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3 - HARDWARE DESCRIPTION
3.1 - General
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.
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 NRCP-
BASE board indicates correct operation. A different rate
indicates a board or a software failure.
•
On dual-circuit units or units equipped with optional
board, 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
SIO bus wiring problem.
•
On the master board, the orange LED flashes to show
when all communication is via the CCN bus.
3.4 - The sensors
Pressure sensors
Two types of electronic sensors (low and high pressure) are
used to measure the suction and discharge pressure in each
circuit.
Thermistors
The evaporator and condenser (option) water sensors are
installed in the entering and leaving side. An optional water
system temperature sensor can be used for master/slave
assembly control (in the case of leaving water control).
For certain options an outdoor temperature sensor or drycooler
water temperature sensor is available.
Legend
1
CCN connector
2
Red LED, status of the board
3
Green LED, communication bus SIO
4
Orange LED, communication bus CCN
5
Remote master board customer control connection contacts
6
Remote slave board customer control connection contacts
7
Master board customer connection relay outputs
8
Slave board customer connection relay outputs
9
Master NRCP basic board
10
Slave NRCP basic board
The control system consists of an NRCP-BASE board for
single-circuit units and two NRCP-BASE boards (a master and
a slave board) for dual-circuit units. Drycooler or remote air-
cooled condenser control is possible with an additional
PD-AUX1 board. All boards communicate via an internal SIO
bus. The NRCP-BASE boards continuously manage the
information received from the various pressure and temperature
probes. The NRCP-BASE master board 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 board and gives access to a full array of control
parameters.
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