Alstom iSTAT M232 - Appendix B: Calculations & Equations; Definitions of Symbols

User Manual M2x2/EN M/F
iSTAT M2x2 Page 66
18. APPENDIX B: CALCULATIONS & EQUATIONS
18.1 Definitions of symbols
No Symbol Definition
1 M
v
Sample factor
2 M
P
Average interval
3 U
f
Phase voltage (U
1
, U
2
or U
3
)
4 U
ff
Phase-to-phase voltage (U
12
, U
23
or U
31
)
5 N Total number of samples in a period
6 n Sample number (0 ≤ n ≤ N)
7 x, y Phase number (1, 2 or 3)
8 i
n
Current sample n
9 u
fn
Phase voltage sample n
10 u
fFn
Phase-to-phase voltage sample n
11 φ
f
Power angle between current and phase voltage f (φ
1
, φ
2
or
φ
3
)
18.2 Equations
Voltage
N
u
=
U
2
n
N
1=n
f

Phase voltage
N − 128 samples in one period (up to 65 Hz)
N − 128 samples in M
v
periods (above 65Hz)
Example: 400 Hz → N = 7

N
2
ynxn
N
1=n
xy
uu
=
U


Phase-to-phase voltage
u
x
, u
y
− phase voltages (U
f
)
N − a number of samples in a period
Current
N
=
i
I
2
n
N
1=n
RMS

Phase current
N − 128 samples in a period (up to 65 Hz)
N − 128 samples in more periods (above 65
Hz)