Carel PRK300D0E0, User Manual, Page: 89 / 104

89
ENG
pRack +0300025EN rel. 1.3 - 17.12.2015
control the CO
2
condenser using the fans or the new EVS system:
Note: carefully check the pressure control settings; for general
uniformity of the software, automatic set point selection is not featured
for the diff erent types of control and diff erent types of refrigerant. For
example, the suggested default set point for the low temperature
compressors is 3.5 bars; in a cascade system (subcritical CO
2
) with R744
natural refrigerant, the reference pressure values are around 11 bars.
Together with the set point, the probe limits and probe alarm thresholds
will be correctly confi gured.
•
Cascade, 2 suction lines, 2 condenser lines (external driver for managing
the heat exchanger on the second line), single board;
I/ O
S2 S1
EVD
evolution
EEV
S3
FBUS
I/ O
I/ O
pR300
Fig. A.m
•
Cascade, 2 suction lines, 2 condenser lines (built-in driver for managing
the heat exchanger on the second line), single board;
I/ O
I/ O
I/ O
EEV
pR300
Fig. A.n
•
Cascade, 2 suction lines, 2 condenser lines (built-in driver for managing
the heat exchanger on the second line), double board;
I/ O I/ O
I/ O
S2 S1
EVD
evolution
EEV
S3
FBUS
pL A N
C1
NO1 NO2 NO3
C1 C4
NO4 NO5 NO6
C4 C7
NO7
C7
NO8
C8
NC8
G G0 U1 U2 U3 GND +VDC +V
term
GND +5 V
REF
U4 GND U5 GND VG VG0 Y1 Y2 Y3 Y4 ID
1
ID
2
ID
3
ID
4
ID
5
ID
6
ID
7
ID
8
ID
C
1
J1 J24 J2 J3 J4 J5
J14
J10
J13 J12
J15
F i e l d B u s c a r d B M S c a r d
J11 pLAN
J25 BMS2 J26 FBus2
4 3 2 1
pR300
C1
NO1 NO2 NO3
C1 C4
NO4 NO5 NO6
C4 C7
NO7
C7
NO8
C8
NC8
G G0 U1 U2 U3 GND +VDC +V
term
GND +5 V
REF
U4 GND U5 GND VG VG0 Y1 Y2 Y3 Y4 ID
1
ID
2
ID
3
ID
4
ID
5
ID
6
ID
7
ID
8
ID
C
1
J1 J24 J2 J3
J4 J5
J14
J10
J13 J12
J15
F i e l d B u s c a r d B M S c a r d
J11 pLAN
J25 BMS2 J26 FBus2
4 3 2 1
pR300
Fig. A.o
•
Cascade, 2 suction lines, 2 condenser lines (built-in driver for managing
the heat exchanger on the second line), double board;
I/ O I/ O
I/ O
EEV
pL A N
C1
NO1 NO2 NO3
C1 C4
NO4 NO5 NO6
C4 C7
NO7
C7
NO8
C8
NC8
G G0 U1 U2 U3 GND +VDC +V
term
GND +5 V
REF
U4 GND U5 GND VG VG0 Y1 Y2 Y3 Y4 ID
1
ID
2
ID
3
ID
4
ID
5
ID
6
ID
7
ID
8
ID
C
1
J1 J24 J2 J3 J4 J5
J14
J10
J13 J12
J15
F i e l d B u s c a r d B M S c a r d
J11 pLAN
J25 BMS2 J26 FBus2
4 3 2 1
pR300
pR300
Fig. A.p
A2.2 Pumped
Less used than traditional cascade subcritical systems, this solution
limits the use of HFC refrigerants to the equipment rooms. The medium
temperature units are supplied with pumped liquid CO
2
, while the low
temperature units are fi tted with expansion valves. The CO
2
is cooled
by a dedicated chiller (NH3 or r134a) inside a tank, normally with a tube
bundle evaporator. In addition to traditional systems, these also include
management of the pumps that deliver the liquid CO
2
to the medium
temperature evaporators, where it does not expand but rather is only
superheated and returns to the receiver in a semi-liquid state.
Fig. A.q
Board with
pLAN address 1
Board with
pLAN address 1
Board with
pLAN address 1
Board
with
pLAN
address 2
Board with
pLAN address 1
Board with
pLAN
address 2