ROOTECH Accura 3300, User Manual

Page: 40 / 46

Page 40
Reactive Power Calculation
Rootech supports two methods for accurate calculation of reactive power.
Method 1: General Calculation
Method 1 is used to obtain reactive power, and apparent power by using calculation of vector
apparent power.

=
T
a a a
dt t I t V
T
P
0
) ( ) (
1
,

=
T
b b b
dt t I t V
T
P
0
) ( ) (
1
,

=
T
c c c
dt t I t V
T
P
0
) ( ) (
1
c b a
P P P P
+ + =

+ =
T
a
T
a a
dt t I t V
T
Q
0
4
) ( ) (
1
,

+ =
T
b
T
b b
dt t I t V
T
Q
0
4
) ( ) (
1
,

+ =
T
c
T
c c
dt t I t V
T
Q
0
4
) ( ) (
1
c b a
Q Q Q Q
+ + =
2 2
Q P S
+ =
,
S
P
PF
=
2 2
a a a
Q P S
+ =
,
2 2
b b b
Q P S
+ =
,
2 2
c c c
Q P S
+ =
,
a
a
a
S
P
PF
=
,
b
b
b
S
P
PF
=
,
c
c
c
S
P
PF
=
Fig 2.2 P, Q[according to general calculation]
Note
When phase difference between voltage and current is within 90 degree of lead and lag, power
factor is positive. However, when phase difference is more than 90 degree[miswiring,
regeneration], power factor and active power are negative.