Maintenance; Technical Information; Operating Principle; Safety Devices - ORELL EMO Serie Manual De Montaje Y Servicio

10. Maintenance

Warning! Caution! Before embarking on any
maintenance work, cut the current to the
enclosure.
Job Frequency
Check the external air Every 3
heat exchanger and months
clean if necessary.
Check effectiveness
Every 3
of the condensate
months
discharge.
Check the fans for any
Every 6
overheating or exces-
months
sive vibrations.
The cooling unit is the low maintenance type, so
no filter change is required. The only maintenance
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 autho-
rised personnel.

12. Troubleshooting

Malfunction Conditions
It fails to cool The internal fan works, the external fan and
compressor 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

11. Technical information

11.1 Operating principle

The cooling unit for electrical switchboard enclo-
sures works on the basis of a refrigeration circuit
consisting of four main components:
compressor, evaporator, condenser and expansion
device (figure F.12). The circuit is hermetically
sealed and the refrigerant circulates inside it. The
refrigerant used is R134a, chlorine free and harm-
less 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 refrige-
rant, taking it to a high pressure and high tempera-
ture. The compressor then pushes the refrigerant
through a heat-exchanger coil, called the conden-
ser (C), where it is cooled by ambient air, thus pas-
sing from the gas to the liquid state.
In the liquid state it then passes through the
expansion 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 manner. The gaseous refrigerant is then
drawn back into the compressor and this cycle is
repeated.
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
working limit
• Heat exchanger coil (condenser) either dirty or
clogged
Thermal protector inside the compressor triggered:
•
Ambient temperature over the maximum
working 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
6

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
threshold 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
pressure decreases below the fixed threshold.
Also the low pressure safety switch is automati-
cally 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.

11.3 Disposal

Caution! The cooling unit contains R134a refri-
gerant and small quantities of lubricating oil.
These are polluting substances and must not be
dumped. Replacement, repairs and final disposal
must be performed by experts.
NOTE
Keep the unit's documentation in a safe, dry place.
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 Assis-
tance Service
Call a refrigeration expert or the Manufacturer's Technical Assis-
tance 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 Assis-
tance Service
Call a refrigeration expert or the Manufacturer's Technical Assis-
tance 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 Assis-
tance 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
openings, e.g. for passage and upward path of wires
Check seal and remedy
ENG