Single compressors
Operating conditions
Oil return management
function (single
compressor)
An insufficient oil level can be the result of oil
depositing itself in pipes and heat exchangers
or low velocity of compressors. The oil return
management could be achieved by increasing
velocity for short periods, at regular time
intervals.
CDS803 integrates oil return management
function together with compressor internal
lubrication protection.
Internal lubrication protection: If compressor
runs below 40 rps (ORM Min Speed Limit, 28-15)
for more than 19 minutes (low speed running
time, 28-11), then CDS803 internal lubrication
function will accelerate compressor speed to
40 rps (minimum ORM Boost Speed, 28-17) for
1 minute (minimum duration, includes ramp
up time, 28-13) to guarantee compressor inner
parts get lubricated. In case slow acceleration
condition, please make sure compressor maintain
minimum speed 40 rps (80Hz) for at least 1
minute running.
Oil return function: To double ensure well
lubrication, compressor speed will boost to 40
rps (minimum ORM Boost Speed, 28-17) at a fixed
time intervals (as programmed in parameter 28-
12, default 24 hrs) any way. OEM could set 28-17
to a higher speed, such as 70 rps to secure oil
management
According to different application requirements,
OEM can either add oil separator (including to
add more oil in the system) or adjust oil return
parameters or might need both actions to keep
oil safety for compressor.
Oil management related parameters, 28-11, 28-
12, 28-13,28-15, 28-17 could also be programmed
by OEM.
Considering oil return risk, a split system
with more than 10 m piping length requires
mandatory application approval by Danfoss
application specialists.
Use the “oil level switch” accessory with the
appropriate compressor housing having the
fitting preassembled and refer to the “VZH hybrid
manifolding” section at the end of this document.
Oil return management
in hybrid manifolding
ID
Name
Factory setup
Unit
2810
Oil return management
ON
2811
Low speed running time
19
min
2812
Fixed boost interval
24
h
2813
Boost duration
60
s
2815
ORM min speed limit
80
Hz
2817
ORM boost speed (Hz)
80
Hz
27
FRCC.PC.034.A2.02
Application Guidelines
Содержание VZH Series
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