ABB A43 User Manual page 93

Measurement Methods
The following diagram shows a 3-element transformer connected meter with the
Illustration
neutral disconnected, that is left floating:
3-element metering with 2 transformers
It is also possible to use a 3-element meter with only 2 current transformers.
This type connection is possible both with and without the neutral available or
the neutral left floating.
Note that if the current transformers are connected to protective earth it must be
connected in only one point. Both methods require a balanced system (voltages
and currents the same in all 3 phases). It shall also be mentioned that having a
floating neutral also can give additional errors in the measured voltages due to
impedance unlinearity and imbalance inside the meter.
Illustration The following diagram shows a 3-element transformer connected meter with 2
current transformers:
2CMC48001M0201
Revision: C
L1
L2
L3
N
93
1 2 3 4 5 6 7
S1 S2
P1 P2
S1
P1
8 9 11
S2
P2
A43/A44
User Manual