T-CU19-JAN24-1
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Compressor Control
Control can be proportional or propor integral (P,
P+I). The corresponding parameters are in loop:
Compressors -> Regulation -> mask Cab14.
The set point is in the center of the band. Proportional
control is illustrated in
Figure 14
.
Figure 14: Proportional Control
With propor integral control, the integral time is
summed to the effect of proportional control, giving a null
control error in steady operation. This type of control is
illustrated in
Figure 15
.
Figure 15: Propor Integral Control
The integral action depends on time and the deviation from
the set point. The integral time represents how fast integral
control is implemented:
• Low values bring fast actions yet more instability
• High values bring slower actions and more stability
The values should not be set too low, to avoid system
instability. Two types of control can be set, in loop
Compressors -> Regulation -> mask Cab01
• Fixed set point: Default
• Floating set point: Only available by exploiting serial
communication with the evaporators. Serial communication
allows information to be exchanged in real time between
the controller and the MPXPRO devices.
AC Fan Speed Modulation
One of the AC fans is controlled by a phase cut modulating
device based on pressure input. The fan speed control is
factory preset with a ±3.0barg differential setting. With
this setting, the fan operation is as follows:
The meaning of the parameters that are associated with
modulating device on masks Db03, Db07, Db04, Db06 and
Dg02 are illustrated in the following graph.
The fan under FSC control will start at 100% speed for
approximately 5 seconds before starting modulates
between 45% ~ 100% of full fan speed.
Figure 16: Fan Control Curve
•
Fan control can be switched to be controlled by
external temperature probe if fault discharge pressure
transducer. Associated parameter to be changed on
masks: Dg14, Dg15.
•
Recommended fan settings to gain higher energy
efficiency as published in the Ecodesign data sheets
are as follows:
Table 14: Fan Settings for Ecodesign Data
Refrigerant
R448A/R449A/R404A
Setpoint limits (Db02)
Minimum: 10barg;
Maximum: 28barg
Setpoint (Db03)
13.5barg
Cut off enable (Db05)
No
Pressure Regulation
Differential (Db07)
5.5barg
