M03Q40G6-03 30/07/08
pag
31
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.
CIRCULATION PUMP
The pump is always activated with the units ON.
The delivery capacity is variable to soften the thermal shock to the compressors when the plant temperature is close to the
threshold limits.
Delivery capacity depends on the intake temperature:
•
SUMMER: high water temperature reduces delivery
•
WINTER: low water temperature reduces delivery
CIRCULATION PUMP – CONDENSER (RUNNING WATER)
The pump is started BEFORE the compressor start and stopped AFTER the condenser stop.
SET POINT
SET POINT
SUMMER - WINTER
The thermoregulator manages two set points:
•
SUMMER set-point for cooling (parameter 32)
•
WINTER set-point for heating (parameter 33)
The control is performed on the OUTLET TEMPERATURE, comparing it with the actual set-point value (visible at status 1).
SET-POINT CALCULATION:
•
desired medium outlet water temperature = 7°C
•
Project temperature differential = 5°C (that is inlet water = 12°C)
•
¼ of the project temperature differential = 5 / 4 = 1.25°C
•
set-point to be set = 7 – 1.25 = 5.7°C
