Individual distortion rate (U
harmonic current (Un or In) and the RMS value of the fundamental component (U
True root mean square value (TRMS): The square root of the sum of the squares of all components
forming the wave.
Harmonic content: The difference between the total voltage or current and the corresponding
fundamental value.
Harmonic distortion rate (THD): The ratio between the RMS value of the harmonic content of the
voltage and/or current and the value of the fundamental component.
Total demand distortion (TDD): Ratio between the effective value of the residual harmonic current
and the value of the maximum demand current.
Where I
, is defined as the average of the maximum demand currents in the last 12 months, measured
L
monthly. If this value is not available, the nominal line current can be used.
4.1.2.- MOST COMMON HARMONICS
lists the most common harmonic generator loads and the wave shape of the current they
Table 11
consume, as well as their harmonic spectrum.
114
% or I
n
% =
% =
% =
∗ 100
= �
= �
+
2
1
1
( ) % =
% =
∗ 100
1
= �
2
1
= �
+
+
2
2
2
( ) % =
1
2
3
Equation 2:True root mean square value
( ) % =
( ) % =
= �
+
+
+
2
2
2
1
2
3
( ) % =
( ) % =
�
+
2
2
( ) % =
Equation 3:Harmonic distortion rate.
�
+
2
2
( ) % =
( ) = [
( ) = [
=
−
( ) = [
∗
ℎ
=
% =
∗ 100
1
% =
∗ 100
1
% =
%): A ratio in % between the RMS value of the voltage or
n
= �
+
+
+
% =
∗ 100
2
2
∗ 100
2
2
% =
1
2
3
5
1
1
∗ 100
% =
∗ 100
Equation 1:Individual distortion rate
1
1
= �
+
+
+
+ ⋯
2
2
2
2
= �
+
1
2
3
5
2
2
1
2
+
+
+
+
+ ⋯
+
+ ⋯
2
2
2
2
2
2
2
2
1
3
2
5
3
5
�
+
+
2
2
= �
= �
+
2
2
3
2
2
1
1
2
1
= �
+
+
+
+
+
+ ⋯
+
+ ⋯
2
2
2
2
2
2
2
2
1
3
2
5
3
5
= �
�
�
+
+
1
2
2
+
+ ⋯
( ) % =
2
2
3
5
5
�
�
+
+
+
+
+ ⋯
1
2
2
2
2
2
2
2
3
2
3
5
5
1
1
( ) % =
+ ⋯
�
2
5
( ) % =
=
−
�
�
+
+
+
+ ⋯
+
+ ⋯
2
2
2
2
2
2
2
3
2
5
3
5
+
+ ⋯
2
2
1
1
3
( ) = [
5
∗
( ) % =
ℎ
1
=
=
=
−
=
−
+
+ ⋯
2
2
( ) = [
3
5
1
∗ () ]
∗
∗ () ]
∗
ℎ
ℎ
�
+
+
2
2
2
=
( ) = [
2
3
5
( ) % =
=
=
Equation 4:Total demand distortion.
∗ () ]
∗ 100
1
+ ⋯
1
∗ 100
1
% =
∗ 100
1
% =
∗ 100
+
+
+ ⋯
2
2
3
5
1
+ ⋯
2
+
+
+
+ ⋯
+
+
+ ⋯
2
2
2
5
2
2
2
3
5
3
5
+
+
+
+ ⋯
+
+
+ ⋯
2
2
2
2
2
+ ⋯
2
2
2
3
5
2
2
3
5
1
+ ⋯
�
+
+
+ ⋯
2
2
2
2
3
5
+
+
+ ⋯
2
2
2
2
3
5
1
1
�
+
+
+ ⋯
2
2
2
∗ ( ) ]
2
3
5
1
−
∗ () ]
∗
ℎ
=
−
+ ⋯
∗ () ]
∗
ℎ
=
AFQm IP54
or I
).
1
Instruction Manual