The core current probe can test direct current and alternating current, and the methods for testing direct current and high frequency alternating current signals are different. Hall sensors are used to measure direct current and low-frequency alternating current, while current transformers are used to measure high-frequency alternating current. The alternating current generates a magnetic field in the core of the current transformer, and then the current is drawn in the second winding circuit and fed into the oscilloscope. As follows:

The structure diagram of the hybrid AC/DC probe is as follows:

In the derating curve, the maximum continuous current of 15 Arms can only be tested at a frequency lower than 10K.

The main reason for derating the power of the core current probe is that the probe itself heats up when measuring high-frequency and high-amplitude currents. This heat may even cause the probe to melt and damage. There are two main reasons for self-heating:

1. High frequency current generates alternating magnetic field. The magnetic field induces eddy currents on the conductor. The higher the frequency, the greater the eddy current. The eddy current will cause the conductor to heat up and eddy current loss.

2. When measuring high frequency current, the magnetic core current probe uses transformer method to measure. As the high-frequency signal produces a skin effect on the conductor, the resistance of the conductor increases, and the conductor generates heat. The higher the frequency, the more obvious the skin phenomenon.

In order to avoid thermal damage to the core flow probe, the relationship between the frequency of the current to be measured and its harmonic components and its amplitude should be considered when using it.