Could you design a circuit that allows remote shutdown of the pump from a DCS computer, but prevents remote startup of the pump, while allowing normal local startup and shutdown of the pump without any restrictions?
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I’m new to electrical work and just started working in the instrumentation department. My supervisor wants to implement this function and asked me if I could design it. The circuit requirements are as stated in the question: it is allowed to stop the pump remotely via the DCS computer, but starting the pump remotely is not permitted; local operation allows for normal start and stop of the pump without any restrictions.
The pump start/run digital signal is sent to the DCS; after reading this signal, the DCS allows for remote shutdown of the pump； Design the local pump start/stop circuit as required.
Such a chain logic can be set up
Is it acceptable to simply wire the DCS stop signal into the circuit for manual shutdown on-site? Is it still necessary to send the pump start signal to the DCS?
It is of course possible to connect the DCS pump shutdown contact in series in the on-site pump shutdown circuit as well. It’s just that the DCS side does not know whether the pump is running or stopped at the moment.
This question is really strange. Isn’t it enough to simply avoid remote startup and not have a startup button on the screen? Can the start control line not be pulled either?
It’s very simple: connect the DCS shutdown signal to the pump shutdown circuit; the DCS uses a normally closed contact for pulse output