What impacts will a failure of the instrument UPS have?
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1. I have a gentle question: In petrochemical plants, does the DCS in the main control room use mains electricity? 2. In the event of a power failure in the mains supply, the UPS can continue to supply power to the DCS, preventing the computers from going black. Is my understanding correct? 3. If the mains power is normal but the UPS fails (there is only one UPS), will the computers in the control room go black, causing the equipment inside the system to stop operating? Will it affect DCS operations? Thank you; those who know please let me know. Looking forward to your input
1. The DCS in the control room of petrochemical plants generally does not use mains electricity directly, but is powered by a UPS (uninterruptible power supply) to ensure stability. 2. Your understanding is correct. If the mains power fails, the UPS can continue to supply power to the DCS, preventing the computers from turning off. 3. If the mains power is normal but the UPS fails (in the case of only one UPS), the computers in the control room may go black, which will affect the operation of the DCS and may lead to the shutdown of the equipment within the system. .
You need to find a power supply system diagram to take a look. Generally, a DCS system includes at least two power supplies, with one serving as a backup for the other – for example, mains power and power from the UPS output. Whether the mains power fails or the UPS stops working, the system will automatically switch to the other power source. Additionally, the UPS has at least two input sources: one from the mains power and the other from the battery. When the mains power is interrupted, it automatically switches to battery power; the duration of operation depends on the battery capacity and the size of the load.
1. A UPS typically has two power supply sources from the mains electricity (usually from two different power distribution circuits to ensure redundancy). One of these sources serves as the main power supply for the UPS, while the other acts as a bypass supply. When the UPS needs to be maintained, it switches to the bypass supply to power the DCS. Under normal operating conditions, if the main mains power supply fails, the UPS automatically switches to the batteries to supply power to the DCS. The duration for which the batteries can provide power depends on the capacity of the batteries and the level of load on the system; generally, this duration should be at least 30 minutes, though some requirements specify at least 1 hour (in such cases, more batteries are used) to fully meet the power needs of the DCS and SIS in case of a failure of the main mains power supply. 2. If the mains power is normal but the UPS is faulty, simply switch the UPS to bypass mode to supply power to the DCS. 3. DCS systems generally have two power supply sources: one from the mains electricity and one from a UPS, or they use two UPS units; in the event that one UPS fails, there is still another source of power available, either from the mains or from another UPS, so it is unlikely that this will cause the DCS system to stop operating (the probability is low)
It can be switched internally; use the one that has power
DCS systems generally use 1 mains power supply + 1 UPS supply, or dual UPS supplies, with both being in hot standby mode. Therefore, even if one of the power supply paths fails, it will not affect the system’s power supply; there will be no screen blackout, nor will it impact the operation of the DCS system. This is the purpose of using redundant power supplies.