5.3 Energy parameters
SPM33 input and output of active and reactive energy, the maximum cumulative
to 99,999,999.9, display one decimal place. When the accumulated value
reaches to maximum, it will overturn automatically.
5.4 Harmonic parameters
SPM33 provides optional measurement of complete 31
st
harmonic for voltage
and current as well as their total harmonic content (THD) .
The data of harmonics are given according to the percentage of fundamental
harmonics and have one digit after the decimal point. That is to say, when the
value of the fundamental harmonic is fixed at 1000, it is 100.0% of the effective
value of the fundamental harmonic; others are by analogy.
THD refers to the total of higher harmonics except fundamental harmonics, and
it is calculated according to the following formula:
∑
=
=
=
n
i
i
i
X
THD
2
2
i
: Harmonic order.
i
X
: Percentage of the effective value of each harmonic to that of
the fundamental harmonic.
n
: Highest harmonic order, which should be 31 here.
【
Attention
】
：
Each harmonic and THD can be checked through display or
communication.
17