6
+030220575 - 1.1 - 04.12.2014
ENG
If the Smooth lines function is enabled, the algorithm tells the supervisor whether the MPXPRO is operating
with a certain margin, i.e., the suction pressure set point on the corresponding line can be increased wi-
thout jeopardising control. In detail, the MPXPRO declares that operation is suitable if the average working
superheat set point is higher than P3 + THS. The average is calculated inside the time window FSt.
Working setpoint
Superheat setpoint (P3)
Regulation setpoint
Regulation temperature
Cooling request
Smooth line status
FSt = average time window (min)
1
0
t
t1
t2
t3
t4
t5
1
0
PLt = offset under setpoint
When the average of working setpoint is higher
than the threshold P3 + TSH the Smooth line status
becomes 0, allowing suction pressure rising.
rd = setpoint differential
rd/2
TSH = superheat threshold
PHS = max superheat offset
As soon as the regulation temperature falls below the
se rd/2, an offset will be added to the superheat
setpoint in order to reduce the EXV valve opening.
Cooling status will stay active until the regulation
tewmperature does not fall below the threshold St - PLt.
Fig. 1.b
1.2 Smooth lines on MPXPRO: confi guration
The Smooth lines confi guration parameters are listed in Table 1. The basic settings are listed below, with the
parameter name and default value:
1.
enable function, default value is
PSM
= 0 (disabled);
2.
set maximum superheat off set, default value is
PHS
= 15 (K);
3.
set compressor cut-off off set, default value is
PLt
= 2 (K);
4.
set main control diff erential, default value is
rd
= 2 (K);
if smooth lines is enabled, the suggested value is
rd
= 4 (K).