Should a safety barrier be added to the simulation card?
Thread Content
My ABB AC800M is equipped with 1 AI880, and it is connected to 6 PHONIX magnetostrictive level gauges as well as level transmitters; an external power supply of 24.5VDC is used. Three of them are normally in a state of full liquid level; the current values of their level transmitters at full level are 20.40 MA, 20.61 MA, and 20.31 MA respectively, while the current values of the other three level transmitters are all within the normal range. Currently, the control panel is showing an error alert of AI880 CHANNEL ERROR. Upon inspection, the operating voltage of all 6 level transmitters has dropped below 16 VDC, and the control panel indicates that these six level transmitters are disconnected ； Sometimes, a fault occurs in N(1~5)/6 of the level transmitter, causing the control panel to indicate a disconnected status. I would like to ask: in such a situation, can adding a safety barrier increase the operating voltage of the level transmitter? Can it be ensured that the level transmitter has a proper operating voltage?
The safety barrier is a component of the intrinsically safe explosion-proof system; it is not used to increase the power supply voltage of the field transmitters. When the level transmitter is out of range and the output current exceeds the specified value, the DCS considers it to be an open circuit; this is a normal phenomenon. It is necessary to identify the cause of the out-of-range condition and address it. When the loop current is high, the voltage drop across the wires increases, which in turn reduces the supply voltage at the field instruments; this is still caused by exceeding the specified range. It is also possible to use cables with a larger cross-sectional area to reduce the loop resistance, thereby ensuring that the power supply for the instruments on site remains within the normal range.
It is not used to increase the power supply voltage of the field transmitter. When the level transmitter is out of range and the output current exceeds the specified value, the DCS considers it to be an open circuit; this is a normal phenomenon. It is necessary to identify the cause of the out-of-range condition and address it. When the loop current is high, the voltage drop across the wires increases, which in turn reduces the supply voltage at the field instruments; this is still caused by exceeding the specified range. It is also possible to use cables with a larger cross-sectional area to reduce the loop resistance, thereby ensuring that the power supply for the instruments on site remains within the normal range.
Okay, thank you for the advice. I’m not very familiar with safety barriers since I’ve never used them before. I’m going to check now for the reason of exceeding the range, to see if it’s due to the actual range of the level transmitter not matching the range specified in the program.
Okay, thank you for the advice. I’m not very familiar with safety barriers since I’ve never used them before. I’m going to check now for the reason of exceeding the range, to see if it’s due to the actual range of the level transmitter not matching the range specified in the program.