Technical data

8 • XM670K-XM679K I&O Manual 026-1218 Rev 0 19-DEC-2012
7 Electronic
Expansion Valve
Menu (For Model
XM679K Only)
1. Enter the programming mode by pressing the SET
and DOWN buttons for a few seconds (measure-
ment unit starts blinking).
2. Press the UP or DOWN key until the controller dis-
plays the EEU label.
3. Press SET. You are now in EEV function menu.
8 Controlling Loads
8.1. Solenoid Valve
The regulation is performed based on the tempera-
ture measured by the thermostat probe that can be a
physical probe or a virtual probe obtained by a
weighted average between the two probes (see Sec-
tion 9, Parameters List) with a positive differential
from the setpoint. If the temperature increases and
reaches setpoint plus the differential, the solenoid
valve is opened and then it is closed when the tem-
perature reaches the setpoint value again.
In case of fault in the thermostat probe, the open-
ing and closing time of the solenoid valve are config-
ured by Con and CoF parameters.
8.2. Standards Regulation
and Continuous
Regulation
The regulation can be performed in two ways:
• Standard regulation is reaching the best superheat
via a classic temperature regulation obtained using
hysteresis.
• Continuous regulation permits the use of the valve
to realize a high performance temperature regulation
with a good factor of superheat precision. This only
can be used only in centralized plants and it is avail-
able only with electronic expansion valve by select-
ing the CrE=Y parameter.
In any case, the regulation is performed via the PI
regulator that gives the opening percentage to the
valve via PWM modulation explained as follows:
Opening Percentage is obtained from the average of
the Opening Time with respect to the CyP time period
(see Figure 8-1).