10 tips and regulations for grounding instruments

Grounding in the instrumentation industry is also studied. Only correct grounding can ensure measurement accuracy and the safety of people and equipment. Here are ten tips to help you become better grounded.

1. The AC power supply of the control system should come from a separate system and be separated from other equipment and uses;

2. The power supply should take into account the impact of the initial current when designing and be able to withstand at least 10 cycles;

3. The AC grounding of the control system should be established on an isolation transformer or UPS, or nearby;

4. The AC power supply of the control system workstation should use a dedicated socket;

5. When there are several I/O interface adapters connected to the power supply of field equipment, isolation barriers should be used;

6. The AC power supply of the control system should be supplied by an isolation transformer or UPS;

7. When AC and DC inputs are connected to the same terminal strip, the terminal strip must be marked with appropriate warning labels;

8. The AC ground wire should be the same size or one size larger than the current-carrying wire;

9. Reserve an extra wire or use a terminal box to provide a test point.

10. The resistance of the grounding system must be tested to ensure that the grounding can meet the requirements of the control system manufacturer for electromagnetic wave testing.

Instrument grounding regulations:

1. The instrument grounding system is divided into two types: protective grounding and working grounding. Grounding plays a very important role in suppressing interference signals, ensuring measurement accuracy, protecting personal and equipment safety, and ensuring high and stable production.

2. The protective grounding is connected to the grounding grid of the electrical system of the device, and the general grounding resistance is ≤4Ω.

3. Working grounding includes signal loop grounding, shielding grounding and intrinsically safe system grounding. The signal loop grounding and shielding grounding are connected to the instrument system grounding grid, and the grounding resistance conforms to the manufacturer's standards; when the intrinsically safe grounding system is set up independently, the distance between the individual intrinsically safe grounding electrode and the grounding grid of the device's electrical system or other grounding grids Distance ≥5.0m, grounding resistance ≤1Ω or comply with manufacturer standards.

4. The cable shielding layer should be grounded at one end of the control room and connected to the grounding bus of the instrument equipment. The signal shielding layer should remain continuous throughout the entire cable connection.

5. The grounding wire is made of multi-strand copper core stranded wire and is connected by crimping method.

6. The color of the insulation sheath of the grounding wire should be yellow and green, and there should be signs on both ends to indicate the grounding type.