Safety And Control Components; Electrical Components - AERMEC NRA 0800 Manual Tecnico

the electronic card which enables the
alternate operation of the two pumps
to optimize the working time. A switch
on the NRA 1250 - 1400 - 1500 - 1650
- 1800 electric panel enables the pumps
to be manually switched over.
Flow switch only in versions with accumu-
lation feature and or pumps
This checks that the water is circulating. If
this is not the case, it shuts down the unit..
NOTE
In the versions without accumulation a flow
switch must be introduced or the WAR-
RANTY becomes void.
Water filter Supplied with standard ver-
sions (Mounted in versions with accumu-
lation and/or Pope)
Allows you to block and eliminate any
impurities in the hydraulic circuits. Inside, it
has a filtering mesh with holes not greater
than one millimetre. It is essential in order
to avoid serious damage to the plate heat
exchanger.
Accumulation tank
It is made of stainless steel, with a capacity
of 700 litres. In order to reduce the thermal
dispersion and eliminate the phenomenon of
the formation of condensation, it is insulated
with polyurethane material of a suitable
thickness. It is fitted, as standard, with an
anti-freeze heater (down to -20°C outside
temperature, tank water temperature
5°C), commanded by the anti-freeze probe
situated in the tank.
Drain valve
(only in the versions with hydronic unit or
pump(s))
Of the manual type, it discharges any air
pockets. It is intercepted by a stopcock so
that it can be substituted if necessary.
Filling unit
(only in the versions with accumulation or
pump(s))
This has a pressure gauge showing the
pressure in the system.
Two expansion tanks (of 25 litres)
(only in the versions with accumulation or
pump(s))
of the membrane type, with nitrogen pre-
charge.
Hydraulic circuit safety valve
(only in the versions with hydronic unit or
pump(s))
CALIBRATED AT 6 bar and with a discharge
that can be channelled, it intervenes by
discharging the overpressure in the event
of anomalous pressures.
6
3.4 SAFETY AND CONTROL
COMPONENTS
Low pressure switch
not present in the heat pump versions, as
these functions are carried out directly by
the board.
Of fixed calibration, located on the low
pressure side of the refrigerating circuit, it
stops the operation of the compressor in
the event of anomalous work pressures.
High pressure switch
Of variable calibration, located on the high
pressure side of the refrigerating circuit, it
stops the operation of the compressor in
the event of anomalous work pressures.
Anti-freeze heater
(installed as standard)
Its operation is commanded by the anti-
freeze probe located in the plate evaporator.
It is activated when the water temperature
is +3°C, and deactivated when the water
temperature is +5°C. The dedicated
software in the regulation card manages
the heater.
Refrigerating circuit safety valve
Calibrated at 30 Bar, it cuts in by letting off
the overpressure in the case of anomalous
pressures.
Low pressure transducers TP1,
standard in the heat pumps.
accessory in the cooling only versions
High pressure transducer TP2
standard on all the versions
3.5

ELECTRICAL COMPONENTS

Electrical panel
Contains the power section and the
management of the controls and safety
devices. This conforms with standard
CEI 60204-1, and Electromagnetic
Compatibility Directives EMC 89/336/
EEC and 92/31/EEC.
Door lock sectioner
IT IS POSSIBLE TO ACCESS THE ELECTRIC
PANEL BY disconnecting the voltage, then
using the opening lever of the panel itself.
This lever can be blocked with one or more
padlocks during maintenance, in order to
prevent the machine being powered up
accidentally.
Control keypad
Provides full control functions.
For a detailed description of the keypad
refer to the user manual.
Remote control panel
This allows the chiller command operations
to be given from a distance.
- t h e r m o m a g n e t i c c o m p r e s s o r
protection.
- thermomagnetic fan protection;
- thermomagnetic auxiliary protection.
- t her mos t a t f or dischar ge ga s
temperature control
3.6 ELECTRONIC REGULATION
Microprocessor card
Consisting of a management/control card and a
visualisation card. Functions carried out:
• regulation of evaporator water inlet
temperature (also outlet can be
selected), with thermostat action up
to 12 levels and proportional/integral
control of fan speed.
• delayed compressor start-up.
• operation as chiller, with possibility to
integrate refrigerating capacity by
means of "free-cooling".
• compressor sequence rotation.
• management of low temperature
device (accessory).
• compressor operation hour count.
• start/stop.
• reset.
• permanent alarms memory.
• automatic start-up after drop in
voltage.
• multi-lingual message service.
• operation with local or remote
control.
• visualisation of machine status:
ON/OFF compressors;
alarms summary.
• alarms management:
high pressure; flow switch;
low pressure; anti-freeze;
compressor overload;
fan overload; pump overload.
• v i s u a l i s a t i o n o f t h e f o l l o w i n g
parameters:
water inlet temperature;
evaporator water inlet temperature;
water outlet temperature; delta T;
high pressure; low pressure;
waiting time for restart.
• alarms visualisation.
• settings:
a) without password:
cooling set;
total differential;
b) with password:
anti-freeze set;
low pressure exclusion time;
display language;
access code.
For further information, refer to the user
manual.