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C3PO:
If the transducer output is actually 0 to 10 V, then there is signal conditioning somewhere in the transducer. This means there is power to the transducer. I will guess it is a straingage type.
This might be supplied with +/-12 and a common for reference. The 24 V could be the excitation to the bridge transducer followed by a differential amplifier referenced to the common wire. Also means a signal line. Possibly a total of 4 wires plus shield. This amplifier would have a low output impedance, there would be substantial shunt filtering capacitance on both + and - supplies to the common line. A lower supply voltage might be used, but you need a way to get the 0 to 10 V swing. It could be an unbalanced supply with the differential amplifier shifting the output to the 0 to 10 range.
Very likely the transducer bridge is balanced at about 0 pressure, but not necessary. Is there some additional wiring for bridge balancing?
I would physically disconnect the transducer from the pressure piping, but leave in the same physical position and insulated from the piping and connect the transducer housing to the shield and see if the noise is still present. This would be only after shorting the scope input at the scope to determine if noise was getting into the scope by some other path.
Provide more information on the transducer.
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