HT Italia PQA819, User Manual

Page: 27 / 32

PQA819 - PQA820
EN – 26
12.3. DEFINITIONS OF POWER AND POWER FACTOR
In a generic electrical system, powered by a sequence of sinusoidal voltages, the following
is defined:
Phase Active Power:
(n=1,2,3)
) cos( I V P
n n nN n

  
Phase Apparent Power:
(n=1,2,3)
n nN n
I V S
 
Phase Reactive Power:
(n=1,2,3)
2 2
n n n
P S Q
 
Phase Power Factor:
(n=1,2,3)
n
n
n
F
S
P
P

Total Active Power:
3 2 1
P P P P
TOT
  
Total Reactive Power:
3 2 1
Q Q Q Q
TOT
  
Total Apparent Power:
2 2
TOT TOT TOT
Q P S
 
Total Power Factor:
TOT
TOT
TOT F
S
P
P

where:
V
nN
= Efficient value of voltage between phase n and neutral.
I
n
= Efficient value of the current of phase n.
f
n
= Phase angle between voltage and current of phase n.
With distorted voltages and currents, the above-reported ratios change as follows:
Phase Active Power:
(n=1,2,3)
) ( I V P
n
k
n
k
n
k
k
n

cos
0




Phase Apparent Power:
(n=1,2,3)
n nN n
I V S
 
Phase Reactive Power:
(n=1,2,3)
2 2
n n n
P S Q
 
Phase Power Factor:
(n=1,2,3)
n
n
n
F
S
P
P

Depurate Power Factor:
(n=1,2,3)
dPF
n
=cos f
1n
= phase angle between
the voltage and current
fundamentals of phase
n.
Total Active Power:
3 2 1
P P P P
TOT
  
Total Reactive Power:
3 2 1
Q Q Q Q
TOT
  
Total Apparent Power:
2 2
TOT TOT TOT
Q P S
 
Total Power Factor:
TOT
TOT
TOT F
S
P
P

where:
V
kn
= Efficient value of the k-nth voltage harmonic between phase n and neutral.
I
kn
= Efficient value of the k-nth current harmonic of phase n.
f
kn
= Phase angle between the k-nth voltage harmonic and the k-nth current harmonic of
phase n