Measurement Setup
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Note:
Measurement accuracy is improved by minimizing the range for a given input signal.
3.4 Auto Voltage and Current range
The measurement range adjusts automatically according to the input signal, and uses same ranges as in Fixed range
mode. See
.
Adjustment of the range occurs when the following conditions occur:
3.4.1 Increasing range
• Urms or Irms exceeds 110% of the current range setting.
• When the crest factor is 3, and the peak voltage or current exceeds 330% of the range currently set.
• When the crest factor is 6, and the peak voltage or current exceeds 660% of the range currently set.
3.4.2 Decreasing range
• Urms or Irms is less than or equal to 30% of the current measurement range.
• The crest factor is 3. The value Upk or Ipk of the input signal is less than 300% of the range at the following level.
• The crest factor is 6. The value Upk or Ipk of the input signal is less than 600 % of the range at the following level.
Note:
The selected automatic range may change when the input is a random pulse. In this case, a fixed range should
be used.
3.5 Measurement interval
The measurement interval is the time during which data is taken. The fundamental frequency of the measured signals
restricts the measurement intervals that yield meaningful results. For example, measuring 10Hz with an interval of less
than the 0.5s setting will not yield stable results. The unit needs a number of cycles to be present to determine the
frequency, and measurement intervals are not synchronized to the input.
Note:
The scope timing parameters do not control the measurement interval.
• A cycle is determined by detecting zero crossings.
• Either positive, or negative going transitions of the synchronization source determine the measurement timing. If
the zero crossings do not occur within the set update interval, the entire interval is used for calculating the various
measurements. See
.
The choice of rising or falling transition is determined as that which gives the greatest amount of time.
• For peak value measurements (Ipk+, Upk-, etc
…
), the entire update interval is used. Measurements of Crest Factor,
as it is the Peak to RMS ratio, are also determined using the entire measurement update interval.
• The input signal used as the synchronization source is configurable, and determines the synchronization with the zero
point of that input signal. The overall interval of the voltage, current or data updating cycle may be selected as the
synchronization source.
Note:
The data updating cycle refers to the cycle used for calculating sampling data of the measurement function.
It is identical to the set value of the data updating rate.The slope refers to signal changes from low level to high level
(rising edge) or from high level to low level (descending edge).
