27
Table 1, below, shows a comparison of measurements made with
the
UNITEST Clamp Meter CHB 37
and those made with
conventional clamp meters that have average and peak value
functions:
Crest factor:
The crest factor is the ratio of the peak value to the RMS value of
a signal. This is important for RMS measurements (
UNITEST
Clamp Meter CHB 37
).Although the measured value may lie
within the chosen range, if the peak value of the signal is too high,
the
UNITEST Clamp Meter CHB 37
may be overmodulated and
give false readings.
4.8 MIN/MAX and peak value measurements
The MIN/MAX button can be used to find either the largest or the
smallest value of a series of measurements. Pressing the MIN/MAX
button activates first the MIN mode, so that the smallest value is
selected. Pressing it a second time changes to MAX mode, for the
largest value. Pressing the button a third time returns the instrument
to normal operation.
In the case of the
UNITEST Clamp Meter CHB 37
, you can find
peak values while making measurements of AC current or voltage
– simply select MAX mode, and start measuring. For example, a
typical application is finding the starting current of an AC motor.
Wave form
Wave form
Crest factor
RMS value
Rectified value
Display UNITEST
Clamp Meter
CHB 7
Deviation
Display UNITEST
Clamp Meter
CHB 37
Greek letter Xi
Deviation UNITEST
Clamp Meter CHB 37*
* more precise details of crest factor error are given in Section 6.0, Technical Data
Deviation
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