【Daily Question 20090408】Please share, based on your on-site experience, the grounding fault conditions you have encountered
Thread Content
Please share your on-site experience by describing the grounding-related fault conditions you have encountered. Explain your manufacturing environment, system model, fault conditions, and solutions. We hope everyone will organize their thoughts freely and participate actively, with valuable insights from those who take part in the discussion being highly rewarded. Encourage originality
For acid production enterprises using Hilscher SmartPro systems, all temperature readings show the maximum value, while parameters such as pressure remain unaffected at 4-20 mA DC. Upon investigation, the cause was found to be: the positive terminal of one of the transmitter cables was in contact with the ground (the 24VDC power supply was not connected to anything, while its negative terminal was not grounded). ), the device is 24 VDC higher than the negative terminal of the power supply, which means that a high voltage is applied to both the positive and negative terminals of the temperature measurement channel, exceeding the common-mode rejection limit. This post was last edited by zhaohh3211 on 2009-4-8 11:11]
It happened in the 1990s; it was likely due to poor grounding, which caused groups of Zener-based safety barriers to burn out. The reason was that at that time, the instrument grounding and electrical grounding were completely separate; during on-site construction, a large potential difference arose between the two grounding electrodes due to the welding machine. I haven’t encountered such problems in recent years, as the principle of equipotential grounding is now more scientific and reasonable.
The DCS grounding in our company was poor, which caused an AC voltage of 9–13V to appear on the communication cables, resulting in cross-alarm signals on the dual-bus system. Once proper grounding was established, the fault disappeared. Everyone can take a look at this post: http://bbs.hcbbs.com/thread-422514-1-1.html
The grounding of the field transmitter causes the voltage across the meter to drop, resulting in an increase in the current in the entire circuit and an overhigh reading on the meter.