Current transformer parameters and structure
01Current transformer
I. Introduction
Now I have a current transformer on hand. Its primary side passes 20A and its secondary side is 20mA. It is also noted below that the operating frequency is 50Hz, and I don’t know what this parameter 0.1 means. 20 ohms. What resistor does it correspond to? Let's make a preliminary measurement of this current transformer.
2. Sensor electrical parameters
First, use SmartTweezer to measure the parameters of the primary side. The corresponding inductance is 124.3 microhenries and the resistance is about 0.1 ohms. The secondary side parameters are not very stable, and the resistance is about 20.25 kiloohms and 126.3 henries. The measurement frequency is 100Hz. According to the primary and secondary inductances, the difference between them is about one million. ·Then the ratio of the two turns should be 1000. This is consistent with the current sensor's transformation ratio being 1000.
▲ .原边参数：0.1欧姆， 124.3微亨
▲ .副边参数： 20.25k欧姆， 126.3亨
3. Internal structure
Next, use diagonal pliers to open the bottom cover of the sensor. You can see the internal structure. There is a magnetic ring inside, and the primary side of the current sensor has only one turn, which is a very thick metal wire as the primary side. The secondary edge is densely wrapped with this thin line. According to the previous measurement results, the number of turns on the secondary side should be 1000.
※ Summary ※
This article measured a current transformer on hand. The inductance ratio between the primary side and the secondary side is approximately 1 million times, which corresponds to a current transformer primary and secondary coil turns ratio of 1000:1. This is exactly the current ratio of the current transformer. However, what do the parameters on the current transformer, 0.1 and 20 ohms behind 50Hz, mean? If anyone knows, please help explain.
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