Fluke 6105A - DMM Amplitude Phase Contributions; Voltage to Voltage Phase Uncertainty; Current to Voltage Phase Uncertainty; Overview of Adjustment

Calibration
Overview of Adjustment 7
7-13
7-19. DMM Amplitude Phase Contributions
The various phase error contributions of the DMM considerably exceed that of the
transducers. Some of these contributions cancel for current to voltage phase
measurements but not in voltage to voltage measurements for multiphase systems. The
main systematic contributions to phase error from the DMM are bandwidth, aperture and
trigger delay. Table 7-7 shows the phase displacement uncertainties achieved in the Fluke
system once DMM phase errors are compensated.
Table 7-7. DMM Phase Error Uncertainty (Degrees)
Frequency
Bandwidth
Uncertainty
Trigger
Uncertainty
Aperture
Uncertainty
Combined
uncertainty
Expanded
Uncertainty
(k = 2)
60 Hz 0.0004 0.0008 0.0000 0.0009 0.0018
6 kHz 0.0441 0.0786 0.0001 0.0901 0.1802
7-20. Voltage to Voltage Phase Uncertainty
In Fluke service center systems errors are compensated by the application of corrections.
The uncertainty due to the short-term stability of the DMM and measurement noise, plus
the uncertainty due to voltage and current transducers must be combined with these
values but these at typically 0.00023 ° are negligible. Thus the voltage to voltage phase
calibration uncertainty for a 6100B and 6101B calibrated at different service centers will
fall within the uncertainties estimated in Table 7-7 above.
7-21. Current to Voltage Phase Uncertainty
The phase of the current output of a 6100B or 6101B is specified relative to the voltage
channel of the same instrument. By using the same DMM to measure both voltage and
current against the common Sample Reference signal means all DMM related
uncertainties other than short-term stability and measurement noise cancel. The
remaining contributions (typically 0.00023 °) are combined with transducer contributions
giving a total expanded system uncertainty of 0.0008 ° for current to voltage phase.
7-22. Overview of Adjustment
The steps required to calibrate at an adjustment point are enter the calibration mode then,
for each calibration point:
• Select the instrument configuration required
• Determine the 6100B error by measurement
• Initiate the adjustment
The 95
th
harmonic amplitudes are outside the normal range for harmonics and can only be
set in the calibration adjustment mode. The final step is to check the residual error is
within acceptable limits and report the value to the calibration certificate.