KT-230-1
13
Optional temperature sensor R11
An optional PT1000 temperature sensor can be con-
nected to the control. The data of the temperature
sensor are logged but they do not influence the control
and the monitoring.
Electrical connection: Connect the cables of the CM-
RC-01 to terminal strip CN11, terminals 1 and 2, ac-
cording to the schematic wiring diagram.
The BEST Software detects this sensor automatically.
6.3
Controlling the CRII using the system controller
CRII can be controlled via Modbus or an analogue sig-
nal. Compressor operation at reduced capacity is only
admissible within the part-load limits for the respective
refrigerant. Minimum residual capacity: 10%. Program
the system controller accordingly. Application limits,
see BITZER Software and Technical Information
KT-101.
6.3.1
Control via analogue signal
The compressor capacity is regulated via a DC voltage
signal. This type of control is mainly suitable for sys-
tems with simple controllers which are equipped with
an output for 0 to 10 V and a relay, and for use in com-
bination with the BEST Software on Modbus connec-
tion.
• Connection to terminal strip CN13, terminals 1 and
2.
• Control signal: 0 to 10 V direct current voltage for an
analogue output of the system controller
• Control accuracy: ±0.5% at 100%
• Linear control characteristic, see figure.
CRII
0
2
4
6
8
10
12
U [V]
0 .. 10 V
100%
CR
min
CR
min
1
80%
60%
40%
20%
0%
0,2
*
Fig. 4: Control characteristic
• CR
min
: The compressor capacity can be reduced
from 100% to 10% if each cylinder head is equipped
with CRII capacity regulators.
• CR
min
* and dashed line: The range of control is re-
duced if not every cylinder bank is equipped with ca-
pacity regulators. The minimum capacity step of 50%
is the lower regulation limit for 8-cylinder com-
pressors and for 4-cylinder compressors with one
capacity regulator. In this case, the CM-RC-01 regu-
lates to a residual capacity of 50% as soon as the
control signal falls below 5 V.
6.3.2
Control via Modbus interface
Insert or connect the cable to terminal strip CN14. See
schematic wiring diagrams.
In this case, the operating parameters can be mon-
itored via Bluetooth by means of the BEST Software.
6.4
Connecting the operation monitoring device with
the BEST Software
• Connect the BEST interface converter to terminal
strip CN14 (Modbus).
In this case, the capacity control must be predefined via
the analogue signal on terminal strip CN13.
The BEST Software can access the compressor control
module via a Bluetooth interface, see chapter Commu-
nication via the BEST Software, page 14. This inter-
face is not available upon market launch.
7
Protective functions
The green LED is on during normal operation. The
LEDs can be seen through a sight glass in the module
housing, see chapter Dimensional drawings, page 6.
Before the measured value of a sensor reaches a crit-
ical threshold, the compressor control module outputs a
warning signal via the Modbus RS485 interface
(CN14). In this case, the yellow LED lights up. Once a
measured value is considerably outside the allowable
range, the compressor control module will immediately
switch off the motor. The red LED lights up.
The blue LED lights up when data are transmitted via
the Modbus interface.
Depending on the measured parameter, up to 3 alarm
levels are defined. These alarms are recorded and dis-
played using the BEST Software. The alarm levels
make it possible to programme a system controller in a
way that allows the compressor to be adjusted within
the application limits.
