Application guidelines
47
FRCC.PC.014.A4.22
In installations with good oil return and line
runs up to 66 ft, no additional oil is required. If
installation lines exceed 66 ft, additional oil may
be needed. 1 or 2% of the total system refrigerant
charge (in weight) can be used to roughly define
the required oil top-up quantity but in any case
the oil charge has to be adjusted based on the oil
level in the compressor sight glass.
When the compressor is running under stabilized
conditions the oil level must be visible in the
sight glass.
The presence of foam filling in the sight glass
indicates large concentration of refrigerant in the
oil and / or presence of liquid returning to the
compressor.
The oil level can also be checked a few minutes
after the compressor stops, the level must be
between ¼ and ¾ of sight glass.
When the compressor is off, the level in the sight
glass can be influenced by the presence of refrig-
erant in the oil.
Always use original Danfoss POE oil 160SZ from
new cans.
Top-up the oil while the compressor is idle. Use
the schrader connector or any other accessible
connector on the compressor suction line and
a suitable pump. See News bulletin «Lubricants
filling in instructions for Danfoss Commercial
Compressors».
Oil level checking and
top-up
Commissioning
The system must be monitored after initial start-
up for a minimum of 60 minutes to ensure proper
operating characteristics such as:
• Proper metering device operation and desired
superheat readings
• Suction and discharge pressure are within
acceptable levels
• Correct oil level in compressor sump indicating
proper oil return
• Low foaming in sight glass and compressor
sump temperature 18°F above saturation tem-
perature to show that there is no refrigerant
migration taking place
• Acceptable cycling rate of compressors, includ-
ing duration of run times
A short cycling protection is provided in the
CDS302 frequency converter. It is factory preset
“enabled” with the following parameters in:
28.01
interval between 2 starts: 300 secondes
28.02
minimum run time: 12 seconds
This minimum run time is set to guaranty long
enough running time at start up in order to cre-
ate enough refrigerant flow velocity in the system
to recover the oil to the compressor sump.
• Current draw of compressor within acceptable
values (RLA ratings)
• No abnormal vibrations and noise.
Optional relay card
In some situation, an optional relay card is
needed and installed on the frequency convert-
er. This will give access to extra parameters that
will have to be set according to the application
needs. These settings can be done directly to the
frequency converter or downloaded to it (via a
LCP for example).
Afterwards, if the relay card is removed and the
frequency converter is powered-up without the
relay card in place, the settings will be loosed and
reset to factory settings. Therefore, during com-
missioning or card replacement, it is important to
not power-up the frequency converter while the
relay card is not in place.
suction to ensure adequate motor cooling
and no liquid refrigerant is being returned
directly to the compressor.
Installation