NetDAQ Users Manual

Specifications
2645A Specifications A
A-19
2645A AC Voltage Measurement Specifications A-23.
Tables A-27 to A-29 provide 2645A specifications for the ac voltage measurement
function.
Table A-27. 2645A AC Voltage General Specifications
Specification Characteristic
Input Impedance 1 MΩ in parallel with 100 pF
Maximum Crest Factor 3.0 Maximum
2.0 for rated accuracy
Crest Factor Error For non-sinusoidal input signals with crest factors
between 2 and 3 and pulse widths ≥100 µs, add
0.2% to the accuracy specifications.
Common Mode Rejection 80dB minimum at dc, 50 Hz/60 Hz ±0.1%, 1 kΩ
imbalance, Slow Rate
Maximum Input Voltage The lesser voltage of:
30V ac rms from any input terminal to earth.
30V ac rms from any terminal input to any other
input terminal.
Maximum Volt-Hertz Product 2x10
6
Volt-Hertz product on any range, normal
mode input.
1x10
6
Volt-Hertz product on any range, common
mode input.
Temperature Coefficient Linear interpolation between 2 applicable points for
temperatures between 28ºC and 60ºC, or -10ºC
and 18ºC, e.g., if the applicable specification at
28ºC is 2% and the specification at 60ºC is 3%,
then the specification at 40ºC is
(3%-2%)x(40-28)/(60-28)+2%=2.375%.
Accuracy at -20°C Multiply the -10°C to + 60°C accuracy specification
by 2. After 1 hour warm-up. For accuracy between
-10°C and -20°C, interpolate linearly.
DC Component Error The presence of a dc voltage will cause an
indeterminate error in the reading of the ac voltage
on the input.