Alstom iSTAT M355, Manual

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M3x5/EN M/B User Manual
Page 86
iSTAT M3x5

Signalling phase and phase-to-phase voltages (Us1-3, Us12, Us13, Us23)

DC component of phase and phase-to-phase voltages including neutral line
N
u
=
U
2
n
N
1 = n
f

 
N
2
yn xn
N
1 = n
xy
u u
=
U


All voltage measurements are available on communications and on standard or customized
displays on the LCD.
The device warns if the input signal is too large. Indicator is shown above the
parameter unit:
«
(KD) Main menu  Measurements  Present values  Voltage
12.4.1.2 Current
The device measures:

Real effective (rms) value of phase currents and neutral measured current (Inm),
connected to current inputs

Neutral calculated current (Inc), Neutral error current (Ie = |Inm – Inc|),

Phase angle between Neutral voltage and Neutral Current (

In), Average current (Ia) and
a sum of all phase currents (It)

Crest factor of phase currents (CRI1-3)
N
i
=
2
n
I
N
1 = n
RMS

All current measurements are available on communications and on standard and customized
displays on the LCD.
(KD) Main menu  Measurements  Present values  Current
12.4.1.3 Active, Reactive and Apparent Power
Active power is calculated from the instantaneous phase voltages and currents. All
measurements are available on communications or are displayed on LCD. For more
detailed information about calculation see Appendix D.
There are two different methods of calculating reactive power, see Appendix D.
The device warns if the input signal is too large. Indicator is shown above parameter
unit:
«