Refrigerant Circuit; Refrigerating Circuit; Frame And Fans; Hydraulic Circuit - AERMEC NSB Serie Manual Tecnico

3. 1

REFRIGERANT CIRCUIT

Compressors
Semi hermetic high-efficiency screw
compressors, with a cooling capacity
regulation by means of continuous
modulation from 40 to 100% (from
25 to 100% with electronic valve) and
fitted with:
- Thermal motor protection
- Oil discharge temperature check
- Electrical heating element for the
heating of the oil casing with the
compressor at a standstill
- Reset button.
Water side heat exchanger
Shell & tube type exchanger of the
direct expansion type suitably scaled
to get high level performances.
Steel housing with closed cell foam
elastomer anticondensation mattress.
The pipe bundle is made with copper
tubes, with a special profile that allows
high heat exchange together with
efficient drainage. If so requested,
the exchanger can be fitted with an
anti-freeze electrical heating element,
(accessory only to be fitted in the
factory), that keeps the exchanger
from lower outside temperatures
down to -20°C, for the purpose of
avoiding the formation of ice in stand-by
mode. With the unit working protection
is provided by the outlet water
temperature probe.
Filter drier
With removable cartridge, it is able to
hold back the impurities and any traces
of humidity in the in cooling circuit.
Sight glass
For checking that the refrigerating
gas load and any humidity in the

refrigerating circuit.

Thermostatic valve
The mechanical type valve with outside
equaliser on the evaporator outlet
mdoulates the gas flow to the evaporator
dependent on the thermal load in such
a way as to ensure the proper intake
gas degree of overheating.
Liquid and pressing taps
They allow the refrigerant to be cut off
during extraordinary maintenance.
Silencer
Placed on the compressor delivery in
version E contributes to deaden sound
emission.
Solenoid valve
6
The valve closes when the compressor
turns off, preventing
of refrigerant gas towards
evaporator.
3.2

FRAME AND FANS

Fan unit
Screw type, statically and dynamically
balanced. The electric fans are protected
electrically with magnetothermal
switches and mechanically with anti-
intrusion metal grilles in accordance
with the CEI EN 294 60335-2-40
standard.
Load-bearing structure
Made of hot galvanised steel sheet of
an adequate thickness, it is painted
with polyester powders able to resist
the atmospheric agents over time.
Acoustic protection cover
Standard on all the NSB versions, it
consists of a compartment in very thick
steel sheet and insulated entirely with
soundproofing material. It permits the
acoustic power emitted by the unit to
be reduced and furthermore protects
the compressors from the atmospheric
agents.
3.3

HYDRAULIC CIRCUIT

Circulation pump
(only in versions with a pump)
This, depending on the characteristics
of the pump chosen, offers an effective
pressure to over come the pressure
drops in the system.
NOTE
When there is a second reserve pump,
switching is manual by operating the
selector switch inside the electrical
panel
Filling assembly
(only in versions with a pump)
This has a pressure gauge showing the
pressure in the system.
Expansion tanks
(only in versions with a pump)
3.4 SAFETY AND CHECKING
COMPONENTS
Differential pressure switch IP54
(installed as standard)
Its job is to make sure that there is
proper water circulation. If there is not,
it shuts down the unit
Low pressure transducer.
It makes it possible to show the value of
the compressor's intake pressure (one
the flow per circuit) on the microprocessor card
the display. Placed on the low pressure
side of the refrigeration circuit, it shuts
down compressor operation in the case
of abnormal operating pressure.
High pressure transducer
t makes it possible to show the value
of the compressor's delivery pressure
(one per circuit) on the microprocessor
card display. Placed on the high pressure
side of the refrigeration circuit, it shuts
down compressor operation in the case
of abnormal operating pressure.
Double high pressure switch (manual
+ tool)
With variable calibration, placed on the
high pressure side of the refrigeration
circuit, it shuts down compressor
operation in the case of abnormal
operating pressure.
Refrigeration circuit safety valves (HP, LP)
Calibrated to 22 bar HP - 16.5 LP, it cuts
in relieving the overpressure in the case
of abnormal operating pressures.
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/
CEE and 92/31/CEE. Furthermore,
all the cables are wired for immediate
recognition of all the electrical
components
Door lock sectioner
For safety the electrical panel can only
be accessed by cutting of the power
using the opening lever on the panel
itself. This lever can be locked in place
using one or more padlocks, during
maintenance in order to prevent
the machine being power ed up
accidentally.
Control keypad
Provides full control functions. For a
detailed description of the keypad refer
to the user manual.
- gate interlock system;
- 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 or fuses to be specified
when ordered.
- thermomagnetic fan protection;
- thermomagnetic auxiliary protection;
3.6 ELECTRONIC REGULATION