Section 4: Measure considerations
Model DMM7510 7½ Digit Graphical Sampling Multimeter Reference Manual
4-2
DMM7510-901-01 Rev. B / May 2015
When you set the time in relation to NPLCs, you set it as the number of power line cycles that should
occur during the measurement. Each power line cycle for 60 Hz is 16.67 ms (1/60); for 50 Hz, it is
20 ms (1/50).
The shortest amount of time or lowest NPLC value results in the fastest reading rate, but increases
the reading noise and decreases the number of usable digits.
The longest amount of time or highest NPLC value provides the lowest reading noise and more
usable digits, but has the slowest reading rate.
The Model DMM7510 has a nonlinear shape for its speed versus noise characteristics. The Model
DMM7510 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in
graph), the Model DMM7510 will make corrections for its own internal drift and will still be fast enough
to settle a step response of less than 100 ms.
Figure 134: Speed compared to noise characteristics
When using NPLCs to adjust the rate, frequency and period cannot be set. However, when using
aperture to adjust the rate, aperture can be set for both frequency and period.
