6100B/6105A
Users Manual
7-4
at the same rate or direction. High confidence can be taken from checking three phases
with the same measurement device. If the result from one phase appears different to the
others it is highly probable this item is the furthest from specification. If, however, all
results are similar, the accuracy of the measurement device should be considered.
If an adjustment is necessary, a cross check can be made to get more information about
the individual voltage and current channels. Though time consuming, this will give more
confidence with selection of any adjustments to be made:
1. Set the L1 channel voltage and current channels to the required levels.
2. Set L1 current phase angle to zero.
3. Set L2 voltage phase angle to zero.
4. Set L2 current amplitude to the required amplitude.
5. Set the L2 current phase angle to zero.
Now the L1 voltage and the L2 current are in phase. Measure power and record the result.
Repeat the process until all the current outputs have been measured with all voltage
outputs (six measurements). A simple analysis of the results will reveal which of the
voltage or currents is furthest from specification and which, if any, need to be adjusted.
7-7. Best Calibration Accuracy
7-8. Amplitude Measurements
Rigorous type testing of the 6100B has shown that when the phase and gain of each
voltage or current channel are correctly adjusted, all other specifications will be met.
Consequently, calibration of 6100B/6105A can be achieved with sinusoidal signals.
Users should be aware, however, that the Instrument is optimized for use with sampling
measurement instruments. Some rms-sensing meters have ac input bandwidths of many
MHz and cannot reject non-harmonic components. As a result, this type of instrument
may report amplitude values different from those obtained by sampling techniques.
Sampling systems using Fourier analysis have the advantage of extracting the signal of
interest from noise and yield accurate phase information.
7-9. Phase Measurement
Potentially, there are many ways of measuring amplitude and phase between Electrical
Power Standard output channels. The amplitude of voltage and current can be determined
independently but measurement of phase angle requires some form of comparison to be
made. Comparing the current and voltage outputs of a 6100B with a zero crossing
detection phase meter would provide phase information for that unit. But there are two
disadvantages to this method.
• Comparison of the zero crossing of two signals is subject to noise at the zero crossing
points; whereas sampling techniques get information from at least two points on the
waveform.
• Measuring only the phase angle between voltage and current of a single unit does not
allow independence of 6100B and 6105A calibration. Each 6101B auxiliary unit
would need to be calibrated with its Master 6100B unit for voltage to voltage
information.
If these disadvantages are acceptable for the calibration of a 6100B then phase
uncertainties in the order of 0.050 degrees are possible with zero-detection phase meters.
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