【Weekly Question 20090706】Please share your knowledge regarding the installation requirements and on-site conditions of control systems you are familiar with

AB LOGIX5000 grounding requirements (1) Ground resistance of the instrument system

The installation of the computer control room shall be carried out in accordance with relevant specifications; the standard \"HG-T20508-2000 Requirements for Control Room Design\" can be referred to, and each DCS system also has its own specific installation requirements. However, it is quite difficult to meet all the requirements; one can proceed with the installation based on the actual conditions of one’s own company. But the following points are necessary: 1. Control room ambient temperature ； 2. The control room is relatively sealed to effectively prevent corrosive gases from entering. If working in areas with high levels of gas, an air purification device should be installed ； 3. EMI protection: It should not be placed near high-voltage distribution rooms, nor too close to frequency converters ； 4. Power supply requirements: It is preferable to have dual power supplies, with these two circuits coming from different power distribution rooms. 5. Insulation layer: Anti-static wooden flooring should be installed as well. 6. . . . .

The Zhejiang University Zhongkong JX-300X requires that the working environment in our factory meet the following standards: temperature between 15℃ and 30℃, humidity between 45% and 80%; dew formation is not allowed under any circumstances. The rate of temperature change should be ≤5℃/h, and the vibration amplitude…

Every company sets forth certain requirements for standardized, ideal environmental conditions. Unfortunately, many actual sites fail to meet these requirements. Does that mean DCS is no longer useful? It still needs to be used; there are still differences in such situations. For example, in sulfuric acid plants and urea plants where there is corrosive air, the DCS cards need to meet G3 certification standards. In other words, it is the environment that imposes requirements on DCS, rather than DCS imposing requirements on the environment. DCS requires an environment free of corrosive gases, but if that condition isn’t met, what’s the point? In such cases, Honeywell’s PKS C300 + C-IO can meet G3 standards, and ABB’s AC800F also offers enhanced cards that comply with G3 standards. Foxboro seemingly doesn’t have G3 certification, but its IAs feature robust enclosures that I believe are even better than those of other products with G3 certification; both achieve corrosion resistance, but Foxboro’s card design is more suitable for this purpose. Similarly, when ABB was used in a chemical plant in the southwest, the Amro series of IO stations were employed, all with stainless steel enclosures and an IP65 (almost IP67) protection rating. Even without G3 certification, they proved to be more reliable than many products with G3 certification. In some environments where flammable gases may leak, it’s not appropriate to have a dedicated safety control room. In such cases, fully intrinsically safe IO devices are very suitable—Siemens ET200iSP, ABB S900, and Turck EXCOM are all good choices, while Honeywell, ABB, and Yokogawa are clearly not suitable. Another example is applications on ships; let’s call them DCS systems for now. These systems require cards that are waterproof, pressure-resistant, and corrosion-resistant. Even being hit by shells or subjected to severe vibrations from large waves shouldn’t cause the CPU to stop working. With mainstream systems, even if the CPU isn’t directly hit by a shell but only experiences intense vibrations, at least 7 out of 10 systems will stop functioning. Some systems require the CPUs to be placed separately, one at the bow and one at the stern, connected by fiber optics. Systems like HW C300, Yokogawa CS3000, and Emerson DeltaV simply cannot meet these requirements. If the CPUs are placed at the bow and the bow is damaged or flooded, even with 8 CPUs in hot standby redundancy, everything will still be ruined. In such situations, the advantages of Siemens PCS7 and HW C200 become evident. After all this talk, the point is that standard DCS systems are designed to work in standard environmental conditions. Most DCS systems can handle normal issues such as grounding problems, interference, voltage fluctuations, vibrations, temperature, and humidity. However, each company has its own features, and in many special environments, their performance varies. So what I’m saying is that it’s often the environment that determines what conditions a control system must meet.

I came to learn*. All I know is temperature, power supply, interference, and the floor

Technical requirements for the peripheral environment of the Hilscher MACS system: 1. Power supply – The system control station can be powered by two separate 220V, 50Hz single-phase AC power supplies simultaneously. 2. Grounding: Add grounding leads for the new cabinet and connect them to the grounding busbars of the existing cabinet; ensure that the grounding resistance is less than or equal to 4 ohms. 3. Environmental requirements: Ambient temperature: 0°C to 40°C; Relative humidity: 40% to 90%; Atmospheric pressure: 86 KPa to 106 KPa. Intense mechanical vibrations and strong magnetic fields are not allowed in the control room. To meet the requirements of the working environment, the control room should be kept clean and protected from dust. The doors and windows of the control room must be properly sealed, and it is recommended to install air conditioning in the control room.