20mV DC offset noise in a 30 mtrs long wire

[kumecepent]

HI All,

I have connected a 30 mtrs long wire with a sensor at it one end and other end is connected to my measurement system. I am getting 0mV at sensor end and other end of the wire is 20mV DC noise. Please help me to solve this issue. I am using 2 core AWG 22 twisted pair shielded PTFE cable. I have grounded -ve terminal of a 24V SMPS, 0V terminal of a ±15V linear power supply and chassis ground and main 230VAC's EARTH terminal. All are these terminals are shorted.

 

[FoxyRick]

30m is a long wire. May I suggest differential signalling? Optical fibre would be better, but add complexity which might not be viable at the sensor.

 

[kumecepent]

I am sorry. Optical fibre is not possible in this case.

 

[mtwieg]

DC offsets are not "noise." It's probably the result of ohms law: DC current flowing through a wire with a finite resistance.

A more detailed description of the sensor and the connections would help.