Maxim Integrated 78M6631 - Manual (Page 27)

UG_6631_078 78M6631 Firmware Description Document
Rev 2 27
3-Phase 4-Wire (Shunt)
An alternative to the previous configuration, the following figure shows a low-cost solution that is shunt-
based. As the previous configuration, the neutral is connected to V3P3 and is the reference potential for
both current and voltage measurements. The differential current inputs simplify the connections of the
shunt to the system .
A
Neutral
B
C
VC VB VA
LOAD A
LOAD B
LOAD C
IAP IAN IBP IBN ICP ICN V
3P
3A
A
Neutral
B
C
78M6631
Shunt A
Shunt B
Shunt C
D
/Y
Non-Isolated Basic Delta Connection
The system is referenced to a phase (in this case phase B). The currents are sensed at the phases A and
C, and the third current is calculated. Although this implementation allows only two CTs, it does not allow
the measurement of current of each load individually.
A
B
C
VC VB VA
LOAD A-C
IAP IAN IBP IBN ICP ICN V
3P
3A
A
B
C
78M6631
LOAD A-B
LOAD B-C
D
/Y