Danfoss AK-PC 560 User Manual page 3

Function
Capacity regulation
The cut-in capacity is controlled by signals from the connected
pressure transmitter and the set reference.
Outside the reference a neutral zone is set .
The digital scroll compressor controls the capacity in the neutral
zone in order to maintain the pressure. When the digital scroll
compressor can no longer maintain the pressure within the neu-
tral zone, the controller will cut out or cut in the next compressor
in the row.
When extra capacity is either cut out or cut in, the capacity from
the digital scroll will be modified accordingly to maintain the pres-
sure within the neutral zone.
- When the pressure is higher than the "reference + half neutral
zone", cut-in of the next compressor (arrow up) is permitted.
- When the pressure is lower than the "reference - half neutral
zone", cut-out of a compressor (arrow down) is permitted.
- When the pressure is within the neutral zone, the process contin-
ues with the compressors already cut in, and the digital scroll will
modulate the capacity.
Cutin of steps can be defined for either sequential or cyclic.
Sequential (first in - last out)
The relays are here cut in in sequence – first relay number 1, then
3, etc.
Cutout takes place in the opposite sequence, i.e. the last cut-in
relay will be cut out first.
Cyclic (first in - first out)
The relays are coupled here so that the operating time of the
individual relays will become equalised.
At each cutin the regulation scans the individual relays' timer,
cutting in the relay with least time on it.
At each cutout a similar thing happens. Here the relay is cut out
that has most hours on the timer.
AK-PC 560
Rx = random relay (3 - 8)
h = number of hours
Manual RS8GE202 © Danfoss 01-2016 3