Bitzer 4CTEU-30LK, Technical Information, Page: 11 / 28

KT-102-1 11
7 Application limits in part-load operation
Information
Observe information on discharge gas pressure
and operating temperatures and lubrication con-
ditions as specified in KB-130!
The application of the mechanical capacity control is
limited mainly by thermal limits of the lubricants used.
These thermal limits are monitored in dynamic and sta-
tionary operating states by the compressor module and
the defined control algorithms.
The limits of the discharge gas temperature are:
• Warning: 140°C
• Fault / Switch-off 150°C
• Reset / Unlock 135°C
6FTEU-35LK to 6CTEU-50LK, 33%
10 60 50 40 30 20
20
140
120
100
80
60
40
p [bar]
h
p [bar]
o
t = 10 K
oh
t [°C]
o
20 15 10 5 0 -10 -20 -30
Motor 1
Motor 2
Fig. 9: Application limit 6FTEU-35LK to 6CTEU-50LK, 33%
t
o
Evaporation temperature (°C)
Δt
oh
Suction gas superheat (K)
p
o
Suction pressure abs. (bar)
p
h
High pressure abs. (bar)
IQ range: independent monitoring of the
application limit by the compressor mod-
ule as a function of the discharge gas
temperature.
Tab. 4: Legend application limit
For the part-load application limits of all compressors
with CRII capacity control, see BITZER SOFTWARE
and upon request.
8 Operating the CRII capacity control with the system
controller
8.1 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 if the terminal
strip CN14 is used for the BEST SOFTWARE.
• 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. 10: Control characteristic
• CR
min
:
– 4-cylinder compressors: Starting with 100%, the
compressor capacity can be reduced to 25% (in
future to 10%) if each cylinder head is equipped
with CRII capacity regulators.
– 6-cylinder compressors: Starting with 100%, the
compressor capacity can be reduced to 33% if 2
cylinder heads are equipped with CRII capacity
regulators.
Information
From firmware- version 2.3.242.00, the min-
imum/maximum capacity control step can be
freely set in the BEST SOFTWARE (BEST
2.8.229.0 SP2) (see chapter Capacity control
CRII with the BEST SOFTWARE, page 13).