METREL MI 2893 - Page 183

MI 2893 / MI 2892 / MI 2885 Measurement methods
183
Combined phase active power:



N
j
j
p
j
p
N
j
j
pp
IU
N
p
N
P
11
11
[W], p: 1,2,3
(7)
Combined apparent and nonactive power, and power factor are calculated according to the following
equations:
Combined phase apparent power:
ppp
IUS 
[VA], p: 1,2,3
(8)
Combined phase nonactive power:
22
)(
pppp
PSQSignN 
[var], p: 1,2,3
(9)
Phase power factor:
p
p
p
S
P
PF 
, p: 1,2,3
(10)
Total combined power measurements
Standard compliance: IEEE STD 1459-2010
Total combined (fundamental + nonfundamental) active, nonactive and apparent power and total power
factor are calculated according to the following equation:
Total active power:
321 PPPPtot 
[W],
(11)
Total nonactive power:
321 NNNNtot 
[var],
(12)
Total apparent power (effective):
IeUeSetot  3
[VA],
(13)
Total power factor (effective):
tot
tot
tot
Se
P
PFe 
.
(14)
In this formula U
e
and I
e
are calculated differently for three phase four wire (4W) and three phase three
wire (3W) systems.
Effective voltage Ue and current Ie in 4W systems:
3
22
3
2
2
2
1 N
IIII
Ie


18
)(3
2
31
2
23
2
12
2
3
2
2
2
1
UUUUUU
Ue


(15)
Effective voltage U
e
and current I
e
in 3W systems:
3
2
3
2
2
2
1
III
Ie


9
2
31
2
23
2
12
UUU
Ue


(16)