Electrical Power Systems

Case-1:
If P 1 = P 2 = P 3 = ... = P n = P
Then
C =
n
å i
i=1
P ´ C
P ´ n
Structure of Power Systems and ew Other Aspects 7
That is, the coincident factor is equal to the average contribution factor.
Case-2:
If C 1 = C 2 = C 3 = ... = C n = C,
Then
C =
C ´ å Pi
=
n
å
i=1
n
C
i
...(1.17)
n = C ...(1.18)
P
å
i=1
n
i=1
i
That is, coincidence factor is equal to the contribution factor.
Load actor: It is the ratio of the average load over a designated period of time to the peak
load occurring on that period.
Therefore, the load factor (L) is defined as:
or
L =
L =
Average load
Peak load
Average load ´ T
Peak load ´ T
... (1.19)
Energy served
\ L = ...(1.20)
Peak load ´ T
where T = time, in days, weeks, months or years. If T is large, L is small. The reason for this
is that for the same maximum demand, the energy consumption covers a larger time period and
results in a smaller average load. Load factor is less than or equal to unity. Annual load factor
is defined as:
Annual Load actor =
Total annual energy
Annual peak load ´ 8760
...(1.21)
Loss actor: It is the ratio of the average power loss to the peak-load power loss during a
specified period of time. Therefore, the loss factor (LL) is defined as:
LL =
Average power loss
Power loss at peak load
...(1.22)
Equation (1.22) is applicable for the copper losses of the system but not for iron losses.