There are problems with the AO and isolation barrier of PCS7
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PCS7 has been in use for several months. Suddenly, one of the AO channels outputted 0 mA when connected to the isolation barrier; trying other alternative channels also resulted in a 0 mA output. The signal at the input of the MTL isolation barrier was measured, and the current of the AO signal was normal. As soon as the isolation barrier was connected, the output became 0 mA. The online monitoring hardware indicated that this channel was open-circuited. No open circuits were found in the external wiring, and the same issue occurred suddenly with other alternative channels as well. What could be the problem? Please help analyze it.
It seems there’s a problem with the isolation barrier; has a spare one been installed?
The channel has been changed, and accordingly the isolation shield has been replaced; it’s the same in this case as well
First, disconnect the external wires to determine whether it’s the isolation barrier or the card that’s damaged. From your description, it seems that both the isolation barrier and the AO card are damaged
The current is normal before it reaches the isolation barrier, but it becomes abnormal once it does reach the barrier; based on this, it can be concluded that the isolation barrier is faulty Try using a different isolation barrier that is currently working properly
First, try replacing it with a spare isolation gate; if that doesn’t work, then replace the AO channel. It might also be useful to try switching to a spare card.
First, disconnect the isolated output and connect a 250-ohm resistor to see if there is any voltage
It would be better if the original poster drew a diagram; it’s not very clear from what you’ve described. “The signal measured at the input of the MTL isolation barrier is normal, as is the current of the AO signal. But once the isolation barrier is connected, the output becomes 0 mA.” Did the original poster measure the current on the input side of the isolation barrier by removing it first? That’s why once the isolation barrier is connected, the output becomes 0; this output refers to the output side of the isolation barrier, right? ?