Operation Principle - ABB 615 series Technical Manual

Section 10
Power quality measurement functions
10.2.4
1038

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.
V_A_AB
V_B_BC
V_C_CA
BLOCK
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
N 2
V
∑
2
k k
=
THD
=
V
1
GUID-EF4F9D27-6E81-4697-B02C-EDBBD68CE9A8 V1 EN
V
k th harmonic component
k
V the voltage fundamental component amplitude
1
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.
Distortion
Demand
measure-
calculation
ment
1MAC059074-MB A
ALARM
(Equation 172)
615 series ANSI
Technical Manual