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4. Controller functions
The cooling unit is used where heat needs to be dissipated from electrical control cabinets or similar enclosures
in order to protect heat sensitive components. The unit has two completely separate air circuits which ensure
that the clean cabinet air does not come into contact with the ambient air which may well be dirty or polluted. It
is not intended for household use. Control cabinet air conditioners can dissipate large quantities of heat from
sealed enclosures such as control cabinets into the ambient air and at the same time reduce the cabinet
internal temperature to below that of the ambient air.
The control cabinet air conditioner can function without problems in extreme ambient conditions (e.g. dusty and
oily air) with an standard operating temperature ranging between 50°F and 131°F. The stated cooling capacities
are according to DIN 3168.
Controller
The unit is equipped with a temperature controller which regulates the function of the air-conditioning cycle. At
normal working conditions the display shows the temperature inside the enclosure. The cooling set point for the
interior of the enclosure (parameter St / St1) is pre-set at 95°F and can be adjusted between 68°F and 122°F.
To change the cooling set point St/St1:
1. Press ‘Set’ till St/St1 appears on the display.
2. Press the Up/Down buttons to adjust the temperature setting.
3. Press ‘Set’ to save the new setting.
To change the heating set point St2 (Units with internal heater only):
1. Press ‘Set’ till St1 appears on the display and release the button.
2. Press again ‘Set’ till St2 appears on the display.
3. Press the Up/Down buttons to adjust the temperature.
4. Press set to save the new setting.
Important Note: when changing settings ensure that: (St2 + 5K) < St1
The unit also has a potential free high temperature alarm relay (normally closed configuration) that is pre-set to
switch when the enclosure temperature exceeds 131°F. If necessary the alarm relay configuration and the set
point can be changed via the controller’s parameters. Kindly contact your nearest service / sales partner for
further details on how to change these parameters.
5. Functional principle
The cooling unit for enclosures works on the basis of a refrigeration circuit consisting of four main
components: compressor (1), evaporator (2), condenser (3) and expansion device (4).
The circuit is hermetically sealed and R134a refrigerant circulates inside it (R134a is chlorine free and has an
Ozone Destruction Potential [ODP] of 0 and a Global Warning Potential [GWP] of 1430). The compressor
compresses the refrigerant (thus taking it to high pressure and high temperature), and pushes it through the
condenser, where it is cooled by ambient air thus passing from the gas to the liquid state. At the liquid state it
then passes through the capillary pipe being a much lower pressure the refrigerant arrived to the evaporator
where it absorbs the necessary heat to change from liquid to gas state. The gas is then drawn back into the
compressor completing the cycle.
Condensation management
In environments with humidity and low internal enclosure temperatures, condensation may form on the
evaporator coil. Standard cooling units 43XXX0XXX have a drain socket towards the bottom of the unit for
connection of the drain pipe.
Cooling units 43XXX2XX include an internal condensate evaporator based on self-regulating PTC cartridges.