Schweitzer Engineering Laboratories SEL-734 - Page 83

4.37
Date Code 20090730 Instruction Manual SEL-734 Meter
Metering
Metering Calculations
Per-Phase Active
Power (W)
This calculation is the numerical approximation of IEEE 1459-2000, 3.1.2.3.
Form 9 (3-element meter)
x = a, b, or c
Form 5 (2-element meter)
Per-phase values are not calculated for delta.
Three-Phase Active Power (W)
Form 9 (3-element meter)
P = P
a
+ P
b
+ P
c
Form 5 (2-element meter)
This calculation is the numerical approximation of IEEE 1459-2000, 3.1.2.3,
applied to the two-elements of a Form 5 meter.
Per-Phase Apparent
Power (VA)
S
x
= V
x
• I
x
This calculation is the equivalent of IEEE 1459-2000, 3.1.28.
Form 9 (3-element meter)
x = a, b, or c
Form 5 (2-element meter)
Per-phase values not calculated for delta
Three-Phase Apparent Power (VA)
Form 9 (3-element meter)
S = S
a
+ S
b
+ S
c
This calculation provides arithmetic apparent power.
where:
N = Number of samples
v
x
(n) = Array of periodic voltage samples
i
x
(n) = Array of periodic current samples
P
x
v
x
n() i
x
n()•
0
N 1–
∑
N
------------------------------------------=
P
v
ab
n()
0
N 1–
∑
i
a
n()•
N
----------------------------------------------
v
cb
n()
0
N 1–
∑
i
c
n()•
N
---------------------------------------------+=
Courtesy of NationalSwitchgear.com