Protective grounding
1. Lightning grounding is subject to lightning strikes (direct, induction or line introduction), in order to prevent damage to the grounding system. Often signal (weak) lightning ground and power (strong) lightning ground points, the reason for the distinction is not only because of the requirements of the grounding resistance is different, but also in engineering practice, the signal lightning ground is often attached to the signal on an independent ground, and the power supply lightning ground separate construction.
2. Working ground
Working ground is in order to make the system and the instrumentation connected to the system can operate reliably and ensure the accuracy of measurement and control and the grounding. It is divided into machine logic ground, signal circuit ground, shielding ground, in the petrochemical and other explosion-proof systems and intrinsically safe ground. Machine logic ground, also known as the host power supply ground, is the logic level of the computer within the negative end of the public **** ground, but also +5V and other power supply output ground. Signal circuit ground, such as the negative end of the transmitter ground, the negative end of the switching signal ground. Shield grounding (analog signal shield grounding).
3. Lightning grounding
Composed of a part of the lightning protection measures. Its role is to introduce the lightning current into the earth. Lightning protection of buildings and electrical equipment is mainly with lightning arrester (including lightning rods, lightning straps, lightning nets and lightning protection devices, etc.). One end of the lightning arrester is connected to the protected equipment, the other end of the grounding device.
4. shielding grounding
It is to eliminate the electromagnetic field on the human body is an effective measure, but also to prevent electromagnetic interference is an effective measure. High-frequency technology has been widely used in electrothermal, medical, radio broadcasting, communications, television and navigation, radar and so on.