Application Limits In Part-Load Operation; Operating The Crii Capacity Control With The System Controller; Control Via Analogue Signal - Bitzer 4PTEU-6LK Technical Information

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%
140
p [bar]
h
120
100
80
Motor 2
60
40
20
10 20 30
-30 -20 -10
Fig. 9: Application limit 6FTEU-35LK to 6CTEU-50LK, 33%
t Evaporation temperature (°C)
o
Δt Suction gas superheat (K)
oh
p Suction pressure abs. (bar)
o
p High pressure abs. (bar)
h
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.
KT-102-1
Motor 1
t = 10 K
oh
p [bar]
40 50 60
o
t [°C]
o
0 5 10 15 20
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 .. 10 V
100%
80%
60%
*
CR
min
40%
20%
CR
min
0%
0 2 4
0,2 1
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).
6 8 10
U [V]
12
11