Application Guide - NP900 Series
36 (504
)
O
NLY LINE TO LINE VOLTAGES AVAILABLE
In case the line to line voltages are measured and zero sequence voltage is not measured
and known the three phase power calculation is based on Aaron’s theorem:
S = U
23
× I
L1
cos(30) + U
31
× I
L2
cos(30)
P = U
23
× I
L1
cos(30-
φ
) + U
31
× I
L2
cos(30 +
φ
)
Q = U
23
× I
L1
+ sin(30-
φ
) + U
31
× I
L2
sin(30 +
φ
)
Cosine and tangent phi is calculated similar way with line to neutral mode.
3.1.4.1
T
ROUBLESHOOTING
Check troubleshooting section in chapters “Current measurement and scaling” and
“Voltage measurement and scaling”. Faulty power and energy measurement is normally
related to same issues (wiring errors, wrong voltage measurement mode, faulty frequency
settings etc.).
3.1.4.2
S
ETTINGS
Table 3.1.4.2-31 Power and Energy meas. settings in NP900.
Name
Range
Step
Default
Description
EP meas 3ph
0:Disabled
1:Enabled
-
0:Disabled
Enable active energy measurement.
EQ meas 3ph
0:Disabled
1:Enabled
-
0:Disabled
Enable reactive energy measurement.
E 3ph M or k
0:Mega
1:Kilo
-
0:Mega
Measured energy in kilo –or mega values.
PQ Quadrant
VA Quadrant
Reset 3ph Energies
0:-
1:Reset
-
0:-
Resets the memory of each 3 phase
energy calculator. Goes back to “-“ -state
automatically after reset.
EP meas per phase
0:Disabled
1:Enabled
-
0:Disabled
Enable active energy per phase
measurement.
EQ meas per phase
0:Disabled
1:Enabled
-
0:Disabled
Enable reactive energy per phase
measurement.
E 3ph M or k
0:Mega
1:Kilo
-
0:Mega
Measured energy per phase in kilo –or
mega values.
Reset E per phase
0:-
1:Reset
-
0:-
Resets the memory of each phase energy
calculator. Goes back to “-“ -state
automatically after reset.
