ABB 615 Series - Application

BLOCK
ALARM
Distortion
measure-
ment
I_A
I_B
I_C
Demand
calculation
GUID-E5EC5FFE-7679-445B-B327-A8B1759D90C4 V1 EN
Figure 526: Functional module diagram
Distortion measurement
The distortion measurement module measures harmonics up to the 11th harmonic. The
total demand distortion TDD is calculated from the measured harmonic components with
the formula
TDD
I
I
k
k
N
demand
=
=
∑
2
2
max_
GUID-9F532219-6991-4F61-8DB6-0D6A0AA9AC29 V1 EN (Equation 171)
I
k
k
th
harmonic component
I
max_demand
The maximum demand current measured by IA, IB, IC
If IA, IB, IC are not available in the configuration or the measured maximum demand
current is less than the Initial Dmd current setting, Initial Dmd current is used for
I
max_demand
.
Demand calculation
The demand value for TDD is calculated separately for each phase. If any of the calculated
total demand distortion values is above the set alarm limit TDD 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.
10.1.5 Application
In standards, the power quality is defined through the characteristics of the supply voltage.
Transients, short-duration and long-duration voltage variations, unbalance and waveform
distortions are the key characteristics describing power quality. Power quality is,
Section 10 1MAC059074-MB A
Power quality measurement functions
1034 615 series ANSI
Technical Manual