1 The shell, instrument basin, cabinet, box, box, cable tray, protection, support, base and other normal non-live metal parts of electrical instruments, which may carry dangerous voltage due to insulation damage, shall be protected by grounding. For local instruments and switches with power supply voltage not higher than 36V, protective grounding may not be required when there is no special requirement in the design documents.
2 In the non-explosive area of the metal plate, the button installed on the board, signal lights, relays and other small low-voltage electrical appliances metal shell, when the metal plate has been grounded, good contact, do not do protective grounding.
3 The instrument protective grounding system shall be connected to the protective grounding network of low-voltage electrical equipment in electrical engineering, and the connection shall be firm and reliable, and shall not be grounded in series.
4 The grounding resistance of protective grounding shall comply with the provisions of the design documents.
5 The cable tray and cable protection pipe installed on the building can be repeatedly grounded.
6 The instrument and control system shall be grounded for work, including signal loop grounding and shield grounding, as well as intrinsically safe circuit grounding for special requirements. The connection mode and grounding resistance value of the grounding system shall comply with the provisions of the design documents.
7 The signal loop grounding and shielding grounding of the instrument and control system shall share a common grounding device.
8 There shall be only one signal loop ground point for each instrument loop, unless an isolator is used to isolate the DC signal loop between the two grounds.
9 The grounding point of the signal circuit shall be on the display instrument side. When the grounding type thermocouple and the instrument with grounding detection element are used, the grounding point shall not be on the display instrument side.
10 The shielding layer of instrument cable wires shall be grounded on the side of the instrument panel cabinet in the control room. The shielding layer of the same circuit shall have reliable electrical continuity and shall not be floated or repeatedly grounded.
11 When interference prevention is required, the spare core wire in the multi-core cable shall be grounded at one point, and the spare core wire of the shielded cable and the cable shielding layer shall be grounded on the same side.
12 All kinds of grounding of each circuit in the instrument panel, cabinet and box shall be led to the grounding bus bar or grounding terminal board by their respective grounding branch lines, and the grounding main line shall be led out by the grounding bus bar or grounding terminal board, and then connected to the grounding main line and grounding electrode. The grounding branch lines, busbars or terminal boards shall be insulated from each other at the non-connection.
13 The wiring of the grounding system shall be copper-core insulated wires or cables, fastened with galvanized bolts, and the grounding bus bars in the instrument panel, cabinet and box shall be copper and fixed with insulating brackets. Welding shall be adopted between main grounding line and grounding body.
14 The intrinsically safe circuit itself shall not be grounded unless otherwise specified in the design documents. When a diode safety barrier is used, its ground shall be connected to the common terminal of the DC power supply.
15 The color of the ground wire shall be in accordance with the design documents, and green and yellow signs shall be set.
16 The anti-static grounding shall be in accordance with the regulations of the design documents, and can be carried out simultaneously with the anti-static works of equipment, pipeline and electricity.