What Should I Consider When Buying Power Cables?

The power line magnetic ring is the magnetic ring that is usually seen on one or both ends of the power line or signal line of electronic equipment. The power line magnetic ring can form a large impedance to the common mode interference current, but has no effect on the differential mode signal (the working signal is a differential mode signal), so it is simple to use without regard to signal distortion. And the power line magnetic ring does not need to be grounded, and can be directly added to the cable.

Power line magnetic ring

Power line magnetic ring ^[1]

The power line magnetic ring is a commonly used anti-interference component in electronic circuits, which has a good suppression effect on high frequency noise. It is generally made of ferrite material. The power line magnetic ring solves the problem of high frequency interference suppression of power lines, signal lines and connectors, and has a series of advantages such as simple use, convenient, effective, small space, etc. Suppression of electromagnetic interference (EMI) is an economical, simple and effective method, which has been widely used in various military or civilian electronic equipment such as computers. The magnetic loop of the power line is used to suppress the common mode voltage, and it is not effective for the differential voltage. It is not only on the power supply head, but also on the phone cord that comes with IBM. It is reasonable to say that this should be on any cable that is often plugged in. Parallel cable, monitor cable, etc. For some reasons, such as a slender leakage or static electricity, there will be a large electrical difference between the host and the power supply. This voltage difference causes a very large shock current at the moment of plugging, which simply breaks down the component. This magnetic ring can effectively suppress the instantaneous surge current and allow the static electricity to be slowly released. When the plugging is completed, the voltage of the equipment at the two ends of the cable is consistent, this electromagnetic loop is essentially useless.

The longer the magnetic loop of the power cord, the better.
The tighter the magnetic ring aperture and the power supply passing through, the better.
When the low-frequency end is disturbing, it is recommended to wind the cable for 2 ~ 3 turns. When the high-frequency end is disturbing, it cannot be turned (because of the presence of distributed capacitance), and a longer magnetic ring is used.
Power line magnetic ring installation position: The magnetic ring installation position should be as close as possible to the interference power, that is, it should be close to the cable inlet and outlet.