T-CU19-JAN24-1
Page 18
Inverter compressor start-up:
Compressor is managed to start-up by adapting operating
speed to guarantee that the desired conditions and
excellent lubrication are reached very quickly. For this
reason, when starting the compressor is operated at a
settable fixed speed (Cag52) for the minimum ON time.
During this stage, the out-of-envelope alarm is disabled,
but speed control remains active if approaching or
exceeding zone 2 (maximum compression ratio), 3
(maximum condensing pressure) or 4 (current limit).
If 45 seconds after compressor start-up, the pressure
differential is less than 0.2barg higher than the value
measured at start-up, the controller stops the compressor
and generates a “No compressor start
-
up” alarm. This
alarm is automatically reset, and the controller tries to start
the compressor five times after a 30 second delay. After
the fifth attempt, the alarm is no longer automatically reset.
Figure 12: Compressor Startup Curve
The corresponding parameters are in loop: Compressors ->
Advanced -> masks Cag50, Cag51, Cag52:
Pressure differential during
start-up
•
The BLDC compressor
cannot start if the pressure
differential is greater than 9.0barg
. This limit depends
on the maximum current delivered by the inverter. As
soon as the pressure differential falls below the
minimum threshold, the compressor can start.
•
The corresponding parameters are in loop:
Compressors -> Advanced -> mask Cag49:
•
When the pressure differential is 8.5barg (fixed
value), the compressor is ready to start.
Minimum pressure differential for lubrication
The min. pressure differential threshold for correct
lubrication is related to the type of BLDC compressor and
cannot be modified. The low-pressure differential alarm is
generated when the difference between condensing
pressure and evaporation pressure (DeltaP) remains below
the limit defaulted for a set time, and consequently
excellent lubrication is not guaranteed. The alarm stops the
compressor and is reset automatically. The alarm is not
active during defrosting.
The corresponding parameters are in loop: Compressors ->
Advanced-> mask Cag55:
Times
Time management includes a minimum On time, a minimum
Off time and a minimum time between two consecutive
starts. These parameters can be modified under
Compressors -> Configuration -> mask Caf35:
Figure 13: Times Control for Compressor Startup
