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Control logic
38
AB444226142054en-000101
The oil management control logic must include 2 steps.
CC-000103
Low oil level
>5 sec
Normal
Low oil level
operation
Step 1 (oil boost) if oil level sensor detects low
level for more than 5 seconds, oil is trapped in
the system. Oil boost is activated (VS speed is
increased). It increases refrigerant velocity in the
system and recovers oil. TD1 is the maximum
time to complete step 1. If oil is not recovered
within TD1 switch to step 2. If oil is recovered
within TD1, the compressor will come back to
normal operation.
Step 1 Oil boost function description
Return oil trapped in the system to compressor
by increasing refrigerant mass-flow in the system.
Enter condition: Low oil level in VS compressor
detected by oil level sensor.
Cancel condition: High oil level in VS compressor
detected by oil level sensor.
OR
t1>TD1, Oil boost duration exceeds Maximum Oil
boost duration
TD1*
CC-000104
t1
2
OL
1
FB
VS Cp
Less than every
20min (TD2*)
Max 45
sec (TD1*)
Oil
Boost
Step 1
TD2 is the minimum interval between two step
1. In case of low oil level detection within a time
<TD2, switch to step 1.
Step 2 (Protection) If the oil is still lower than
the limit after having completed step 1, or if the
oil level drips again
within a time <TD2, the controller must move
forward in protection mode and stop the system
in alarm.
Control sequence:
1.
At initial state, VS (variable speed
compressor) is ON.
2.
Low oil level detected in compressor. Reset
and Start t1.
3.
VS compressor speed must increase to
Fboost
4.
When High oil level detected in VS
compressor speed must be decreased to the
initial speed
•
Reset and start t2
•
Reset
t2
3
VS Cp
FB
OL
TD1*
Oil level not
Protection
recovered
Step 2
Variable speed compress
FBoost
Oil lack
TD1 Max.
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