Maersk Container Industry Star Cool SCI-20 Operating And Service Manual page 12

The below figure indicates the ranges for the capacity.
-100
-100%
cooling
If there is a limiter active on the unit then the compressor speed will be slower and the unit will op-
erate with reduced capacity. When a limiter is active, it will be shown in the status line on the main
display window. The type of limiter can then be seen in the Information menu
Limiter types:
• TC, limits the maximum condenser pressure (and temperature) and is typically active during
pull down. If the unit is lacking capacity compared to other Star Cool units, clean the condens-
er coil, check Pdis, and check CFM for proper operation.
• IFC, limits the maximum current draw from the FC. Is typically active during pull down if the
ambient temperature is over 25°C (77°F). If the unit is lacking capacity compared to other Star
Cool units, see AL 511 for trouble shooting and check the refrigerant level (overcharged).
• TFC, limits the maximum internal FC temperature. Is typically active during pull down if the
ambient temperature is over 40°C (104°F). If the unit is lacking capacity compared to other
Star Cool units, see AL 517 for trouble shooting.
• T0, ensures a minimum evaporator pressure and is rarely active. If this limiter is active for
more than 2 minutes, check the refrigerant level (undercharged), check Psuc and Tsuc, check
Vexp and LP valve plate.
• ITOT, limits the current draw in the unit by reducing the compressor speed. Is typically ac-
tive during pull down if the ambient temperature is over 40°C (104°F). From 13.5 A the al-
lowed frequency raise on the compressor is reduced in steps and from 17.5 A the frequency is
decreased as much as possible to avoid AL 421 from stopping the unit and the circuit breaker
from being triggered.
There can be multiple limiters activate simultaneously. The most critical limiter will be shown. The
largest of the factors is used as the active limiter. If the limiter factor is higher than the requested
capacity change, the capacity is actually reduced instead of increased. If, for example, the ambient
temperature is very high, the requested capacity may increase the FC temperature over its limits
and so the limiter will reduce the capacity until a safe and stable operation condition for the FC has
been reached.
System Capacity
Heating %
-20
Cool eco Cool PWM
-20%
Cooling %
10
Heat
+10%
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100
Capacity %
100%
heating
, line I40.