4
Figure 1 - Control board
3.2 - Electrical supply to boards
All boards are supplied from a common 24 V a.c. supply
referred to earth.
In the event of a power supply interrupt, the unit restarts
automatically without the need for an external command.
However, any faults active when the supply is interrupted
are saved and may in certain cases prevent a circuit or unit
from restarting.
CAUTION: Maintain the correct polarity of the power
supply connection of the boards, to ensure that they are
not damaged.
3.3 - Light emitting diodes on boards
All boards continuously check and indicate the proper
operation of their electronic circuits. A light emitting diode
(LED) lights on each board when it is operating properly.
• The red LED that flashes for a two-second period - one
second on, one second off - indicates correct operation.
A different rate indicates a board or a software failure.
•
The green LED flashes continuously on all boards to
show that the board is communicating correctly over
its internal bus. If the LED is not flashing, this
indicates a LEN bus wiring problem.
•
The orange LED of the master board flashes during
any communication via the CCN bus.
3.4 - The sensors
Pressure sensors
Two types of electronic sensors are used:
•
low pressure: suction pressure and pump entering
pressure (optional),
•
high pressure: discharge pressure and economiser
pressure.
Thermistors
The heat exchanger water sensors are installed in the enter-
ing and leaving side. The outdoor temperature sensor is
mounted under a metal plate. An additional sensor placed
on an air heat exchanger pipe ensures defrost operation.
3.5 - The controls
Water circulation pump
The controller regulates the heat exchanger water pumps.
Heaters
They protect the heat exchanger (and the piping for units
without pump) against frost, if the unit has stopped and is
energised.
Boiler
This output authorises start/stop of a boiler.
3.6 - Connections at the user terminal block
3.6.1 - General description
The contacts below are available at the user terminal block
on the NRCP2-BASE boards. Some contacts can only be
used if the unit operates in remote operating type (Remote).
Contrast control
wheel
Back to the previous
screen
On/off key
- Unit stopped
- List of available operating
modes (only in local mode)
Green LED
Unit has stopped
Unit starts up
Unit in operation
Red LED
No alarm
Warning
Circuit or complete unit error
Up/Down key
- Navigation
- Modification
Enter key
- Validation
- Selection access
