MIB Installation Instructions and Reference Handbook
DEIF A/S
Page 38 of 50
Harmonic parameter:
Total harmonic distortion: This factor is often used to express the power
quality of the power system. The formula is as follows:
In the formula, U1 is RMS value of the voltage fundamental and Uh is RMS
value of the voltage harmonic with order n.
Each harmonic rate: The percentage of each harmonic divided by
fundamental.
Demand: Demand of total power and reactive power of system, demand of
three-phase current. The demand statistics method in MIB is sliding
windows. The total sliding windows time can be chosen from 1 to 30
minutes. Each window slides once per minute.
Example: The sliding window time is supposed to be three minutes. If
average power of the 1
st
minute is 12, 14 of the 2
nd
minute and 3
rd
minute is
10.
Result of the total power demand the last three minutes is:
(12+14+10)/3 = 12 at the end of the 3
rd
minute. If another minute passed,
the average power of the minute is then 9, then the total power demand of
the last three minutes is (14+10+9)/3 = 11 at the end of the 4
th
minute.
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