- #1
Jonathan Mc
- 6
- 2
I'm trying to measure high voltages with a DAQ card. Obviously I'm going to have to attenuate the voltage, but I need to make sure that I can measure accurately (within 1%)
The code width of the DAQ is
Vcw = 20Vpp/2^16 = 305.176uV
For this code width to be within 1%, the minimum voltage I can read is 30.517mV (30.517mV +\- 1% or +\- Vcw)
Now here is where I need guidance. Is my thought process correct?
The maximum voltage that I will read is 800Vrms (1131.37Vp), and the minimum voltage I can read accurately is 30.517mVp
If I take the ratio of those two I calculate that I need about 37000 steps to measure 1131.37V.
The DAQ 2^16 (65536) steps.
So I have more than enough steps in order to keep from needing to amplify anything, yes?
And if the above is correct, realistically I will only mess with 0-120Vrms, which means that I will only ever see a little over 1v in the DAQ. But I feel like that is a waste of resolution. I MUST design the circuit to assume max input voltage of 800V though.
Any thoughts or suggestions?
The code width of the DAQ is
Vcw = 20Vpp/2^16 = 305.176uV
For this code width to be within 1%, the minimum voltage I can read is 30.517mV (30.517mV +\- 1% or +\- Vcw)
Now here is where I need guidance. Is my thought process correct?
The maximum voltage that I will read is 800Vrms (1131.37Vp), and the minimum voltage I can read accurately is 30.517mVp
If I take the ratio of those two I calculate that I need about 37000 steps to measure 1131.37V.
The DAQ 2^16 (65536) steps.
So I have more than enough steps in order to keep from needing to amplify anything, yes?
And if the above is correct, realistically I will only mess with 0-120Vrms, which means that I will only ever see a little over 1v in the DAQ. But I feel like that is a waste of resolution. I MUST design the circuit to assume max input voltage of 800V though.
Any thoughts or suggestions?