14.SUCTION CONTROLS
14. 1
Suction Control:
The suction control parameters are set in the following menu:
Main menu
1.Functions Settings
2.Suction
.
c c
c c
Compressor control is linked with a suction pressure switch. The
RCK-862
plus
allows the control of up to 3 suction pressure switches with up to 6
compressors each. The digital outputs indicated as O1, O2...O6, are in charge of the on-off control (On/Off) of compressors and unloaders valves, while
the analog outputs, indicated as A1 and A2, emit a 0-10V signal for frequency inverters or other devices. The
RCK-862
plus
controls up to three
unloader valves per compressor, having a Control Mode for variable compressors such as the Bitzer CRII.
Note
:
Alarms on the discharge pressure switches can also act on the suction compressors.
14.2 Compressor modulation On/Off:
Each compressor manufacturer has its own way of controlling capacities in its compressors. The most common compressors have two stages of
operation: on ir off. In this case, on/off modulation is used. When there are compressors with the possibility of regulating their capacity by means of
actuations of step-type unloaders, the type is selected according to the options below:
On/Off (On / Off)
- Compressor that uses only one digital output (relay) for its actuation.
On/Off 50 I 100
- A main output and an auxiliary output are linked for 3-stage compressor control.
On/Off 33 I 66 I 100
- A main output and 2 auxiliary outputs are linked for 4-stage compressor control.
On/Off 50 I 75 I 100
- A main output and 2 auxiliary outputs are linked for 4-stage compressor control.
On/Off 25 I 50 I 75 I 100
- One main output and 3 auxiliary outputs are linked for 5-stage compressor control.
An activation mode is defined (
1.2.1.28
- (
33
)) to determine the sequence of operation of the control outputs according to the construction of the
compressor and connected with the modulation of the On/Off compressors.
The main menu output, the first to be actuated and the last to be shutdown, is normally used to drive the compressor motor. While the auxiliary outputs
are normally used to start or stop, an unloader valve is used for regulating the compressor capacity.
The
RCK-862
plus
has 3 activation modes as shown in the table below:
Incremental Mode
Modulation ON/OFF 33 I 66 I 100
Modulation ON/OFF 50 I 75 I 100
Modulation ON/OFF 25 I 50 I 75 I 100
Modulation ON/OFF 25 I 50 I 75 I 100
Modulation ON/OFF 25 I 50 I 75 I 100
Modulation ON/OFF 33 I 66 I 100
Modulation ON/OFF 50 I 75 I 100
Modulation ON/OFF 33 I 66 I 100
Modulation ON/OFF 50 I 75 I 100
Modulation ON/OFF 50 I 100
Capaciity
Off
Off
Off
Off
Off
Off
Off
Off
Off
Off
Off
Off
50%
50%
50%
33%
33%
33%
66%
66%
66%
100%
100%
100%
100%
100%
100%
100%
100%
100%
50%
50%
50%
25%
25%
25%
50%
50%
50%
75%
75%
75%
75%
75%
75%
100%
100%
100%
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Capacity
Main
Main
Main
Main
Main
Main
Main
Main
Main
Main
Main
Main
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 1
Aux 2
Aux 2
Aux 2
Aux 2
Aux 2
Aux 3
Aux 3
Aux 3
Aux 3
Aux 3
Aux 3
Aux 3
Aux 3
Aux 2
Aux 2
Aux 2
Aux 2
Aux 2
Aux 2
Aux 2
Aux 3
Aux 3
Aux 3
Aux 3
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Modulation ON/OFF 50 I 100
Modulation ON/OFF 50 I 100
Unloader Mode
Selective Mode
Key:
- Output on
- Output off
Example:
For a compressor with two unloaders where each valve removes 33.3% of the compressor capacity, you can select the compressor
modulation as On/Off 33 I 66 I 100 (parameter
1.2.x.22
- (
27
)). An output is defined for the compressor motor, associated with the main output
(
1.2.x.37
) and two auxiliary outputs for the unloader valves (
1.2.x.38
and
1.2.x.39
) .The behavior of the auxiliary outputs is defined by
the parameter ‘’Compressor activation mode’’ (
1.2.x.28
- (
33
)).
In ''Incremental mode' 'when only the main compressor output is activated, the controller assumes that the compressor works at 33.3% of its capacity.
When actuating auxiliary output 1 it will increase the capacity to 66.6% and when actuating auxiliary output 2 to 100% of the compressor's nominal
capacity. In “unloader mode” when the compressor output is actuated, the controller assumes that the compressor works at 100% of its capacity. When
actuating auxiliary output 1, the activated capacity will be 66.6% and when the second auxiliary output is actuated, the activated capacity will be 33.3%
of the nominal capacity.
In “Selective mode” when only the main compressor output is actuated, the controller assumes that the compressor works at 100% of its capacity. When
actuating auxiliary output 2, there is 66.6% and when auxiliary output 2 is switched off and on, auxiliary output 1 has 33.3% of the compressor's nominal
capacity.
20
