Emerson E2 Manuel D’Utilisation

When an MCC application runs for the first time, it 

undergoes a "Learning Mode" period to collect data on the 
chiller stages. During Learning Mode, the MCC will con-
trol the chilled water temperature, but it will purposely 
cycle the chiller stages in different combinations to mea-
sure the effect they have on the temperature input value.

The Learning Mode lasts for several minutes. After 

Learning Mode ends, the MCC will require up to 24 hours 
of operation before compressor cycling is operating at 
maximum efficiency. If compressor cycling seems too fre-
quent after 24 hours of operation, you may reduce com-
pressor cycling by changing the Control/Cycles parameter.

The MCC has one parameter with five preset settings 

to allow users to alter temperature control performance or 
compressor cycling frequency. The default setting, "Mod-
erate Control," seeks to balance good temperature control 
with efficient cycling. If tighter control is needed, setting 
the field to "Tight Control" or "Tightest Control" will 
increase the application's reaction to temperature changes, 
resulting in tighter control (usually at the expense of more 
frequent cycling). If fewer compressor cycles are desired, 
setting the field to "Less Cycling" or "Least Cycling" will 
decrease the number of cycles but also increase the 
amount of fluctuation in the temperature control.

MCC can utilize up to 32 compressors for maintaining 

the chilled supply temperature at a user specified setpoint. 
This is accomplished by either turning on or off any of the 
compressors defined in the application. As Supply Tem-
perature rises above setpoint, compressors will be turned 
ON. As Supply Temperature falls below setpoint, com-
pressors will be turned OFF. The Chilled Supply Tempera-
ture sensor should be located very close to the Compressor 
Control Unit so no minimal control lag is expected to be 
present.

When a compressor has been shut down on an alarm, 

the compressor will remain out of the active rotation until 
the alarm has been cleared. Additionally, the user will 
have the option of specifying that the alarmed compressor 
be re-tried the next time it comes up in the rotation. To 
prevent damage to a compressor, the user will have the 
option of specifying a number of trips per day before the 
compressor is permanently locked out. Once this condition 
has occurred, the compressor alarm will require a manual 
reset to bring it back into the active rotation.

The controller will monitor the Chilled Differential 

Pressure and if it falls below a user specified threshold, the 
controller will start to shut down compressors one at a 
time based on a user specified time delay. This shutdown 
operation will be suspended if the Chilled Differential 
Pressure rises above a user defined setpoint.