3-wire combustible gas alarm connected to AI card; total card burnout – solution required
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The 3-wire combustible gas alarm is connected to an AI card, and the card keeps burning out. The wiring seems correct and the voltage is 24V; yet the card continues to burn out, with the negative terminal of the power supply also grounded
To add a signal isolation processor means using an isolation barrier
I guess your AI card is already powered, and the combustible gas alarm is powered externally; with these two power sources combined, either the meter or the card will get damaged.
In my case, the power for the combustible gas alarm comes from the instrument’s power supply; the signal wire goes to the isolation barrier, and from there it reaches the mounting unit. This setup has worked without any problems, and multiple alarms can share the same power cable.
A combustible gas detection transmitter should be used, which outputs a 4-20mA signal to the AI card. A three-wire combustible gas detector should be connected to the corresponding combustible gas alarm, which in turn is connected to a computer.
A safety barrier needs to be added. Prevent overload.
What was said on the 8th floor about combustible gases and safety barriers? At present, the vast majority of common combustible gases use catalytic combustion; they do not support intrinsically safe operation, and safety barriers cannot be installed! Only isolators can be used. An isolator and an isolated safety barrier (also known as an isolation gate) are not the same thing at all! A signal isolator and an isolated safety barrier are definitely not identical It cannot be confused. As for why the card overheats, most of the issues mentioned above have been taken into account; let’s go through them one by one.
9L is the correct answer: a barrier gate rather than a safety gate; gas detectors are basically explosion-proof
I would like to ask: could you explain what exactly this isolator does? Generally, on-site equipment operating at 220V requires isolation; does equipment operating at 24V also need isolation?