Emerson XM670, Инструкция по установке и эксплуатации

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8 • XM679K I&O Manual 026-1218 Rev 4
6 Electronic
Expansion Valve
Menu (For Model
XM679 Only)
1. Enter the programming mode by pressing the SET
and DOWN buttons for a few seconds
(measurement unit starts blinking).
2. Press the UP or DOWN key until the controller
displays the EEU label.
3. Press SET . You are now in EEV function menu.
7 Controlling Loads
7.1. Solenoid Valve
The regulation is performed based on the temperature
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
Section 8,
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 temperature reaches the setpoint value
again.
In case of fault in the thermostat probe, the opening
and closing time of the solenoid valve are configured
by Con and CoF parameters.
7.2. 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
available only with electronic expansion valve by
selecting 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 7-1
).