Technical Information; Operating Principle; Safety Devices; Troubleshooting - pavarini EMO Serie Manual De Montaje Y Servicio

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.09). The circuit is hermetically sealed
and the refrigerant circulates inside it. The refrig-
erant used, depending on the cooling unit model,
is R134a, R407C or R410a, all chlorine free and
harmless to the ozone layer. The unit is divided
into two hermetically separated sections where
the ambient air and enclosure air do not come in-
to contact with one another and are treated sep-
arately. The compressor (CP) compresses the
refrigerant, taking it to a high pressure and high
temperature. The compressor then pushes the
refrigerant through a heat-exchanger coil, called
the condenser (C), where it is cooled by ambi-
ent air, thus passing from the gas to the liquid
state. In this state it then collects in the receiver
(R), from which it then passes through the ther-
mostatic expansion valve (EXP), where it vapor-

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
ises. It is then received by the heat exchang-
er 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 re-
frigerant 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 pressure switch Hp and a low-pressure
pressure switch Lp (figure F.09) set to the max-
imum and minimum working pressures, respec-
tively, of the cooling unit. If one of these thresh-
olds is exceeded, the pressure switch stops the
compressor's operation. They reset automatical-
ly. The fans and compressor have an (internal or
external) thermal cut-out switch that stops them
in the case of overheating.
11.3 Energy savings
To optimise energy savings, the cooling unit is
fitted with a pressure-switch speed regulator
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
(RLF) which adjusts the speed of the condens-
er fans based on the pressure in the refrigera-
tion circuit, which in turn depends on the ambi-
ent temperature.
11.4 Disposal
Caution! The cooling unit contains R134a,
R407 or R410A refrigerant, depending on the
model, as well as small quantities of lubri-
cating 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 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