DO point plus relay
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Are the normally open contacts at the DO point, which control the shut-off valve and the start/stop of the pump via relays, active or passive?
The system between the relay and the solenoid valve for the shut-off valve is powered on; as for the connection between the relay and the electrical components, it is determined by the two relevant specialists within the company, and it is our electrical specialists who handle the power-on process.
In my opinion, for the DI and DO points in electrical engineering applications, it is recommended to use isolation relays in DCS systems to prevent 220V voltage from reaching the DCS and causing damage to the circuit cards.