Su Start Unloading; Compressor Cooling; Oil Heater; Switching Times Of The Motor Contactors At Compressor Start - Bitzer KT-230-2 Technical Information

5.1.2

SU start unloading

The compressor module switches the solenoid valve
and ensures an unloaded compressor start.
When start unloading is fitted, one less cylinder bank is
available for capacity control. The control range for ca-
pacity control is reduced accordingly.
5.1.3

Compressor cooling

The compressor module switches the additional fan on
from a discharge gas temperature of 120°C and off
again at 100°C. When the discharge gas temperature
reaches 135°C, the RI is initially switched on intermit-
tently, from 140°C it is in continuous operation. As long
as RI is active, the compressor can only be operated in
the upper part-load range. The limit for 4-cylinder com-
pressors is 50% and for 6-cylinder compressors 66%.
In the lower part-load range, the module switches on
the additional fan for engine cooling as required, below
50% for 4-cylinder compressors and below 33% for 6-
cylinder compressors.
5.1.4

Oil heater

The compressor module switches the oil heater on
when the compressor is at a standstill and off again
during operation.
5.1.5 Switching times of the motor contactors at
compressor start
The switch-on and switch-off times of the motor con-
tactors are programmed into the compressor module.
When delivered, the timer is configured for the built-in
motor:
Direct-online-start: The contact at terminal CN2:2 (K1
Control) closes 1 s after the start-up signal and opens
when the compressor is switched off. The contact at
terminal CN2:1 (K2 Control) is not assigned.
Part winding start: The contact at CN2:2 (K1 Control)
closes 1 s after the start signal. The contact at CN2:1
(K2 Control) closes 0.5 s thereafter. Both contacts re-
main closed until the compressor is switched off.
Star-delta-start: The contact at terminal CN2:2 (K1
Control) closes 1 s after the start signal and opens after
a further 1.5 s. The contact at terminal CN2:1 (K2 Con-
trol) closes 1.5 s after the start signal and remains
closed until the compressor is switched off.
Operation with frequency inverter (FI): The signal out-
put CN2:2 (K1 Control) switches the FI on.
The selected terminal assignment on the module pre-
vents a short circuit from occurring if the switching
KT-230-2
times set in the module do not correspond to the motor
used. Set the time switch appropriately for the motor
see chapter Selecting the motor start function, page
28.

5.2 Monitoring and protective functions

The compressor module monitors the signals from sev-
eral sensors, which can be attached to the compressor,
suction or discharge gas line:
Monitored function
Motor temperature
(standard)
Discharge gas temper-
ature (standard)
Application limits (op-
tion):
Condensing and evap-
oration temperature
Low pressure (option)
High pressure (option)
Oil supply (standard)
Compressor switching
frequency (standard)
The compressor module compares the measured val-
ues with programmed data. It outputs messages via
Modbus and signals the operating status via LEDs in
different colours. In case of operation outside the oper-
ating limits, low oil or excessive motor temperature, the
compressor is switched off, see chapter Protective
functions, page 25. The module issues warnings if the
compressor starts too often or if the minimum running
time or the minimum downtime is not reached.
Sensor
Motor temperature sensor
(R1 .. R6)
Discharge gas temperature
sensor (R7)
Low- and high-pressure
transmitters (B7 and B6)
Low-pressure transmitter
(B7)
High-pressure transmitter
(B6)
Oil level monitoring with
OLC-D1 (F4)
or
differential oil pressure
monitoring with DP-1 (F4)
integrated in CM-RC-01
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