Reading Stray voltages

[faisaldin]

Hi everyone,

I want to read stray voltages in my cables(bunch of wires)  and acquire these values to display them on my PC. Is it possible that NI DAQ cards can acquire stray voltages as they do for normal voltages. I am very much confused about distinguishing, normal and stray voltages acquiring using same DAQ channel or more intuitively ADC.

Is it possible ????

If it is than let say i have a bunch of wires and i have to read stray voltages that can be existing in few of these wires, so i can read voltage readings on un energized (wires with no signals) that either they are carrying any voltages or not.....  but what if the same two wires are shorted and results in the voltage presence in unenergized wire.....

So how can i distinguish these voltages..... plz help me

[LVbum42]

I'm unsure about how to isolate stray voltages using our DAQ devices.  However there are things you should become familiar with in order to avoid/minimize their effect:

Field Wiring and Noise Considerations for Analog Signals:  https://www.ni.com/en/shop/data-acquisition/measurement-fundamentals/field-wiring-and-noise-consider...

High-Voltage Measurements and Isolation: https://www.ni.com/en/shop/data-acquisition/measurement-fundamentals/analog-fundamentals/isolation-t...

Regards,

Isaac S.

[johnsold]

If you go back to the fundamentals, there are no "stray" voltages. All voltages are defined by the circuit or by the electric and magnetic fields. The problem with wires in a cable which are not conductively connected to anything else is defining what the "circuit" is. You have primarily capacitive coupling and of course the loading effects of the measurement device to which you connect the wire(s).  If the wires are not connected so that currents do not flow, then inductive coupling is minimized.

Can you be more specific about exactly what your final goal is? Rather than asking vague questiosn about stray voltages, tell us that you are trying to verify that the cable does not have open or short circuits.  How many conductors are in the cable? Does the cable branch or does it have just two ends? Are there any circuit components such as resistors or diodes incorporated within the cable? What voltages and frequencies do you need to apply during the testing?

Lynn