App-2
IM WT310E-01EN
•
Time
u(n)
•
i(n)
WP
WP+
WP
–
Measurement Function
Watt
hours
[Wh]
Methods of Computation and Determination
For information about the symbols in the equations see the notes.
q
q+
q
–
Integration time
[h:m:s]
Time
Time from integration start to integration stop
(Table 2/2)
Single-phase,
three-wire 1P3W
Three-phase,
three-wire 3P3W
Three-voltage, three-
current measurement 3V3A
Three-phase,
four-wire 3P4W
P1 + P2 + P3
P
Σ
[W]
P1 + P3
U
Σ
[V]
Wiring system
(U1 + U3) / 2
(I1 + I3) / 2
(U1 + U2 + U3) / 3
(I1 + I2 + I3) / 3
S1 + S3
(S1 + S2 + S3)
3
3
(S1 + S3)
2
3
S
Σ
[VA]
S1 + S2 + S3
Q1 + Q3
Q
Σ
[var]
Q1 + Q2 + Q3
Ampere
hours
[Ah]
rms
dc
I(n) is the nth measured current value.
N is the number of data updates.
The unit of time is hours.
I(n)
• Time
n = 1
N
1
N
N is the integration time sampling count. The unit of Time is hours.
WP is the sum of positive and negative watt hours.
WP+ is the sum of the above equations for all iterations where u(n) • i(n) is positive.
WP– is the sum of the above equations for all iterations where u(n) • i(n) is negative.
i(n)
• Time
n = 1
N
1
N
i(n) is the nth sampled data of the current signal.
N is the number of data samples.
The unit of time is hours.
q is the sum of i(n)'s positive and negative ampere hours.
q+ is the sum of the above equations for all iterations where i(n) is positive.
q– is the sum of the above equations for all iterations where i(n) is negative.
n = 1
N
1
N
I
Σ
[A]
COS
-1
(
)
P
Σ
S
Σ
WP
Σ
[Wh]
q
Σ
[Ah]
WP
Σ
WP1 + WP3
WP1 + WP2 + WP3
λΣ
ΦΣ
[°]
P
Σ
S
Σ
q
Σ
q1 + q3
q
1
+ q
2
+ q
3
WP–1 + WP–3
WP+1 + WP+3
WP–1 + WP–2 + WP–3
WP+1 + WP+2 + WP+3
WP–
Σ
WP+
Σ
q–
Σ
q
+
Σ
q
–1
+ q
–2
+ q
–3
q
+
1
+ q
+
2
+ q
+
3
q–1 + q–3
q
+
1 + q
+
3
Integration
Σ functions
Note
• u(n) denotes instantaneous voltage.
• i(n) denotes instantaneous current.
• n denotes the nth measurement period. The measurement period is determined by the synchronization
source setting.
• AVG[ ] denotes the simple average of the item in brackets determined over the data measurement
interval. The data measurement interval is determined by the synchronization source setting.
• PΣ denotes the active power of wiring unit Σ. Input elements are assigned to wiring unit Σ differently
depending on the number of input elements that are installed in this instrument and the selected wiring
system pattern.
• The numbers 1, 2, and 3 used in the equations for UΣ, IΣ, PΣ, SΣ, QΣ, WPΣ, and qΣ indicate the case
when input elements 1, 2, and 3 are set to the wiring system shown in the table.
Appendix 1 Symbols and Determination of Measurement Functions
