Parker CDAS HL 050 Series, User Manual

Page: 23 / 398

19
3.5.5 Purge Economy
Purge economy is designed to stop the dryer regeneration cycle when the compressor goes off load, saving energy.
Purge economy can only operate if the dryer is installed directly after the compressor AND before an air receiver. Under no circumstances should
purge economy be connected if there is an upstream, wet air receiver as this will saturate the desiccant bed, lose dewpoint and invalidate the
dryer warranty.
It uses a 24V DC signal from the compressor to stop the dryer regeneration cycle and close the exhaust valve. This prevents unnecessary use of
purge air, saving energy & money. Once the system pressure drops due to actual air demand, the compressor re-starts and the normal drying
cycle will be resumed.
When a 24VDC signal is present at the purge economy digital input, the dryer will continue running to the end of its half cycle and then freeze the
dryer cycle at that point. The active inlet valve will remain energised. The fault relay(s) and spare output(s) will remain energised and the purge
economy visual element displayed.
When the 24VDC signal is removed, the dryer will continue cycling.
3.5.6 Dewpoint Selection / Alarm Values
Dewpoint Selection
During set-up, the control board dipswitches must be set to the dewpoint for which the dryer was sized. This will also configure the ECO Set Point
and Dewpoint Alarm Set Point.
Dewpoint ECO Set Point Dewpoint Alarm Set Point
-20°C (-4°F) -20°C (-4°F) -5°C (-23°F)
-40°C (-40°F) -40°C (-40°F) -20°C (-4°F)
-70°C (-100°F) -70°C (-100°F) -56°C (-68°F)
Purge Economy
Connections