YOKOGAWA WT500 User Manual page 322

Appendix 1 Symbols and Determination of Measurement Functions
Measurement Functions
Used in Normal
Measurement
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
US [V]
IS [A]
PS [W]
SS [VA]
QS [var]
App-2
Methods of Computation and Determination
For information about the symbols in the equations,
see the notes at the end of page 3.
Time
When the watt-hour integration method for each polarity is Charge/Discharge
WP
WP+
N is the integration time sampling count. The unit of Time is hours.
WP–
WP is the sum of positive and negative watt hours.
WP+ is the sum of the values when u(n)
WP– is the sum of the values when u(n)
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,
RMEAN,
AC
DC
i(n) is the nth sampled data of the current signal.
N is the number of data samples.
q is the sum of positive and negative ampere hours.
q+ is the sum of the values when i(n) in the above equation is positive.
q- is the sum of the values when i(n) in the above equation is negative.
The unit of time is hours.
S(n) is the nth measured apparent power value, and N is the number of data updates.
The unit of Time is hours.
Q(n) is the nth measured reactive power value, and 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,
with three-voltage,
three-wire
three-current method.
3P3W
3P3W(3V3A)
P1 + P2
3
(S1 + S2)
2
2 2
PS + QS
Q1 + Q2
2 2
SS - PS
Q1 + Q2
]
}
i(n) Time
•
i(n) in the above equation is positive.
i(n) in the above equation is negative.
]
}
i(n) Time
• •
Three-phase,
four-wire
3P4W
(U1 + U2 + U3) / 3
(I1 + I2 + I3) / 3
3
(S1 + S2 + S3)
S1 + S2 + S3
3
Q1 + Q2 + Q3
Q1 + Q2 + Q3
(Table 2/3)
P1 + P2 + P3
IM 760201-01E