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10.2.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are “Enable” and “Disable”.
The operation of PQVPH can be described with a module diagram. All the modules in the
diagram are explained in the next sections.
Distortion
measure-
ment
Demand
calculation
BLOCK
ALARM
V_A_AB
V_B_BC
V_C_CA
GUID-477C2AE6-EE70-4A31-A71B-EE77DBFAFD0E V1 EN
Figure 528:
Functional module diagram
Distortion measurement
The distortion measurement module measures harmonics up to the 11th harmonic. The
total harmonic distortion THD for voltage is calculated from the measured harmonic
components with the formula
THD
V
V
k
N
k
=
=
∑
2
2
1
GUID-EF4F9D27-6E81-4697-B02C-EDBBD68CE9A8 V1 EN
(Equation 172)
V
k
k
th
harmonic component
V
1
the voltage fundamental component amplitude
Demand calculation
The demand value for THD is calculated separately for each phase. If any of the calculated
demand THD values is above the set alarm limit
THD alarm limit
, the
ALARM
output is
activated.
The demand calculation window is set with the
Demand interval
setting. It has seven
window lengths from "1 minute" to "180 minutes". The window type can be set with the
Demand window
setting. The available options are "Sliding" and "Non-sliding".
The activation of the
BLOCK
input blocks the
ALARM
output.
Section 10
1MAC059074-MB A
Power quality measurement functions
1038
615 series ANSI
Technical Manual
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