13
After the rotation speed attained at 50~70rps, it is necessary to keep the speed for one minute. Because it is
to prevent the oil lack to sliding portion by oil level down at compressor-start. To check oil return, perform a
test using a sight glass compressor supplied by us. Similar action also applies to restart operations after
defrost cycle.
3.5 Stopping of compressor
When compressor needs to stop in high running speed, it is recommended to decrease the speed before
compressor shutting off, in order to low down the impact to inverter, and avoid too much oil left in the system.
In case of emergency stop, direct cut off of power supply can be done.
Figure 3-3 Stopping
3.6 Rate of revolution speed change
The rate of operation speed change of the inverter compressor can affect the reliability of compressor.
The rate of revolution speed change shall be within 1~3rps. This is to prevent the damage of sliding portion
of bearing parts by rapid change of rotation.
The rate of speed change shall be determined after confirmation of compressor oil level, liquid back, and
reliability. If there is a specific description in the compressor specification, follow the contents.
3.7 Defrost operation
Inverter compressors shall operate at low speed right before the start of defrost cycle and right before the
end of defrost cycle. This will enable the oil to be retained in the compressor. To check oil return, perform a
test using a sight glass compressor supplied by us.
3.8 Cautions of transition phase to lower speed operation
For inverter compressors, to prevent plunge of refrigeration capacity due to separation of fixed scroll and orbit
scroll, pay attention to sharp drop of pressure difference and liquid back, when transferring to low speed
operation of below1500 min
-1
.
If there is a specific description in the compressor specification, follow the contents.
3.9 Caution for continuous low speed/high speed operation
When the inverter scroll compressor be operated at low speed or high speed conditions as described below,
it is necessary to adjust the speed of inverter compressor to 50-60rps for more than 3minutes operation, then
back to normal speed control logic according to cooling load.
90rps
Time
f(rps)
