What Is The Difference Between PCB Single Point Grounding And Multi-Point Grounding
What is the difference between PCB single Point grounding and Multi-Point grounding
Grounding to prevent electrical shock or to protect the safety of equipment, power telecommunications and other equipment metal chassis or housing connected to the ground wire; To use the earth as a current circuit ground wire... In the power system, the neutral point of the equipment and the electrical device. A good electrical connection between a shell or bracket and a grounding device with a conductor is called earthing. The function of earthing is to protect the user from electric shocks, in addition to introducing unwanted current or noise into the earth. In the case of UPS, some UPS will mark the voltage between zero and ground wires to ensure that the product does not cause electrical damage to the human body.
1. Single point grounding
The low operating frequency (< 1MHz) uses a single point of grounding (i.e. a structural point in the whole circuit system is regarded as a ground reference point, and all ground connections are connected to this point). A safe grounding bolt is set to prevent the circuit coupling of common ground impedance caused by two-point grounding. The single-point grounding mode of multiple circuits is divided into two types: series and parallel. Because of the circuit coupling of common ground impedance caused by series grounding, it is better to adopt the single-point grounding mode of parallel connection in low frequency circuit. In order to prevent the interference of power frequency and other stray currents on the signal ground line. The signal ground wire shall be insulated from the power ground wire and the housing ground wire, and shall only be connected to the safety earthing bolts of the power ground wire, the housing ground wire and the earth wire connected to the earth (except floating ground type).
2. Multi-point grounding
The high operating frequency (> 30MHz) adopts the multi-point grounding type (I. E. in the circuit system). A grounding plate is used to replace each part of the circuit. Because the inductance of the grounding lead is proportional to the frequency and length, the common ground impedance will be increased when the working frequency is high. Therefore, the length of ground wire is required to be as short as possible, and the nearest low resistance value should be found as far as possible when multi-point grounding is adopted.
3. Hybrid grounding
When the length of the ground wire is less than 1/20 of the working signal wavelength, the single-point earthing mode is adopted, otherwise the multi-point earthing mode is adopted.