User's Manual

Appendices
Measuring Methods A
A-7
Symbols used in formulas:
P - is used for power Watt
S - is used for apparent power VA
Q - is used for reactive power var
Dh - is used for harmonics power
Du - is used for unbalance power
PF - Power Factor
DPF - Displacement Power Factor
P
1
- subscript 1 is used to indicate fundamental frequency components
P
1
+ - superscript + is used to indicate positive sequence components
∑ - (sigma) indicates summing of components. Sigma is also used to indicate that
classic method is used.
u - is used for voltage sample
i - is used for current samples
Tw - Time window of 10/12 cycles at 50/60 Hz
N - number of samples in 10/12 cycle periods
K - first sample of Tw record
n - sample number
U - is used for rms voltage calculated from samples over a 10/12 cycle window
I - is used for rms current calculated form samples over a 10/12 cycle window
X - is used to indicate phase A, B, C (or L1, L2, L3)
Υ - is used to indicate 4 wire wye configuration
Δ - is used to indicate 3 wire delta configuration