Connect Current Transformers; Ct Wiring - Fronius Smart Meter 240V-3 UL Operating Instructions Manual

Three-Phase Two-Wire Corner Grounded Delta (only 240V-3 and 480V-3)
Connect Current The current transformer must generate 333.33 millivolts AC at rated current. See the cur-
Transformers rent transformer data sheets for CT ratings.
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Install the CTs around the conductor to be measured and connect the CT leads to the Fro-
nius Smart Meter. Always turn off power before disconnecting any live conductors. Put the
line conductors through the CTs as shown in the previous section.
CTs are directional. If they are mounted backwards or with their white and black wires
swapped the measured power will be negative. The status LEDs indicate negative mea-
sured power by flashing red.
Split-core CTs can be opened for installation around the conductor. A nylon cable tie may
be secured around the CT to prevent inadvertent opening.

CT Wiring

The current transformers connect to the six position black screw terminal block. Connect
the white and black CT wires to the Fronius Smart Meter terminals marked CT L1, CT L2
and CT L3. Excess length may be trimmed from the wires if desired. Connect each CT with
the white wire aligned with the white dot on the label and the black wire aligned with the
black dot. Note the order in which the phases are connected, as the line voltage phases
must match the current phases for accurate power measurement.
14
Fronius
D- D-
Datama-
D+ D+
nager
- -
CT L1
Shorting
CT L2
Jumper
CT L3
Source
Faces
Load
Faces
Current
Transformers
Do not use ratio or current output such as 1 amp or 5 amp output models!
See the CT data sheets for the maximum input current ratings.
Be careful to match the CTs with the voltage phases. Make sure the CT L1 is measur-
ing the current on the same phase being monitored by the L1 voltage input and the
same for phases L2 and L3. Use the supplied colored labels or colored tape to identify
the CT leads.
To minimize current measurement noise, avoid extending the CT wires, especially in
noisy environments. If it is necessary to extend the wires, use twisted pair cable 22 to
14 AWG, rated for 300 V or 600 V (not less than the service voltage) and shielded if
possible
Make sure the CTs face the correct direction. An arrow might indicate either the load
or the source (public grid)
If you see strange readings on unused phases, jumper the unused CT inputs: for each
unused CT, connect a short cable from the terminal marked with a white dot to the ter-
minal marked with a black dot.
Fronius Smart Meter
N
L1
L2
L3
Fuses or
Breaker ≤ 20 A
Phase L1
Phase L2
(Ground)
Phase L3