YOKOGAWA WT1800 User Manual page 108

Appendix 1 Symbols and Determination of Measurement Functions
Measurement Function
Integration time
[h:m:s]
Watt hours
[Wh]
Ampere
hours
[Ah]
q
q+
q–
Volt-ampere hours
WS[VAh]
Var hours
WQ[varh]
Wiring system
UΣ [V]
IΣ [A]
PΣ [W]
SΣ [VA]
QΣ [var]
PcΣ [W]
App-2
Methods of Computation and Determination
For information about the symbols in the equations,
see the notes at the end of page App-3.
Time
When the watt-hour integration method for each polarity is Charge/Discharge
WP
WP+
WP–
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.
When the watt-hour integration method for each polarity is Sold/Bought
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 positive power values at each data update interval.
WP- is the sum of the negative power values at each data update interval.
rms,
mean,
r-mean,
ac
dc
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.
S(n) is the nth measured apparent power value. N is the number of data updates.
The unit of time is hours.
Q(n) is the nth measured reactive power value. N is the number of data updates.
The unit of time is hours.
Single-phase,
three-wire
1P3W
(U1 + U2) / 2
(I1 + I2) / 2
TYPE1,
S1 + S2
TYPE2
TYPE3
TYPE1
TYPE2
TYPE3
Time from integration start to integration stop
N
[
1
{
u(n)
N
n = 1
N
[ 1
{
u(n)
N
n = 1
N
1
I(n) • Time
N
n = 1
I(n) is the nth measured current value.
N is the number of data updates.
The unit of time is hours.
N
1
i(n) • Time
N
n = 1
N
1
S(n) • Time
N
n = 1
N
1
Q(n) • Time
N
n = 1
Three-phase, three-wire
Three-phase,
three-wire
3P3W
P1 + P2
3
(S1 + S2)
2
2 2
PΣ + QΣ
Q1 + Q2
2 2
SΣ - PΣ
Q1 + Q2
Pc1 + Pc2
]
}
i(n) Time
• •
]
}
i(n) Time
• •
Three-phase,
with three-voltage,
three-current method.
3P3W(3V3A)
(U1 + U2 + U3) / 3
(I1 + I2 + I3) / 3
P1 + P2 + P3
3
(S1 + S2 + S3)
S1 + S2 + S3
3
Q1 + Q2 + Q3
Q1 + Q2 + Q3
Pc1 + Pc2 + Pc3
(Table 2/3)
four-wire
3P4W
IM WT1801-03EN