States and other places.
Number of motor poles: This is the number of "magnetic poles" inside the motor, common ones are 2 poles, 4 poles, 6 poles, etc., and the motor is generally marked.
For example:
Suppose you have a motor connected to 60Hz electricity, which is a 4-pole motor. Its "ideal speed" is:
(60 × 60) ÷ 4 = 3600 ÷ 4 = 900 rpm
Wait a minute! Don't worry, there's a small pit here. The above formula calculates "how many revolutions per minute", but the actual motor speed unit is "RPM" (revolutions per minute), so the correct calculation is:
Synchronous speed = (120 × frequency) ÷ number of poles
So the correct calculation is: (120 × 60) ÷ 4 = 7200 ÷ 4 = 1800 RPM.
So, the "ideal speed" of this motor is 1800 rpm.
Step 2: Measure the "actual speed" (rotor speed)
Next, you need to know how fast the motor actually spins. This is very simple, take a "tachometer" (also called a tachometer) and shine it on the motor shaft, and you can read the actual speed.
Suppose we measure that the actual speed of this motor is 1750 rpm.
Step 3: Calculate the "turnover rate"
Now, by comparing the "ideal speed" with the "actual speed", we can calculate the conversion rate:
Differential Rate = [(Ideal Speed - Actual Speed) ÷ Ideal Speed] × 100%
To apply the numbers above:
Transfer Rate = [(1800 - 1750) ÷ 1800] × 100% = (50 ÷ 1800) × 100% ≈ 2.78%
Therefore, the rotation rate of this motor is about 2.78%. In other words, its actual speed is 2.78% slower than the ideal speed.
What factors affect the "turnover rate"?
Load size: The heavier the motor belt is doing (such as pumping water and compressor working), the more "strenuous" it is, the slower it rotates, and the greater the rotation difference.
The design of the motor itself: the number of poles of the motor and how the internal coil is wound will affect the rotation difference. Generally speaking, motors with many poles have a low "ideal speed" and a relatively high rotation rate.
Power supply problems: If the voltage is unstable or the frequency changes, it will also affect the speed of the motor, thereby changing the differential rate.
When choosing a motor, why should we look at the "rotation difference"?
If you want the motor to rotate particularly steadily and accurately (such as conveyor belts, fans), then you must choose a motor with a small rotation difference, so that the speed fluctuation is small.
If you want the motor to have a particularly strong force as soon as it starts (such as pumping pumps, air compressors), then you have to choose a motor with a slightly larger differential rate, which starts more powerfully.
What motors do we sell?
At our company, we offer a wide range of AC motors to meet different needs. Whether you're looking for a Multi - color Sewing Machine Motor, an Energy Efficient Equipment Electric Motor, or an Electric Motor Centrifugal Clutch, we've got you covered. Our motors are designed to provide reliable performance and high efficiency, with the right slip characteristics for your application.
Want to buy a motor? Or what else do you not understand?
Just contact us directly! We have professional technical brothers to help you choose the most suitable motor, and we can explain to you any questions!