Danfoss BW10 020-090, Operation Instructions Manual

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4
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 of the power supply
connection of the boards, to ensure that they are not
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 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
Refrigerant pressure sensors
Two types of electronic (high and low-pressure) sensors are
used to measure the suction and discharge pressure in each
circuit.
Water system pressure sensors
As an option, two electronic sensors are used to measure the
suction and the discharge pressure of the water pump. The
water flow rate is calculated, the unit is protected against water
flow losses and the pump is protected against cavitation (low
pump entering pressure).
Thermistors
The water temperature sensors are installed in the entering and
leaving side. Two optional water temperature sensors can be
used for master/slave assembly control (in the case of leaving
water control).
3.5 - The controls
Water circulation pumps
The controller can regulate each water heat exchanger pump and
takes care of automatic changeover between pumps. Variable-
flow pumps can control the heat exchanger temperature
difference or the water pressure difference.
Boiler
If there is a unit fault in the heating mode this output authorises
start-up and shutdown of a boiler.
Immersion heaters
The outputs of the AUX1 board permit control of the electric
resistance heaters. They are used as a supplementary heating
source in the heating mode.
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