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5.3
Refrigerant charge verification
The multiporpouse units are design to operate in extremely variable conditions and modes (air to water ans water to water).
The refirgerant charge indicated on the name plate has been approved by the manufacturer allowing the unit to operate
within the declared operating envelope. The highgly variable conditions lead to situations where the sight glass on the
liquid line shows flashing of the refrigerant. Generally this phenomenon lead the field operator to charge refrigenat in the
unit. On a mutlipurpose unit doesn
’t add or remove refrigerant based only on the indication of the flashing in sight glass.
The refrigerant charge must be adjusted in water to water operation (Recovery mode) in order to avoid flashing at sight
glass on the liquid line
5.4
Inverter Electrolytic Capacitors
Compressor Inverters include electrolytic capacitors which have been designed to last a minimum of 15 years in normal
use. Heavy duty conditions may reduce the actual life of capacitors.
The unit calculates capacitor residual life based on actual operation. When residual life gets below a give threshold, a
warning is issued by the controller. In this case replacement of capacitors is recommended. This operation must be done
only by qualified technicians. Replacement must be carried out through the following procedure:
•
Power off the unit
•
Wait for 5 minutes before opening the inverter case
•
Check that residual dc voltage in the dc link is zero.
•
Open the inverter case and replace old capacitors with new ones.
•
Reset the unit controller through the maintenance menu. This will allow the controller to recalculate the new
estimated life of the capacitors.
Capacitor Reforming after long shut-off period
Electrolytic capacitors may lose part of their original characteristics if they are not powered for more than 1 year. If unit has
been shut off for a longer period a “reforming” procedure as follows is necessary:
•
Power on the inverter
•
Keep it powered on without starting the compressor for at least 30 minutes
•
After 30 minutes the compressor can be started
Low Ambient Start-up
Inverters include a temperature control which allows them to withstand ambient temperatures down to -20°C. However
they should not be switched on at temperatures lower than 0°C unless the following procedure is executed:
•
Open the switchbox (only trained technicians should perform this operation)
•
Open compressor fuses (by pulling the fuse holders) or compressor circuit breakers
•
Power on the unit
•
Keep the unit powered on for 1 hour at least (this allows inverter heaters to warm-up the inverter).
•
Close fuse holders
•
Close the switchbox
