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3 - HARDWARE DESCRIPTION
3.1 - General
Touch Pilot control interface
Touch Pilot control - view from below
Legend
1
Power supply connector (24 VAC)
2
LEN connector
3
CCN connector
4
Ethernet connector
5
USB connector
The control system consists of an NRCP2-BASE main board,
variators for compressor control, PD-AUX boards and an
NRCP2-BASE board for units equipped with energy manage-
ment option. All boards communicate via an internal LEN
bus. The ST3 touch control interface board continuously
manages the information received from the various pressure
and temperature probes, and incorporates the program that
controls the unit.
3.2 - Power supply to boards
All boards are supplied from a common 24 VAC. 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 two-second period on the
NRCP2-BASE 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.
When the unit is energised, all boards must flash in a
synchronised way. If a board does not flash at the same time
as the others, verify its connection at the LEN bus.
3.4 - The sensors
Pressure sensors
Two types of electronic sensors are used to measure the
following pressures in each circuit:
•
Discharge gas pressure (high pressure type)
•
Suction pressure (low pressure type)
•
Oil pressure (high pressure type)
These electronic sensors deliver 0 to 5 VDC. The pressure
sensors are connected to the AUX or NRCP2-BASE main
board.
Discharge pressure sensors
These are on the high pressure side of each circuit. They are
used to control head pressure or high pressure load shedding.
Oil pressure sensors
These sensors are located at the oil pressure port of each
compressor.
Suction pressure sensors
They measure the low-pressure side of each circuit.
Thermistors
These all have similar characteristics.
Evaporator entering and leaving water temperature sensor
The evaporator entering and leaving water temperature
sensors are installed in the entering and leaving side water box.
Discharge gas sensor
This sensor is used to control the discharge gas temperature,
and permits control of the discharge superheat. It is located
at the discharge side of each compressor.
Suction gas sensor
This sensor is used to control the suction gas temperature. It
is located at the suction side of each compressor.
Motor sensor
This is used to control the motor temperature of each
compressor.
