Nibe S1255-12, Installer Manual, Page: 22 / 92

S1255 External
BE6
+O
T
+O
T
0
-5
V
+5
V
G
N
D
9 5 6 7 8
AA2-X30
+5V
+5V
0
-5
V
+5
V
AU
X
1
AU
X
2
AU
X
3
AA2-X28
5 1 2 3 4
BE7
Activate the energy meter(s) in menu 7.2 and then set
the desired value (energy per pulse) in menu 7.2.19.
Load monitor
Integrated load monitor
S1255 is equipped with a simple form of integrated load
monitor, which limits the power steps for the electric
additional heat by calculating whether future power
steps can be connected to the relevant phase without
exceeding the specified main fuse. If the current would
exceed the specified main fuse, the power step is not
permitted. The size of the property’s main fuse is spe-
cified in menu 7.1.9.
Load monitor with current sensor
When many power-consuming products are connected
in the property at the same time as the electric additional
heat is operating, there is a risk of the property’s main
fuses tripping. S1255 is equipped with a load monitor
which, with the aid of a current sensor, controls the
power steps for the electric additional heat by redistrib-
uting the power between the different phases or by
disengaging the electric additional heat in event of an
overload in a phase. If the overload remains despite the
electric additional heat being disengaged, the com-
pressor winds down. Reconnection occurs when the
other current consumption drops.
Caution
Activate phase detection in menu 7.1.9 for full
functionality.
Connecting current sensors
A current sensor should be installed on each incoming
phase conductor in to the distribution box to measure
the current. The distribution box is an appropriate install-
ation point.
Connect the current sensors to a multi-core cable in an
enclosure directly adjacent to the electrical distribution
unit. The multi-core cable between the enclosure and
S1255 must have a cable area of at least 0.5 mm².
L PEN
1
L
2
L
3
Electrical
distribution unit
NIBE product
Incoming electricity
Connect the cable to terminal block AA2-X30:9-12,
where X30:9 is the common terminal block for the three
current sensors.
+5
V
BE1 BE2 BE3
BE1 BE2 BE3
11 10
9 8
12
G
N
D
AA2-X30
COMMUNICATION
Multi-installation
Several heat pumps can be interconnected by selecting
one heat pump as the main unit and the others as sub-
ordinate heat pumps. Ground source heat pump models
with multi-installation functionality from NIBE can be
connected to S1255.
A further eight heat pumps can be connected to the
main unit. In systems with several heat pumps, each
pump must have a unique name. Only one heat pump
can be "Main unit" and only one can be e.g. "Heat pump
5". Main unit/heat pump are set in menu 7.3.1.
External temperature sensors and control signals must
only be connected to the main unit, except for external
control of the compressor module.
NOTE
When several heat pumps are connected to-
gether, an external supply temperature sensor
(BT25) and an external return line sensor (BT71)
must be used.
Connect the communication cables between the heat
pumps as illustrated in series to terminal block X30:1
(GND), X30:2 (+12V), X30:3 (B) and X30:4 (A) on the
PCB (AA2).
Use cable type LiYY, EKKX or similar.
The example shows the connection of several S1255 .
NIBE S1255 Chapter 5 | Electrical connections 22