113
JOHNSON CONTROLS
FORM NO.: 6U6K-B01E-NB-EN
pressures detected are measured by gauge pressure. The ratio
must be kept in a certain range to make sure the compressor is
running within its envelope.
Compress ratio = (Pd+100) / (Ps+100);
Where:
Pd: Discharge gauge pressure, kPa;
Ps: Suction gauge pressure, kPa.
The ratio limitations are listed in Table 35 when loading is
prevented.
TABLE 35 -
COMPRESS RATIO LOADING PREVENT-
ION LIMITATIONS
TABLE 37 -
COOLING DT LIMITATIONS
INVERTER FREQUENCY CONTROL
The frequency of the inverter compressor start-up, operation
and stop when rising speed and descending speed should be in
accordance with the figure below.
The compressor must be maintained on the stable platform (40
to 75 RPS, 50 as default) for at least 1 minute before load or
unload.
The frequency change rate of rising speed and descending
speed is 1 RPS (revolution per second).
Cooling
Heating
Fixed Speed SYS.
6.2
6.6
Inverter SYS.
7.8
7.8
The ratio limitations are listed in Table 36 when unload is
mandatory.
TABLE 36 -
COMPRESS RATIO UNLOAD LIMITATIONS
DISCHARGE TEMPERATURE CONTROLS
Discharge temperature controls are available on inverter
system. External temperature sensors are fitted in the discharge
lines of each compressor for continuous detection. The inverter
compressor will be prevented to load or forced to unload if the
temperature is too high. The limitations in cooling mode are
listed in Table 37.
Cooling
Heating
Fixed Speed SYS.
8.1
8.1
Inverter SYS.
8.1
8.1
DT (°C)
Duration (s)
Inverter Compressor
DT<108
°C
/
Normal operation
108
≤
DT
≤
111
/
Load prevented
111<DT
≤
115
/
Unload 1Hz/5s
DT>115
<30
Unload 2Hz/5s
DT>115
≥
30
Reduce to minimum frequency (40Hz)
RPS
5
Target
Target
1RPS
1RPS
1RPS
(40-75)
1 minute or more
Time
RPS
FIGURE 42 –
INVERTER LOADING PROCESS
SECTION 9 – UNIT OPERATION
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
