D-EOMCP00104-14_01EN
Operating Manual
26/35
EWYD_BZ
5.23.2.2 VSD in heating mode
5.23.2.2.1 Control of evaporation temperature
When the system is operating in heating mode to control the evaporation temperature the proportional gain is
negative (the higher the input the lower the output).
Controlled
Variable
Action
Set Point
Dead Band
Regulation Band
Max
0
-Max
Fig. 16
– Proportional action of VSD PID in heating mode
5.23.2.2.2 Control of pressure ratio or temperature differences
When the system is operating in heating mode to control the pressure ration the proportional gain is positive (the
higher the input the higher the output).
5.23.3
Speedtroll
A mixed step-VSD control are used; the first fans step are managed using a VSD (with related PID control), next steps
are activated as in the step control, only if the cumulated stage-up and stage-down error is reached and the VSD output
is at maximum or minimum respectively.
5.23.4
Fans control at startup in heating mode
At the compressors start in heating mode fans are started before that the compressors begin their normal start up
sequence if the outside ambient temperature is below a fixed temperature of 10.0°C (50.0F). If the condensation contr ol is
either speedtroll or fantroll each step is activated after a fixed delay of 6 seconds. The control is released to automatic
control if the outside ambient temperature is greater than a fixed threshold of 15.0°C (59.0F).
5.24 Other functions
The following functions are implemented.
5.24.1
Hot Chilled Water Start
This feature will allow the unit startup also in case of high evaporator outlet water temperature.
It will not allow the compressors loading above an adjustable percentage until the evaporator leaving water temperature
falls below an adjustable threshold; another compressor is enabled to start when the others are limited.
5.24.2
Fan Silent Mode
This feature will allow to reduce unit noise limiting fans speed (only in case of VSD fan control) on the base of a ti me
schedule. A maximum output voltage for the VSD could be set for FSM operations (default value 6.0V).
5.25 Unit and compressors status
In the following tables it will be possible to find all the configured unit and compressors status with some details explaining
the status.
Unit Status code
Interface status label
Explanation
0
-
Not reachable.
1
Off Alarm
Unit is off due to a unit alarm.
2
Off Rem Comm
Unit is off from Remote Supervisor.
3
Off Time Schedule
Unit is off due to time schedule.
4
Off Remote Sw
Unit is off from remote switch.
