Hioki 3196 - Page 225

Appendix
219
Out of crest factor
The crest factor expresses the size of the dynamic range of input on
the measurement device and can be defined with the following expres-
sion.
Crest factor = crest value (peak value)/RMS value
For example, when measuring a distorted wave with a small RMS and
a large peak on a measurement device with a small crest factor,
because the peak of the distorted wave exceeds the detection range
of the input circuit, an RMS or harmonic measurement error occurs.
When you increase the measurement range, the peak does not
exceed the input circuit’s detection range, but because the resolution
of the RMS decreases, measurement errors may occur.
With this device, because the voltage input area has a crest factor of 3
and the current input area has a crest factor of 4, the peak can be
obtained even for large distorted waves.
However, when a measurement that exceeds the peak is input, it
appears outside the crest factor and you are informed of data that con-
tains measurement errors.
100
50 2
50
0
-50
-100
A
Measurement is not
possible
Measurement is not
possible
A measurement device with a small crest factor
(When the crest factor is 2 for a 50 A range)
200
50 2
50
0
-50
-200
[A]
16-bit resolution
Crest factors of the 3196
(The crest factor of the current input area is 4.)