保护接地适用于不接地电网。这种电网中，凡由于绝缘破坏或其他原因而可能呈现危险电压的金属部分，除另有规定外，均应接地!
Protective grounding is applicable to ungrounded power grid. In this kind of power grid, all metal parts that may present dangerous voltage due to insulation damage or other reasons shall be grounded unless otherwise specified!
把正常情况下不带电，而在故障情况下可能带电的电气设备外壳、构架、支架通过接地和大地接连起来叫保护接地。保护接地的作用就是将电气设备不带电的金属部分与接地体之间作良好的金属连接，降低接点的对地电压，避免人体触电危险。
Connecting the shell, frame and bracket of electrical equipment which are not electrified under normal conditions and may be electrified under fault conditions with the earth through grounding is called protective grounding. The function of protective grounding is to make a good metal connection between the uncharged metal part of electrical equipment and the grounding body, reduce the contact voltage to the ground, and avoid the risk of electric shock.