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3 - DESCRIPCION DEL HARDWARE
3.1 - GENERALIDADES
The control system consists of a PD5-BASE board, SPM
boards for compressor control, PD-AUX boards for fan
control, and an NRCP2-BASE board for units equipped
with energy management option or heat reclaim option.
All boards communicate via an internal LEN bus. The
PD5-BASE boards continuously manage the information
received from the various pressure and temperature
probes, and incorporates the program that controls the
unit.
The user interface consists of two display blocks with up
to 26 LEDs and 16 buttons (according to unit type). It is
connected to the main basic board and gives access to
a full array of control parameters.
3.2 - ELECTRICAL SUPPLY TO BOARDS
All boards are supplied from a common 24 V a.c. supply
referred to earth.
CAUTION:
Maintain the correct polarity when connecting
the power supply to the boards, otherwise the boards may
be damaged.
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.
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 flashing for a 2 second period on the
NRCPBASE board 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 to measure the
suction and discharge pressure in each circuit.
Thermistors
The evaporator water sensors are installed in the entering
and leaving side. The outdoor temperature sensor is
mounted below the control box. An optional water system
temperature sensor can be used for master/slave
assembly control (in the case of leaving water control).
In heat pump units a sensor placed on an air heat
exchanger pipe ensures defrost operation.
3.5 - THE CONTROLS
Evaporator pumps
The controller can regulate one or two evaporator pumps
and takes care of automatic change-over between
pumps.
Evaporator heater
It protects the evaporator (and the pipe heater for units
without pump) against freezing if the unit is off.
Boiler
This relay output authorises start/stop of a boiler.
3.6 - CONNECTIONS AT THE USER'S TERMI-
NAL BLOCK
3.6.1 - GENERAL DESCRIPTION
The contacts below are available at the user's terminal
block on the PD5-BASE board (see figure 1). Some of
them can only be used if the unit operates in remote
operating type (rEM). The following table summarises
the connections at the user’s terminal block.
Legend
1 : CCN connector
2 : Red LED, status of the board
3 : Green LED, communication bus LEN
4 : Orange LED, communication bus CCN
5 : PD5 basic board
6 : Remote customer control connection contacts
7 : Master board customer connection relay outputs
1
4
2 3
5
7
6
