Hioki HITESTER 3184, Instruction Manual

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Chapter 3 Basic Operating Principle
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3.3 Crest-Factor
In measuring instruments, the dynamic range of the
meter circuit is expressed as a crest-factor.
In
measurements where peak-values are high relative to rms
value, selecting a suitable range for the rms value will
likely result in the waveform peaks exceeding the
dynamic range of the signal.
Crest-factor is the ratio of
peak-value to rms value, defined as follows.
Peak-value
Crest-factor =
Rms value
For these instruments, crest-factor is as follows.
AC voltage (V
12
, V
32
): Two or less at full-scale
AC current (A
1
, A
3
): Two or less at full-scale
Single-and 3-phase active power (W): Same as voltage and
current.
For example, when measuring AC current in the Lo range
with the 3184, maximum display value(full-scale) is 2 A,
so maximum allowable peak-value input (maintaining
accuracy) is as follows.
Peak-value = rms value
× crest-factor
= 2 [A] × 2 = 4 [A]
When measuring AC voltage in the Hi range full-scale is
500 V, so 500 [V]
× 2 = 1000 [V] (peak-value)
The overcurrent and overvoltage warning indicators will
light when input value exceeds the peak-value in the
table on the next page.