When the device loses power
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When the device loses power, does the electrical signal to the instruments also get interrupted? Will the shut-off valves and pneumatic control valves switch to an emergency safety mode? Thank you all for your guidance
Check the power supply system to see if there is a UPS or other backup power source. If not, as you said.
Typical instruments are equipped with a UPS backup power supply to provide support for a certain period of time, but they still cannot function in the event of a prolonged power outage. Apart from electrical issues, a drop in the pressure of the instrument air can also cause the situation you mentioned.
Check if there is a UPS or other backup power supply. If not, as you said.
It depends on the security strategy adopted during device design. If the instrument air is cut off at the same time, the pneumatic device will return to a safe state ； If the instruments do not have an uninterruptible power supply UPS, all of them will stop working ； With the instrument air supply continuous and the instruments equipped with uninterruptible power supplies, all instruments can remain operational for a period of time (usually several dozen minutes).
The safety instrument system must be powered by a dual-UPS supply.
Every device experiences various issues such as voltage fluctuations or power outages, but as a safety control system, a UPS is essential for the system; it is usually redundant, and measures such as regular discharge switching are necessary.
The company I work for has experienced multiple instances of a complete power outage across the entire facility. At night, there is no power for the lighting of the pumps and machinery on site; only the instruments are powered by UPS systems. The gas used for these instruments comes from storage tanks, which can provide supply for over a dozen hours. The DCs operation station, monitoring station, control station, etc. can all operate for over ten hours, but the 220V solenoid valves do not have UPS power supply