Issues regarding the central control DCS switch module
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The pump shutdown circuit is connected to the contactor on site, and that contactor is linked to an inverter. I activated the shutdown module, but the pump on site did not stop (I had to click the shutdown button several times before it stopped). What could be the reason? Is there a problem with the program?
One reason is that the distance between the lines might be large, resulting in excessive voltage drop； Secondly, there is distributed capacitance, which results in a lower signal potential being transmitted to the inverter
At the on-site contactor, the circuit voltage should be 220AC. If the circuit is long, there will be residual voltage, causing the coil not to release. A basic solution: delay the stop signal, for example by 5 seconds. Intermediate solution: Add RC components to absorb the residual voltage. Advanced solution: DO 24VDC output; a 24V relay converter is added in the on-site cabinet before connecting to the contactor. There is a note in API-552 stating that for circuits controlled via AC, it is recommended that the maximum distance not exceed 330 meters. Additionally, on the old on-site motor control panels, there was also interference between the start/stop indicator lights: for example, when the stop light turned on, the operation light would also turn “half on”. The solution is to separate the two cables to avoid interference between them.
The low-level \ud83d\ude04 used