Valhalla 2300 Operation Manual - page 105
106-5-1. 3-Phase 4-Wire VA's, VAR's
and PF
To determine VA's, VAR's and PF for 3-phase
4-wire connected loads, the following
procedure is recommended. Refer to Figure 1:
1) Connect the 2300 to the load as described
in Section 6.
2) Measure and record the voltage, current,
and power for each phase.
3) Calculate φA VA's and VAR's.
4) Calculate φB VA's and VAR's.
5) Calculate φC VA's and VAR's.
6) Add φA, φB and φC VAR's to obtain 3-
phase VAR's.
7) Add φA, φB and φC watts to obtain 3-
phase watts.
8) Calculate 3-phase VA's from 3-phase
VAR's and watts.
9) Calculate 3-phase PF from 3-phase VA's
and watts.
When calculating 3-phase VAR's, it is safe to
assume that the individual phase power
factors are all lagging if the load has a
transformer or motor. An oscilloscope or
Valhalla Model 2110A/2111A may be used if
there is any doubt.
106-5-2. 3-Phase 3-Wire VA's, VAR's
and PF
To determine VA's, VAR's and PF in 3-phase
3-wire connected loads the following
procedure is recommended. Refer to Figure
1.
1) Connect the 2300 to the load as described
in Section 6.
2) Measure and record the voltage, current
and power for φA and φC.
3) Calculate φA VA's and VAR's.
4) Calculate φC VA's and VAR's.
5) Add φA and φC VAR's to obtain 3-phase
VAR's.
6) Add φA and φC watts to obtain 3-phase
watts.
7) Calculate 3-phase VA's from 3-phase
VAR's and watts.
8) Calculate 3-phase PF from 3-phase VA's
and watts.
When calculating 3-phase VAR's it is safe to
assume that the individual phase power
factors are all lagging if the load has a
transformer or motor. An oscilloscope or
Valhalla Model 2110A/2111A may be used if
there is any doubt.
106-6. PF and VAR Accuracies
The accuracies of the PF and VAR
calculations are the sums of the accuracies of
the voltage, current and power measurements.
For the 2300, the accuracies are as shown
below:
SINGLE PHASE
± (0.1% V rdg + 0.1% V rng)
± (0.25% A rdg + 0.25% A rng)
± (0.25% W rdg + 0.25% W rng)
3-PHASE 3-WIRE
± (0.1% V
a
rdg + 0.1% V
c
rdg + 0.2% V rng)
± (0.25% A
a
rdg + 0.25% A
c
rdg + 0.5% A rng)
± (0.25% W
a
rdg + 0.25% W
c
rdg + 0.5% W rng)
3-PHASE 4-WIRE
± (0.1% V
a
rdg + 0.1% V
b
rdg + 0.1% V
c
rdg + 0.3% V
rng)
± (0.25% A
a
rdg + 0.25% A
b
rdg + 0.25% A
c
rdg+ 0.75%
A rng)
± (0.25% W
a
rdg + 0.25% W
b
rdg + 0.25% W
c
rdg +
0.75% W rng)