Technical Information; Operating Principle; Safety Devices; Disposal - pavarini EMO series Anleitung

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

12. Troubleshooting

Malfunction Conditions
It fails to cool 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
It is not cooling enough 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
Too much condensate forming Enclosure door open
Enclosure door closed
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 HP (figure F.12) set at maxi-
mum cooling unit working pressure. If the thresh-
old is exceeded, the pressure switch stops the
com pressor working. It is the auto matically re-
settable type. The low pressure safety switch LP
stops the compressor when the suction pres-
sure decreases below the fixed threshold. Also
the low pressure safety switch is automatically
resettable. The fans and com pressor feature a
thermal cut-out switch (both inside and outside)
that stops them in the case of anomalous over
temperatures. A condensation control pressure
switch (FSD) is mounted on the condenser fan;
it controls the condenser fan speed to keep the
condensing temperature constant.
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
7

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.
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
ENG