Circutor Computer SMART III 12, Instruction Manual

Page: 11 / 114

One or three external current transformers (CT) need to be installed in order to measure current. Usu-
ally, the transformation ratio of these CTs is In/5 A, where In is at least 1.5 times the total maximum
load current.
The secondary cables of the current transformers (CT) must have a minimum cross-section of 2.5
mm
2
. For distances between the CTs and the device of more than 25 m, this cross-section should be
increased by 1 mm
2
for every 10 m.
The current transformers (CTs) must be installed at the power line connection point which carries all
the current of the loads to be compensated as well as the current that is specific to the capacitors
(
Figure 1
).
CORRECT INCORRECT
~
P1
P2
S1
S2
TC
LOAD CAPACITORS
The current transformers (CT) must
measure the combined current of the
capacitors plus the loads
If it does not work, make sure that the
CTs are not short-circuited.
~
LOAD
CAPACITORS
P1
P2
S1
S2
TC
If the CTs are connected in this
position, NONE OF THE CAPACITORS
WILL BE CONNECTED, even if there
are inductive loads.
The device does not compensate�
~
LOAD
CAPACITORS
P1
P2
S1
S2
TC
If the CTs are connected in this
position ALL THE CAPACITORS WILL
BE CONNECTED, but they will not be
disconnected if the load drops.
Risk of over-compensation in the
grid with no load�
Figure 1: Location of the current transformers
11
Instruction Manual
Computer SMART III