Alstom iSTAT M355, Руководство пользователя

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M3x5/EN M/B User Manual
Page 146
iSTAT M3x5
22. APPENDIX D: EQUATIONS
Definitions of symbols
No Symbol Definition
1 M
P
Average interval
2 U
f
Phase voltage (U
1
, U
2
or U
3
)
3 U
ff
Phase-to-phase voltage (U
12
, U
23
or U
31
)
4 N Total number of samples in a period
5 n Sample number (0 ≤ n ≤ N)
6 x, y Phase number (1, 2 or 3)
7 i
n
Current sample n
8 u
fn
Phase voltage sample n
9 u
fFn
Phase-to-phase voltage sample n
10 φ
f
Power angle between current and phase voltage f ( φ
1
, φ
2
or φ
3
)
11 U
u
Voltage unbalance
12 U
c
Agreed supply voltage
Voltage
N
u
=
U
2
n
N
1 = n
f

Phase voltage
N − samples in averaging interval
(up to 65 Hz)
 
N
2
yn xn
N
1 = n
xy
u u
=
U


Phase-to-phase voltage
u
x
, u
y
− phase voltages (U
f
)
N − a number of samples in averaging interval
 
2
2
fund 31
2
fund 23
2
fund 12
4
fund 31
4
fund 23
4
fund 12
u
U U U
U U U
% 100
6 3 1
6 3 1
U
 
 
 

  
  

Voltage unbalance
U
fund
− first harmonic of phase-to-phase voltage
Current
N
=
i
I
2
n
N
1 = n
RMS

Phase current
N − samples in averaging interval
(up to 65 Hz)
 
N
i i i
=
2
n 3 n 2 n 1
N
1 = n
n
I
 

Neutral current
i − n sample of phase current (1, 2 or 3)
N − samples in averaging interval
(up to 65 Hz)