Amprobe DM-4 Power-Quality-Recorder - Manual (Page 55)

15.3.2 3 Phase 3 Wire System
In the electrical systems distributed without neutral, the phase voltages and the
power factors and phase cosj lose importance. Only the phase to phase voltages,
the phase currents and the total powers remain defined.
Phase 1
Phase 2
Phase 3
In this case the potential of one of the three phases (for example, phase 2) is taken
on as reference potential. The total values of the active, reactive and apparent
power are expressed as sum of the indications of the couples of Wattmeters,
VARmeters and VAmeters.
54
DM-4 Power Quality Recorder
Value Significance
P The active power (positive or negative) is defined in the panel and therefore acquires the
value of the active power in that moment.
Q The reactive power (inductive or capacitive, positive or negative) is defined in the panel and
therefore acquires the value of the reactive power in that moment.
Pf The power factor (inductive or capacitive, positive or negative) is defined in the panel and
therefore acquires the value of the power factor in that moment.
0 The active power (positive or negative) or the reactive power (inductive or capacitive,
positive or negative) is NOT defined in the panel and therefore acquires a null value.
-1 The power factor (inductive or capacitive, positive or negative) is NOT defined in the panel.
Three-phase
equipment
W 1-2
W 3-2
VAR1-2
VAR3-2
P
TOT
= W
1-2
+ W
3-2
Q
TOT
= VAR
1-2
+ VAR
3-2
S
TOT
= (W
1-2
+ W
3-2
) 2 + (VAR
1-2
+ VAR
3-2
) 2
√