TEXA DEK Series, Installation, Operation And Maintenance Manual

Page: 7 / 32

thermostat and how to program it.
Pavarini Components shall be in no way held lia-
ble for any alterations the customer may make to
the default parameters if they have not received
authorisation to do so.
10. Maintenance
Warning! Caution! Before embarking on any
maintenance work, cut the current to the en-
closure.
The cooling unit is the low maintenance type, so
no filter change is required. The only maintenan -
ce required is for the internal components, which
should be checked regularly, as indicated in
the table given in this section, and cleaned with
compressed air at a maximum pressure of 4 bar
(figure F.11 ). Any repairs that may need doing
must only be performed by specialised and au-
thorised personnel.
11. Technical information
11.1 Operating principle
The cooling unit for electrical switchboard enclo-
sures works on the basis of a refrigeration circu-
it consisting of four main components: compres-
sor, evaporator, condenser and expansion devi-
ce (figure F.12 ). The circuit is hermetically sea-
led and the refrigerant circulates inside it. The
refrigerant used is R134a, chlorine free and har-
mless for the ozone layer. The unit is divided into
two hermetically separated sections where the
ambient air and enclosure air do not come into
contact with one another and are treated separa-
tely. The compressor (CP) compresses the refri-
gerant, taking it to a high pressure and high tem-
perature. The compressor then pushes the refri-
gerant through a heat-exchanger coil, called the
condenser (C), where it is cooled by ambient air,
thus passing from the gas to the liquid state. In
the liquid state it then passes through the expan-
sion valve (EXP), vaporising at the outlet as it is
now at a much lower pressure. It is then received
by the heat exchanger coil, called the evaporator
(E), by means of which it absorbs heat from the
enclosure air and passes from a liquid state to
gas. The enclosure is cooled down in this man-
ner. The gaseous refrigerant is then drawn back
into the compressor and this cycle is repeated.
11.2 Safety devices.
The refrigeration circuit is fitted with a high-pres -
sure safety switch P (figure F.12 ) set to the maxi-
mum working pressure of the cooling unit. If this
threshold is exceeded, the pressure switch stops
the compressor working. It resets automatically.
The fans and compressor have an (internal or
external) thermal cut-out switch that stops them
in the case of overheating. The emergency ru-
noff pipe permits the easy control of condensate
runoff operations. If runoff is through the emer-
gency pipe, this means the service runoff is blo-
cked and must therefore be cleaned.
11.3 Disposal
Caution! The cooling unit contains R134a re-
frigerant and small quantities of lubricating
oil. These are polluting substances and must not
be dumped. Replacement, repairs and final di -
sposal must be performed by experts.
NOTE
Keep the unit’s documentation in a safe, dry pla-
ce.
7
Remedy
This is not a malfunction of the cooling unit.
To verify functioning when testing, lower the thermostat setting until
the compressor and external fan start working and then reset the
thermostat.
Change the adjustment (or antifreeze) thermostat
This is not a malfunction of the cooling unit.
Make sure the power cable has been connected well to the
terminals.
Check that the cubicle doors and switches are closed
Call a refrigeration expert or the Manufacturer’s Technical Assist-
ance Service
Call a refrigeration expert or the Manufacturer’s Technical Assist-
ance Service
Change the internal fan’s capacitor
Change the internal fan
Change the amperometric protector
Change the relay or PTC for compressor starting
Change the capacitor for compressor starting
Call a refrigeration expert or the Manufacturer’s Technical Assist-
ance Service
Call a refrigeration expert or the Manufacturer’s Technical Assist-
ance Service
Change the contactor
Change the cooling unit with another of greater capacity
Clean the evaporator coil
See if there are any obstacles inside the enclosure to hinder the
flow of recycling air
Call a refrigeration expert or the Manufacturer’s Technical Assist-
ance Service
Check thermostat setpoint
Ventilate the premises where the enclosure is installed to keep
ambient temperature lower.
Clean the exchanger with compressed air and detergent
Ventilate the premises where the enclosure is installed to keep
ambient temperature lower.
Clean the coil with compressed air and detergent
This is not a malfunction of the cooling unit. Close the enclosure
door or disable the cooling unit
This is not a malfunction of the cooling unit. Seal enclosure open-
ings, e.g. for passage and upward path of wires
Check seal and remedy
Causes
The temperature inside the enclosure is lower than what
is set on the adjustment thermostat.
The adjustment (or antifreeze) thermostat has failed
No electricity getting to the unit.
Cooling unit empty of fluid
Compressor mechanical failure
Internal fan capacitor failed
Internal fan failed
Compressor’s amperometric protector failed (external to
the compressor, where present)
Relay or PTC for compressor starting failed
Capacitor for compressor starting failed (where present)
Compressor motor electrical failure
High pressure safety switch failed
Compressor contactor failed (where present)
Cooling unit under sized for the heat dissipated inside
the enclosure
Antifreeze thermostat triggered (where present)
Insufficient gas in the cooling unit
Thermostat set point incorrect
High pressure safety switch triggered:
Ambient temperature over the maximum work-
ing limit
Heat exchanger coil (condenser) either dirty or
clogged
Thermal protector inside the compressor triggered:
Ambient temperature over the maximum work-
ing limit
Heat exchanger coil (condenser) either dirty or
clogged
Too much ambient air inside the enclosure
Enclosure protection level is below IP54
The enclosure/cooling unit connecting seal has been
fitted incorrectly
Conditions
The internal fan works, the external fan and com-
pressor do not work.
No component works
Compressor, external and internal fan work
Compressor and external fan work, internal fan
does not work
External and internal fan work, compressor does
not work
External and internal fans work, compressor works
all the time
Inside fan works, external fan and compressor
work irregularly
External and internal fans work, compressor works
irregularly
Enclosure door open
Enclosure door closed
Malfunction
It fails to cool
It is not cooling enough
Too much condensate forming
•
•
•
•
•
•
•
•
12. Troubleshooting
•
•
•
•
Job
Check the external air
heat exchanger and
clean if necessary.
Check effectiveness
of the condensate
discharge.
Check the fans for any
overheating or exces-
sive vibrations.
Frequency
Every 3
months
Every 3
months
Every 6
months
ENG