Wiring of three-wire instruments
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Dear poster, my instruments on site are three-wire type; how should I wire them in the DCS? Is there such a card or something similar in the DCS cabinet? If the cabinet has already been configured and installed, and additional wiring is added in a three-wire system, how can this be changed inside the cabinet? Thank you~
You haven’t specified what signals are associated with these three wires. If the three wires represent the signal positive, the common terminal, and the power positive, then you can simply connect them according to the instructions provided for the DCS card terminals!
The positive and negative of the power supply as well as the positive signal are used; the negative of the power supply and the positive signal are introduced into the DCS in a passive manner, while the positive and negative of the power supply are connected to 24VDC
Use three-wire wiring; do not use the 24V from the card. The 24V on the card has a very low output power, sufficient only to drive a two-wire meter; it generally cannot power a three-wire meter. Insufficient power supply usually results in extremely low output values from the meter. .