5 - Operation
The unit operation is completely automatic.The below sequence explains (with the assistance of Fig. 5 - Opera tion diagram) how the unit operates (see also Fig. 6 Refrigerating circuit):
1)The temperature sensor, positioned inside the shel ter, informs the control about the condition of the air to be conditioned.
2)The control compares the received information with the Set Point values (= min. indoor temperature required) and Differential programmed values, pre setting the air conditioner for the air conditioning with the following modes:
Cooling (Fig. 5)
The compressor (9) and the fans (6) and (10) are started up when the temperature of the room to be conditioned exceeds the preset value. The intake air from the centrif ugal fan (6) enters the unit through the lower gap (A), goes immediately through the filter (1) and then the evaporator (5).
The cool refrigerant flows through the evaporator (5), thus cooling the air passing through it. The conditioned air is conveyed into the conditioned room through the discharge opening (B).
The heat taken from the room and the one generated by the conditioner motor operation are disposed through the condenser (11) placed in the lower part of the unit and hit, thanks to the fan (11), by the outside air. The fan operation is managed in ON - OFF mode (or with Variex, see par. 5.1) as a function of the condensing pres sure.
For the operation logics of the control see chapter 6.
Heating (optional)
The air heating is achieved by means of electric heaters (7), located in the air flow and activated according to the logics set on the control (see chapter 6).
The manual reset of the safety thermostat (15), placed on the electrical heaters is carried out throught the front after removing the grill panel.
Cooling in Freecooling (optional) - (Fig. 5)
When the outside air temperature is lower than the inside air temperature by some degrees, it is possible to use this difference to refresh the shelter inside part by direct intake of the outside air, i.e. without using the compressor. Thus it is possible to achieve a considerable energy saving.
When the expected conditions occur, the
(6)flows inside the container and is discharged through the openings of the condensing section. The air flows present in this operation mode are shown in Fig. 5).
The opening degree of the damper is determined as a function of the set point value to be kept and of the intake air temperature (see chapter 6).
5.1- Adjustment of the condenser fan speed (compulsory for outside temperatures
A sensor is positioned so as to detect constantly the con densing pressure of the refrigeration gas. On the basis of this information, an electronic device (Variex) adjusts the fan rotation speed in order to keep the condensing pressure within the allowed values. In this way, besides optimizing the compressor operation, you can have a remarkable reduction of the sound pressure level (mainly during the night), an easier
For the calibration of the speed adjuster refer to chapter 8.
5.2- Emergency cooling (optional)
This option is available for all those applications where it is mostly important to guarantee air flow inside the shel ter, even in the event of mains current drop. In this case, by an inverter and a transformer, the units can be sup plied by the emergency coils at 24 or 48 V dc (see Fig. 7). The intervention mode of the emergency system depends on the switch QS1 condition:
QS1 = ON
If the main power supply is not cut out, the emer gency system remains inactive;
if there is no voltage on the main power supply line, the inverter is automatically activated and, being sup plied by the emergency coils at 24/48 V dc, by the 24/48 V / 230 V transformer it supplies the fan of the evaporating section and the electronic control. So all functions of the unit are still managed, allowing the inside air to recirculate (or the outside air to come in, if the unit is provided with freecooling) if the temper ature inside the shelter is not within the permitted range. In this operation mode, a relay contact (KM6) signals the activation of the inverter system.
If the voltage of the emergency coils goes below the safety value, the inverter system is automatically de- activated.
QS1 = OFF
In this abnormal condition occurring, for instance, after a
CAUTION:
For safety reasons do disconnect the automatic switch QS2 when you want to stop the unit.
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