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8.2 Configuration list
The pCO1 boards allow managing both “D
X
” direct expansion and “CW” water coil a
ir-conditioning units.
When started, the program recognises the board type and size, consequently prearranging inputs and
outputs, also based on the air-conditioning unit type (DX or CW) established in the Manufacturer branch.
Note:
For the input/output configuration see the electrical diagram.
8.3 Accessories
8.3.1 Electronic expansion valve
The EVDriver module for the control of the electronic expansion valves (EEV) for LAN network allows the
inlet overheating control for amore efficient and versatile operation of the refrigerating unit.
Efficient because the optimisation and the stabilization of the refrigerant flow to the evaporator increase the
performance of the installation assuring at the same time the safety (less activations of the low pressure
switch,
less backflows of the refrigerant to the compressor,…).
Moreover, if the EEV has been properly dimensioned, using the floating or low setpoint condensation (and
evaporation) pressure increase remarkably the efficiency of the installation allowing less energy consumption
and a better refrigerating yield.
Versatile because using the electronic expansion valve implies the possibility to manage refrigerating units
with very different capacities and in different operating conditions.
The use of the electronic expansion valve implies the installation not only of the EVDriver or the expansion
valve themselves, but also of a temperature sensor and a pressure transducer, both of them placed at the
end of the evaporator on the refrigerant side (on the compressor inlet pipe). Refer to the following diagram
for a better understanding of the typical installation layout.
The base principle of the new control algorithm aims at the installation stability combined with, when
possible, a quick achievement of the overheating steady state.
In this sense, the priorities to be considered for an optimum control of the refrigerating installation are a high
and constant refrigerating yield rather than an extremely low and stable overheating.
The heart of the control is a PID controller that features coefficients that can be set for the overheating.
The additional controls are:
LOW (Low overheating with integral time and adjustable threshold)
LOP (Low evaporation pressure, operating actually only on transients, with integral
time
and adjustable threshold)