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6
Starting Up
6.1
Preliminary checks
•
Check that the electrical connections have been made properly and that all the terminals are securely
tightened. This check should also be included in a periodic six-month inspection.
•
Check that the voltage at the RST terminals is 400 V ± 5%and make sure the yellow indicator light of the
phase sequence relay is on. The phase sequence relay is positioned on the electric control board; if the
sequence is not duly observed, it will not enable the machine to start.
•
Make sure there are no refrigerant leaks that may have been caused by accidental impacts during
transport and/or installation.
•
Check the power supply to the crankcase heating elements, where present.
The heating elements must be turned on at least 12 hours before the unit is started. They
are automatically activated when the main switch is put on. Their function is to raise the T of
the oil in the sump and limit the quantity of refrigerant dissolved in it.
To verify whether the heating elements are working properly, check the lower part of the compressors: it
should be warm or in any case at a temperature 10---15 °C higher than the ambient temperature.
Fig. 6
Diagramma legge di Charles
The diagram in Fig. 6 illustrates a specific property of gases (Charles' Law), which are more soluble in liquids
as the pressure increases but less soluble as the temperature increases: if the oil in the sump is held at a
constant pressure, an increase in temperature will significantly reduce the amount of refrigerant dissolved in
it, thus ensuring that the desired lubricating function is maintained.
@DNOVA THN_R410A-IOM-1506-E
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