Single compressors
Installation
Leak detection
Leak detection must be carried out using a
mixture of nitrogen and refrigerant or nitrogen
and helium, as indicated in the table below.
Never use other gasses such as oxygen, dry air
or acetylene as these may form an inflammable
mixture.
Pressurize the system on HP side first then LP
side.
Leak detection
with refrigerant
Leak detection
with a mass spectrometer
Nitrogen & R410A
Nitrogen & Helium
Vacuum pump down and
moisture removal
Refrigerant charging
Commissioning
Moisture obstructs the proper functioning
of both the compressor and the refrigeration
system. Air and moisture reduce service life and
increase condensation pressure, which causes
abnormally high discharge temperatures that
are then capable of degrading the lubricating
properties of the oil. The risk of acid formation
is also increased by air and moisture, and this
condition can also lead to copper plating. All
these phenomena may cause both mechanical
and electrical compressor failures. The typical
method for avoiding such problems is a vacuum
pump-down executed with a vacuum pump, thus
creating a minimum vacuum of 500 microns (0.67
mbar). Please refer to News bulletin
Tl1-026-0302 “Vacuum pump down and
dehydration procedure”.
For the initial charge, the compressor must not
run and eventual service valves must be closed.
Charge refrigerant as close as possible to the
nominal system charge before starting the
compressor. This initial charging operation must
be done in liquid phase as far away as possible
from the compressor. The best location is on the
liquid line between the condenser outlet and the
filter drier. Then during commissioning, when
needed, a complement of charge can be done
in liquid phase: slowly throttling liquid in on the
low pressure side as far away as possible from the
compressor suction connection. The refrigerant
charge quantity must be suitable for both
summer and winter operations.
Refer to news bulletin FRCC.EN.050 “Danfoss
Commercial Compressors recommended
refrigerant system charging practice” for more
details.
The system must be monitored after initial
startup 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 10K above saturation
temperature to show that there is no refrigerant
migration taking place
• Acceptable cycling rate of compressors,
including duration of run times.
A short cycling protection is provided in the
CDS803 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: 60 seconds.
This minimum run time is set to guaranty long
enough running time at start up in order to
create 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.
Note this compressor is equipped with
a four-pole electrical motor so the applied
frequency from the inverter will be 30 Hz for
15 rps(900 rpm) up to 200 Hz for 100 rps (6000
rpm).
39
FRCC.PC.034.A2.02
Application Guidelines
Содержание VZH Series
Страница 1: ...Inverter scroll compressors VZH028 035 044 single R410A Application guidelines http cc danfoss com ...
Страница 2: ......
Страница 3: ...Content VZH028 035 044 single compressors 4 3 FRCC PC 034 A2 02 Application Guidelines ...
Страница 43: ...Single compressors Trouble shooting 06 03 2015 page 5 43 FRCC PC 034 A2 02 Application Guidelines ...