Hardware Description; General; Electrical Supply To Boards; Light Emitting Diodes On Boards - Carrier 30RQ Operation And Maintenance Instructions

3 - HARDWARE DESCRIPTION

3.1 - General

Figure 1 - control board
1
5
7
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
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.
4
2 3
1 4
6

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.
• 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 tempera-
ture 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.