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I. Preface
Now you have a current transformer on hand, which passes 20A on the primary side and 20mA on the secondary side. It is also noted below that the operating frequency is 50Hz, and the parameter of 0.1 does not know what it means. 20 ohms. What resistor does it correspond to? Let's take a preliminary look at this current transformer.
Second, the electrical parameters of the sensor
First, the parameters of the primary side are measured using SmartTweezer, which corresponds to 124.3 microhenries on the inductance and a resistance of approximately 0.1 ohms; The secondary parameters show less stability, with a resistance of about 20.25 kohms and 126.3 henries. The measurement frequency is 100Hz. According to the primary and secondary side inductance, they differ by about one million. Then the ratio of the number of turns between the two should be at 1000. This is consistent with the current sensor's transformation ratio of 1000.
▲ Primary side parameters: 0.1 ohms, 124.3 microhens
▲ Secondary side parameters: 20.25k ohms, 126.3 Heng
Third, the internal structure
Use the diagonal clamp below to open the bottom cover of the sensor. The internal structure can be seen. There is a magnetic ring inside, and the primary side of the current sensor is only one turn, which is a very thick metal wire as the primary side. The secondary edge is densely wound around this thin line. According to the previous measurements, the number of turns on the secondary side should be 1000 turns.
※Summary ※
This article measures a current transformer at hand. Its primary side to secondary side inductance ratio is about 1 million times, which corresponds to a current transformer primary side and secondary side coil turns ratio of 1000:1. This is exactly the current ratio of the current transformer. But what exactly do the parameters on the current transformer, 0.1 and 20 ohms after 50Hz, mean? Anyone clear, help explain.