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- The arrangement of power steps in “FPM” operation ensures that all compressors are activated and step
controlled before full capacity is requested.
- In “CPM” step capacity control, as the operating requirement increases, each compressor is progressively
activated to operate at full capacity before the next is activated.
As the load request declines, the number of power steps activated by the controller will be accordingly reduced.
The reduction in the request for power steps by the controller is carried out with the reverse procedure to that of
activation: as the load decreases, compressor operation is reduced by steps then shut down (“FMP” operation),
or the operation of each compressor is progressively reduced by steps then shut down (“CPM”).
The even distribution of operating hours over all compressors in the unit is ensured by selecting rotation of
operation requests.
When this function is active, the first compressor to be activated is also the first to be shut down (the compressor
that has not be activated for the longest time will in any case be activated).
The capacity control of compressors can be carried out either by steps or continuously.
During capacity step control, each solenoid valve represents a power step.
In continuous capacity step control, compressor power is adjusted by the movement of the step control cylinder.
Cylinder movement is actuated by two solenoid valves; one to increase power yield, the other to reduce it.
The cylinder moves in response to pulses by the solenoids; cylinder position and the degree of step control is
regulated by the controller, on the basis of the time configured for the entire cylinder stroke.
Shutdown and start-up of compressors are always carried out at 25% of capacity.
5.2.14 Low temperature kit (option)
5.2.14 Low temperature kit (option)
5.2.14 Low temperature kit (option)
5.2.14 Low temperature kit (option)
5.2.14 Low temperature kit (option)
By means of the controller, condensation pressure can be maintained within a predefined operating range.
When the outdoor temperature decreases it is possible to maintain the condensation pressure within the predefined
operating range reducing the air flow on condenser.
Condensation control can be activated in chiller only and heat pump units; this function remains active only
during chiller mode operation.
In heat pump mode operation, condensation control is disregarded; fan operation is therefore forced to a maximum.
If the controller regulates several compressors, the microprocessor will control the condensation pressure on the
basis of the greater signal of those read.
The fan speed is regulated by the controller which reduces also to a minimum the problems related to the
electromagnetic compatibility of circuit.
The speed control is active in the range 40 – 100 % of nominal speed. Fan outlet control starts the fans always at
40% of nominal speed.
5.2.15 Changeover between chiller and heat pump modes
5.2.15 Changeover between chiller and heat pump modes
5.2.15 Changeover between chiller and heat pump modes
5.2.15 Changeover between chiller and heat pump modes
5.2.15 Changeover between chiller and heat pump modes
The changeover between chiller and heat pump operating modes is possible at all times, caused by an external
signal with digital input, by keyboard or by serial signal. The changeover must be seasonal only and with unit in
“OFF” position.
Before starting up the unit in the selected mode, whatever the cause of the changeover, the controller disables
the compressor outlets, and will wait for the minimum delay time configured in the factorye to elapse.
The unit works only with inlet water temperature control (or return from the system).
5.2.16
5.2.16
5.2.16
5.2.16
5.2.16 Defrosting (heat pump only)
Defrosting (heat pump only)
Defrosting (heat pump only)
Defrosting (heat pump only)
Defrosting (heat pump only)
When the units work as heat pump evaporator pressure is checked to avoid that falls below the set point.
The evaporating pressure control is active only when the heat pump unit operates in heating.
When the unit is working in heating mode (winter operation), finned coil is operating as evaporator, cooling and
dehumidifying external air. Depending on external air temperature and humidity, some condensate or frost could
appear on the finned coil reducing the air flow and the heat exchange surfaceand may cause severe damage to
the heat exchanger.
During heat pump operation of an air/water unit, this function prevents (or eliminates) the build-up of frost on the
condensing/evaporating coil.
In units comprising several compressors, defrosting can be performed on the entire unit or on each separate
Summary of Contents for KAPPA V 2001
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