Electrical Maintenance - Carrier AQUASNAP 30RA B Series Manual

12.2.2 - Principles
Refrigeration installations must be inspected and maintained
regularly and rigorously by specialists. Their activities must be
overseen and checked by properly trained people. To minimise
discharge to the atmosphere, refrigerants and lubricating oil
must be transferred using methods which reduce leaks and
losses to a minimum and with materials that are suitable for the
products.
• Leaks must be repaired immediately
• All units are equipped with two special connections on the
suction and liquid line, which permit the connection of
quick-connect recovery valves without loss of refrigerant.
• If the residual pressure is too low to make the transfer
alone, a purpose-built refrigerant recovery unit must be
used.
• Compressor lubricating oil contains refrigerant. Any oil
drained from a system during maintenance must therefore
be handled and stored accordingly.
• Refrigerant under pressure must never be discharged to the
atmosphere.
• If the refrigerant circuit is opened, plug all openings if the
operation takes up to one day, or charge the circuit with
nitrogen for longer operations.
12.2.3 - Recharging liquid refrigerant
CAUTION: 30RA units are charged with liquid HFC-407C
refrigerant.
This non-azeotropic refrigerant blend consists of 23% R-32,
25% of R-125 and 52% R-134a, and is characterised by the
fact that at the time of the change in state the temperature of
the liquid/vapour mixture is not constant, as with azeotropic
refrigerants. All checks must be pressure tests, and the
appropriate pressure/temperature ratio table must be used to
determine the corresponding saturated temperatures
(saturated bubble point curve or saturated dew point curve).
Leak detection is especially important for units charged with
refrigerant R407C. Depending on whether the leak occurs in
the liquid or in the vapour phase, the proportion of the
different components in the remaining liquid is not the same.
NOTE: Regularly carry out leak checks and immediately
repair any leak found. If there is a leak in the plate heat
exchanger, this part must be replaced.
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12.2.4 - Undercharge
If there is not enough refrigerant in the system, this is indicated
by gas bubbles in the moisture sight glass.
If the undercharge is significant, large bubbles appear in the
moisture sight glass, and the suction pressure drops. The
compressor suction superheat is also high. The machine must
be recharged after the leak has been repaired.
Find the leak and completely drain the system with a refrigerant
recovery unit. Carry out the repair, leak test and then recharge
the system.
IMPORTANT: After the leak has been repaired, the circuit
must be tested, without exceeding the maximum low-side
operating pressure shown on the unit name plate.
The refrigerant must always be recharged in the liquid phase
into the liquid line.
The refrigerant cylinder must always contain at least 10% of its
initial charge.
For the refrigerant quantity per circuit, refer to the data on the
unit name plate.
12.2.5 - Characteristics of R407C
See the table below.
Saturated bubble point temperatures (bubble point curve)
Saturated dew point temperatures (dew point curve)

12.3 - Electrical maintenance

When working on the unit comply with all safety precautions
decribed in section "Maintenance safety considerations".
- It is strongly recommended to change the fuses in the units
every 15000 operating hours or every 3 years.
- It is recommended to verify that all electrical connections
are tight:
a. after the unit has been received at the moment of
installation and before the first start-up,
b. one month after the first start-up,when the electrical
components have reached their nominal operating
temperatures,
c. then regularly once a year.