OPERATING AND MAINTENANCE MANUAL
Chapter 7 - Electronic controller
iC 215 ÷ iC 780
47
The data in this manual are not binding and they can be modified by the manufacturer without notice.
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ENGLISH
7 . 1 4 . 4
C o m p r e s s o r s p r o p o r t i o n a l c o n t r o l d i a g r a m
Compressors regulation operation diagam in chiller mode.
7 . 1 4 . 5
N e u t r a l z o n e c o n t r o l ( f a c t o r y s e t t i n g )
In chiller mode, if the reference temperature is > SDifferential, the unit’s compressors are started in sequence in
accordance with the starting time lag outside the neutral zone.
In contrast, if the reference temperature is < Setpoint, the unit’s compressors are stopped in sequence in accordance with the
stopping time lag outside the neutral zone.
Moreover, to guarantee arrival at the temperature setpoint and rotation of the compressors, if the reference temperature is
within the neutral zone, the unit’s compressors are started in sequence, respecting the starting time lag in neutral zone. Still
within the neutral zone, after a programmable time interval the controller stops one compressor and, observing the
programmed rotation, starts another. Actions in the neutral zone are performed only if at least one of the unit’s compressors
is already running.
Compressors regulator operation diagram in chiller mode:
7 . 1 4 . 6
C o m p r e s s o r s r o t a t i o n
For correct operation in the compressors time the electronic controller manages rotation of compressor starts with different
logic, selectable by means of a parameter.
The possible choices are:
•
Fixed sequence
: the first compressor to start is always the last one to stop.
•
Rotation by hours
: the compressor that will be started is the one with the lowest number of running hours,
while the first to be stopped will be the one, among the running compressors, with the highest number of
running hours.
•
Rotation by starts (factory setting)
: the compressor that will be started is the one, among those available,
with the lowest number of starts, while the first to be stopped will be the one, among the running compressors,
with the highest number of starts.
In two-circuit units it is also possible to choose whether to favour saturation or balancing of the compressors in each circuit.
7 . 1 4 . 7
F o r c e d c o m p r e s s o r s r o t a t i o n
For units that frequently operate at partial loads, the controller provides the facility to perform forced compressor rotations.
For circuits with more than one compressor although only one of which running, after programmable time the compressor is
stopped and starting of the available compressor is forced.
Step
4th Step
3rd Step
2nd Step
1st Step
OFF
St07
Temperature
St01
Decrease
Cooling capacity
Zone
Neutral
Increase
Cooling capacity
Set
Set+Diff
Temperature