CLIVET WSAN-EE 21 - Page 28

M02R40C8-00 29/07/08 page 28
SET-POINT COMPENSATIONS
The compensations are evolved functions to protect the compressors and to adapt, as far as possible, the unit operating to the
installation and use characteristics.
The compensations prolong the compressor operating time and limit the start number; to do this they delay the compressor
insertion point adding an offset.
COMPENSATED compressor activation point
non compensated compressor activation point
s
o
e
O
offset by compensation
ACTUAL set point
• The compensation on the DURATION is useful when the installation water content is limited.
• The compensation on the CHARGE is useful if the variable charge is present.
For the enabling and the configuration is necessary the parameter modification with reserved access to the service centres.
In industrial applications where is requested a temperature check is possible to disable the COMPENSATIONS.
SET-POINT CORRECTIONS
The correction aim is to optimize the unit energetic efficiency.
To do this the corrections modify the set point in a dynamic way in function of determined variables: for example in summer
operating with low external temperatures, so with a reduced charge, is possible to obtain the internal comfort also with set
point higher than standard, obtaining an higher energetic efficiency.
CORRECTION
ACTUAL or correct set point
(visible at status 1)
static set point
The static set point can so be modified in a dynamic way by two CORRECTIONS based on as many unit external factors:
• correction based on the ext. temp. / enthalpy
• correction based on the Water reset (4-20 mA signal provided by the Client)
The correct set point, to whom have been summed or removed the corrections, is named ACTUAL set-point and it is visible at
status n°1.
The STATA menu visualizes the compensation value on the ext. temperature (status 5) and WR (status 6)
For further details see the ELECTRICAL CONNECTIONS section.
SET POINT CORRECTION FOR COMPRESSOR OPERATING LIMIT
The function is active only in HEATING; it allows extending the operating limits decreasing gradually the set point when the
external temperature descends more than determined limits.
In the graph, the correction action is indicated by the curve left side (B).
The curve right side (A) represents the correction state on the external temperature (optional, see the ELECTRICAL
CONNECTIONS section).
The following data are indicatives .
T EXT
15°C
7 °C
SET POINT
4
0 °C
3
7 °C
3
5 °C
-2 °C-15 °C
A
B
DEFROSTING
The defrosting aim is to maintain the external coil free from ice that forms in winter operating: to do this the unit is periodically
commutated in “summer” operating for few minutes and fans are stopped. The defrosting phase started when the evaporating
pressure falls below a fixed value. So a count starts and when it finishes, if the temperature on the coil is lower than threshold,
occurs the real defrosting. The count is variable in function of the external temperature and the ice quantity on the coil (through
some indirect variables).
At the end of the defrosting, the unit returns automatically in the winter operating.
The defrosting frequency depends on the external temperature and on the humidity in the air:
• highest humidity = frequent defrosting
• external temperature next to 0°C = frequent defrosting
With EXTERNAL HUMIDITY PROBE cod PE2N0005 defrosting is optimized in function of the external temperature and
humidity.