CCS WattNode Pulse WNB-3D-240-P, Справочное руководство

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Installation 13
Three-Phase Three-Wire Delta Without Neutral
This is typically seen in manufacturing and industrial environments. There is no neutral wire, just
three power lines with AC waveforms shifted 120° between the successive phases. With this
configuration, the line voltage wires may be connected to the
Ø A
,
Ø B
, and
Ø C
terminals in any
order, so long as the CTs are connected to matching phases . For these models, the meter is
powered from the
Ø A
and
Ø B
(phase A and phase B) terminals. Note: all delta WattNode models
provide a neutral connection
N
, which allows delta WattNode models to measure both wye and
delta configurations.
For best accuracy, we recommend connecting the
N
(neutral) terminal to earth ground. This will
not cause ground current to flow because the neutral terminal is not used to power the meter.
Ground
W
H
IT
E
B
L
AC
K
Ø B CT
Ø C CT
Ø A CT
Ø B
Ø C
N
Ø
A
Common
Input or Positive
Monitoring Equip-
ment or Display
P1
P2
P3
COM
O
u
tp
u
t
Status
Status
Status
W
ATT
N
ODE
®
P
ULSE
WNB -
WNB - - P
- P
Phase A
Phase B
Phase C
WHITE
BLACK
W
H
IT
E
B
L
AC
K
S
O
U
RC
E
LO
A
D
Source
Faces
Current
Transformers
3D - xxx
Figure 6: Three-Phase Three-Wire Delta Connection
Recommended WattNode Models
The following table shows the WattNode models that should be used, depending on the line-to-
line voltage (also called phase-to-phase voltage).
Line-to-Line Voltage WattNode Model
208 - 240 Vac WNB-3D-240-P
400 Vac WNB-3D-400-P
480 Vac WNB-3D-480-P
Three-Phase Four-Wire Delta (Wild Leg)
The uncommon four-wire delta electrical service is a three-phase delta service with a center-tap
on one of the transformer windings to create a neutral for single-phase loads.
See the website article Four Wire Delta Circuits for details.
Grounded Leg Service
In rare cases with delta services or single-phase two-wire services without neutral, one of the
phases may be grounded. You can check for this by using a multimeter (DMM) to measure the
voltage between each phase and ground. If you see a reading between 0 and 5 Vac, that leg is
probably grounded (sometimes called a “grounded delta”).