6100B/6105A
Users Manual
7-12
7-16. Characteristics of the Calibration System
Transducers are used to convert the different 6100B output voltage and current levels to
nominally 800 mV. The DMM, a Fluke HP3458A/HFL with extended memory option, is
used on its 1.2 V dc range for all measurements to reduce the relative phase uncertainty
contribution from the DMM, i.e., errors in the DMM are the same for voltage and current.
For each measurement, the DMM is programmed to take 65,536 samples with an aperture
of 6 μs giving 18-bit resolution. Table 7-6 below shows samples per fundamental cycle
and the minimum samples at the highest settable harmonic frequency.
Table 7-6. Samples Per Cycle
6100B Fundamental
Frequency (Hz)
Sample Reference
Pulses per
Fundamental Cycle
Minimum Samples
per Cycle at
Maximum
Harmonic
Frequency
16 to 32 2048 20
32 to 69 1024 10
69 to 128 512 5
128 to 256 256 5
256 to 512 128 5
512 to 850 64 5
7-17. Transducers
The output from all transducers is 800 mV rms at full range. The switchable range
voltage transducer is built into a system switching control unit to provide full automation.
There are 6 voltage ranges each compensated by a parallel capacitive divider to
compensate for stray capacitance and the input capacitance of the system DMM. Voltage
divider phase uncertainty is typically 0.0002 ° at 60 Hz, 0.002 ° at 1500 Hz. Five special
co-axial shunts are used with values of 0.5 A, 2 A 10 A, 20 A and 80 A.
The shunts are designed to exhibit mutual inductance of 0.5 nH ± 0.5 nH. Shunts
typically have phase displacement error uncertainty of 0.0003 ° at 60 Hz and 0.013 ° at
1500 Hz. With the calibration system in a temperature-controlled environment the
transducers contribute less than 1 ppm to measurement uncertainty.
7-18. DMM Amplitude Error Contributions
DMM gain and bandwidth contribute to amplitude error. These errors are calculated and
combined with those of the transducers to provide amplitude corrections.
To Next Page
Loading...
