Circutor Computer SMART III FAST 12, Instruction Manual

Page: 10 / 112

The safe use of the COMPUTER SMART III FAST requires the persons installing or handling it to follow
the general safety measures of LV electrical installations, as well as the warnings indicated in this in-
struction manual.
The unit will be installed on a panel (138+1 x 138+1 mm panel drill hole, in compliance with DIN 43700).
All connections are inside the electric panel.
Terminals, opening roofs or removing elements can expose parts that are hazardous to
the touch while the unit is powered. Do not use the unit until it is fully installed.
The unit must be connected to a power circuit that is protected with gl (IEC 269) or M type fuses with
a rating of 0.5 to 2 A. It must be fitted with a circuit breaker or equivalent device for disconnecting the
unit from the power supply mains.
The power and voltage measurement circuits as well as the relay contact circuits must be connected
with cables that have a minimum cross-section of 1.5 mm
2
.
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 unit of more than 25 m, this cross-section should be increased
by 1 mm
2
for every 10 m.
The current transformers (CT) must be installed at a point in the distribution panel which carries all the
current of the loads to be compensated as well as the current of the capacitors themselves (
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 unit 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
10
Computer SMART III FAST
Instruction Manual