The grounding of shielding room is mainly for discharging electric charge or providing a reference potential. There are two purposes of grounding. One is to protect personal and equipment safety from lightning, electric leakage, static electricity and other hazards. This kind of ground wire is called protective ground wire and should be connected with the real earth. Second, in order to ensure the normal operation of equipment, it is called working ground wire. What are the grounding methods?
***Class: suspension grounding
1. The ground wire of the equipment is electrically insulated from the reference ground and other conductors, that is, the equipment is suspended;
2. In order to prevent the disturbance current on the chassis from being directly coupled to the signal circuit, the signal ground is intentionally isolated from the chassis, that is, the suspension ground of the unit circuit.
Type II: single point grounding
Single point grounding provides a common reference point for many connected circuits. Parallel single point grounding is simple, it has no common impedance coupling and low frequency ground loop problems, so there is no disturbance.
The third category: Multipoint grounding
Multi point grounding can avoid the problem of single point grounding at high frequency. Multi point grounding must be used in digital circuit and high frequency large signal circuit. Modules and circuits are connected by a number of short wires (< 0.1 λ) to reduce the common mode voltage generated by the ground impedance.
Class IV: hybrid grounding
Hybrid grounding includes both the characteristics of single point grounding and multi-point grounding.
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